Water Quality of Bear Creek Basin, Jackson County, Oregon · 2010-11-26 · Water Quality of Bear Creek Basin, Jackson County, Oregon By Loren A. Wittenberg and Stuart W. McKenzie

Water Quality of Bear Creek Basin, Jackson County, Oregon

By Loren A. Wittenberg and Stuart W. McKenzie

U.S. GEOLOGICAL SURVEYWater-Resources Investigations Open-File Report 80-158

Prepared in cooperation with theRogue Valley Council of Governments and theOregon Department of Environmental Quality

1980

UNITED STATES DEPARTMENT OF THE INTERIOR

CECIL D. ANDRUS, Secretary

GEOLOGICAL SURVEY

H. William Menard, Director

For additional information write to:

U.S. GEOLOGICAL SURVEY P. 0. Box 3202 Portland, Oregon 97208

ContentsPage

Conversion factors --------------------------------------------------------Abstract------------------------------------------------------------------ 1

PART I - EXECUTIVE SUMMARY

Introduction-------------------------------------------------------------- 5Identified water uses in Bear Creek basin---------------------------- 6

Water-quality standards----------------------------------------- 6Reference levels------------------------------------------------ 9

Water-quality problems in Bear Creek basin--------------------------- 10Irrigation-water assessment----------------------------------------------- n

On-farm use---------------------------------------------------------- 11Pastures-------------------------------------------------------- 12Cultivated orchards --------------------------------------------- 14Row crops------------------------------------------------------- 14

Irrigation-cana1-and-stream system------------- -------------------- 14Talent Irrigation District-------------------------------------- 14Medford Irrigation District------------------------------------- 16Rogue River Valley Irrigation District-------------------------- 16Whetstone Creek------------------------------------------------- 17

Bear Creek and tributary assessment--------------------------------------- 17Conclusions--------------------------------------------------------------- 31

PART II - TECHNICAL DISCUSSION

Background---------------------------------------------------------------- 37Basin description---------------------------------------------------- 37Hydrologic system---------------------------------------------------- 37Past investigations-------------------------------------------------- 39

Irrigation-water assessment----------------------------------------------- 40On-farm use---------------------------------------------------------- 40

Pa sture s-------------------------------------------------------- 40Cultivated orchards--------------------------------------------- 43Row crops------------------------------------------------------- 47

Irrigation-canal-and-stream system- ------------------------------- 47Talent Irrigation District-------------------------------------- 50Medford Irrigation District------------------------------------- 51Rogue River Valley Irrigation District-------------------------- 54Whetstone Creek------------------------------------------------- 56Comparison of waters at points of irrigation diversion and

Bear Creek at Kirtland Road----------------------------------- 56Bear Creek and tributaries------------------------------------------------ 58

Emigrant subarea--- ------------------------------------------------ 59Ashland subarea------------------------------------------------------ 62Talent subarea------------------------------------------------------- 65Phoenix subarea------------------------------------------------------ 68Medford subarea------------------------------------------------------ 72Central Point subarea------------------------------------------------ 75

iii

Page

Bear Creek and tributaries--ContinuedDiel sites----------------------------- ---------------------------- 79

DissoIved oxygen------------------------------------------------ 80pH -- 85Specific conductance and alkalinity----------------------------- 90Ammonia and nitrite-------------- ----------------------------- 90Periphyton------------------------------------------------------ 93Benthic invertebrates------------------------------------------- 95

References cited---------------------------------------------------------- 97

PART III - WATER-QUALITY CHARACTERISTICS

Water-quality characteristics and cause-effect relationships-------------- 105Discharge------------------------------------------------------------ 105Temperature---------------------------- ---------------------------- 105Suspended sediment--------------------------------------------------- 107Turbidity------------------------------------------ --------------- 108Specific conductance and dissolved solids---------------- ---------- 108Dissolved oxygen----------------------------------------------------- 109pH- - 110Nitrogen------------------------------------------------------------- 111Phosphorus------------------- -------------------------------------- H2Indicator bacteria---------------------------------- --------------- 112

Total coliform bacteria----------------------------------------- 112Fecal coliform bacteria----------------------------------------- 113Fecal streptococci bacteria------------------------------------- 113Use of indicator bacteria data in irrigation practices---------- 114

Glossary of selected terms------------------------------------------------ 115

IV

Illustrations[Plate is in pocket]

Plate 1. Map showing water-quality sampling sites in Bear Creek basin, Jackson County, Oregon

Page

Figure 1. Map showing source, conveyance, and distribution ofirrigation water in Bear Creek basin------------------------- 7

2. Map showing the six subareas in Bear Creek basin--------------- 193. Graph showing percentage of measurements that did not

meet the State standard for dissolved oxygen in six subareas of Bear Creek basin--------------------------------- 21

4. Graph showing percentage of measurements exceeding the maximum State standard for pH in six subareas of Bear Creek basin-------------------------------------------------- 22

5. Graph showing percentage of fecal coliform concentrations exceeding State standards in six subareas of Bear Creek basin-------------------------------------------------- 23

6. Graph showing percentage of fecal streptococci measure ments greater than 1,000 bacteria per 100 mL in six subareas of Bear Creek basin--------------------------------- 24

7. Graph showing variation in turbidity values in sixsubareas of Bear Creek basin--------------------------------- 25

8. Graph showing variation in suspended-sediment con centrations in six subareas of Bear Creek basin-------------- 27

9. Graph showing variation in nitrate concentrations insix subareas of Bear Creek basin----------------------------- 28

10. Graph showing variation in Kjeldahl nitrogen con centrations in six subareas of Bear Creek basin-------------- 29

11. Graph showing variation in orthophosphate concen trations in six subareas of Bear Creek basin----------------- 30

12. Map showing location of study area in Rogue Riverbasin -- ------ -- ------- .._._...... 33

13. Graph showing number of outflow-inflow ratios (for indi vidual farms) showing concentrators, diluters, sources, and sinks for fecal coliform, suspended sediment, and dissolved nitrate in pastures and orchards------------------- 46

14. Map showing Talent Irrigation District------------------------- 5015. Map showing Medford Irrigation District------------------------ 5216. Graph showing suspended-sediment concentrations

at selected sites in Phoenix Canal during 1976 irrigation season-------------------------------------------- 53

17. Graph showing nitrate concentrations at selected sites in Phoenix Canal during 1976 irrigation season------------------------ ----------------------------- 54

18. Map showing Rogue River Valley Irrigation District------------- 5519. Graphs showing diel fluctuations of water-quality

parameters and solar radiation for Bear Creek at Barnett Road at Medford (site 104), August 16-17, 1977 81

v

\Page

Figure 20. Graphs showing dissolved oxygen and relateddata at diel sites in Bear Creek basin---------------------- 84

21. Graph showing comparison of minimum dissolved oxygen with ultimate biochemical oxygen demand in Bear Creek basin---------------------------------- 85

22. Graph showing pH and related data at diel sitesin Bear Creek basin----------------------------------------- 87

23. Graph showing comparison of diel pH fluctuations with diel dissolved-oxygen fluctuations in Bear Creek basin-------------------------------------------- 88

24. Graph showing comparison of diel pH fluctuationswith diel water-temperature fluctuations-------------------- 89

25. Graph showing specific conductance, alkalinity, pH, and discharge data at diel sites in Bear Creek basin-------------------------------------------- 91

26. Graph showing mean monthly discharges for 1959-77water years------------------------------------------------- 106

VI

TablesPage

Table 1. Median ratios of selected water-quality char acteristics of water samples from pastures and orchards------------------------------------------------ 12

2. Median values of selected water-quality char acteristics of inflow and outflow water samples----------------------------------------------------- 13

3. Number of times water-quality standards or reference levels were not met in irrigation-delivery canals and streams------------------------------------------ 15

4. Sources of stored water for irrigation districts-------------- 395. Ratio of outflow to inflow samples for selected

water-quality characteristics from pastures----------------- 416. Inflow and outflow values for selected water-

quality characteristics from pastures----------------------- 427. Ratio of outflow to inflow samples for selected

water-quality characteristics from cultivated orchards---------------------------------------------------- 44

8. Inflow and outflow values for selected water- quality characteristics from cultivated orchards---------------------------------------------------- 45

9. Ratio of outflow to inflow samples for selectedwater-quality characteristics from row crops---------------- 48

10. Inflow and outflow values for selected water- quality characteristics from row crops---------------------- 48

11. Median water-quality characteristics inirrigation waters of canals and streams--------------------- 49

12. Quality characteristics of water diverted for irrigation and water leaving the Bear Creek basin, May-September 1976----------------------------------- 57

13-18. Water-quality median values for subareas of Bear Creek basin:

13. Emigrant subarea------------------------------------- 6014. Ashland subarea-------------------------------------- 6315. Talent subarea--------------------------------------- 6716. Phoenix subarea-------------------------------------- 7017. Medford subarea-------------------------------------- 7318. Central Point subarea-------------------------------- 77

19. List of diel sites ----------------------------------------- 7920. Summary of diel data relating to dissolved oxygen------------- 8221. Summary of data collected at diel sites

relating to PH---------------------------------------------- 8622. Concentrations of ammonia and nitrite nitrogen

in Bear Creek during 1977 diel studies---------------------- 9223. Summary of 1977 periphyton data from Bear Creek--------------- 9424. Summary of 1977 benthic invertebrate data from

Bear Creek-------------------------------------------------- 96

vii

Conversion factors for inch-pound system and International System Units (SI)

[For use of those readers who may prefer to use metric units rather than inch-pound units, the conversion factors for the terms used in this report are listed below:]

Multiply inch-pound unit By To obtain metric unit

Length

inch (in.) mile (mi)

25.401.609

millimeter (mm) kilometer (km)

Area

square mile (mi2 )acreacre-foot (acre-ft)

2.5904,0471,233

square kilometer (km ) square meter (m2 ) cubic meter (m 3 )

Volume per unit time (includes flow)

cubic foot per second (ft3 /s) gallon per minute (gal/min) million gallons per day (Mgal/d)

0.028320.063090.04381

cubic meters per second (m3 /s)liters per second (L/s)cubic meter per second (m3 /s)

Mass

ton (short, 2,000 Ib) per day (ton/d) 0.9072 tonne per day (t/d)

Temperature

degree Fahrenheit (°F) 5/9 after subtracting 32 degree Celsius (°C)

Energy per unit area per time

British thermal unit per square foot per minute (Btu/ft 2 /min) 0.2712

Calorie per square cm per min (calorie/cm2 /min)

Vlll

Water Quality of Bear Creek Basin, Jackson County, Oregon

By Loren A. Wittenberg and Stuart W. McKenzie

ABSTRACT

Samples of water in the Bear Creek basin were collected from irrigation and return-flow channels on farms and from canals and streams for analysis of physical, chemical, and biological characteristics. These data, along with measured flows, were used to identify major surface-water-quality problems in the basin and, where possible, their causes or sources. This report includes three parts--executive summary, technical discussion, and explanation of water-quality characteristics.

Irrigation and return-flow data collected on farms show that pastures are sources of fecal coliform and fecal streptococci bacteria and sinks for sus pended sediment and nitrite-plus-nitrate nitrogen. Orchards act as concen trators of these constituents. Water in the canals shows a general degra dation of quality in a downstream direction and in a down-basin direction from one canal system to another.

Bear Creek and its tributaries have exhibited dissolved oxygen and pH values that do not meet Oregon Department of Environmental Quality water- quality standards. From the Talent subarea to the Central Point subarea, 40 to 50 percent of the fecal coliform and fecal streptococci concentrations were higher than 1,000 colonies per 100 milliliters during the irrigation season. Also, during the irrigation season, suspended sediment averaged 35 milligrams per liter and turbidity values averaged 15 Jackson turbidity units; both these averages were about double those for the nonirrigation season in lower Bear Creek basin. Nitrite-plus-nitrate concentrations in streams were significantly greater downstream from a sewage-treatment plant and from points of ground- water seepage. A significant source of Kjeldahl nitrogen and orthophosphate in Bear Creek is sewage-treatment-plant effluent.

The marsh on Whetstone Creek reduces the bacteria, suspended sediment, turbidity, and nitrite-plus-nitrate concentrations that are contributed by irrigation-return flows.

PAGE 5 NEXT

INTRODUCTION

The U.S. Geological Survey has undertaken the identification of major surface-water-quality problems in Bear Creek basin and their causes or sources The objective of this study is to provide information to evaluate methods for minimizing problems within the basin. To meet this objective, the Geological Survey began a data-collection program in 1976 that included the following elements:

1. Measurement of the quality and quantity of water in the irrigation- canal -and -stream system.

2. Measurement of the quality and quantity of water delivered to and leaving selected irrigated farm plots.

3. Measurement of the quality and quantity of water in selected streams in Bear Creek basin.

4. Intensive water-quality measurements in the main stem of Bear Creek, including physical, chemical, and biological characteristics (diel studies).

5. Collection of data on precipitation, quality and quantity of storm- water runoff, and combined sewer overflow in four subbasins within Bear Creek basin.

Data collection for the first element was completed in 1976, and for the second, third, and fourth elements in 1977. These data were reported by McKenzie and Wittenberg (1977) and Wittenberg and McKenzie (1978). Data col lection for the fifth element was completed in 1978 (Wittenberg, 1978).

This report presents an interpretation of data collected in the first four elements of the study. Because of funding restrictions, interpretation of the data collected in the fifth element of the study is not planned. The report is divided into three parts part I, executive summary; part II, tech nical discussion; and part III, explanation of water-quality characteristics.

Irrigation is a requirement for agriculture in the Bear Creek basin. Without the use of stored water in the basin and importation of water from outside the basin, low-flow or no-flow conditions would occur in most creeks during late summer and early fall. The irrigation water is distributed by the Talent, Medford, and Rogue River Valley Irrigation Districts. Water is diverted from streams within Bear Creek basin and from the Klamath River basin to the east and the Little Applegate River basin to the southwest through a series of canals and natural streams receiving irrigation-supply water and irrigation-return flow (see fig. 1).

\Identified Water Uses in Bear Creek Basin

The Oregon Department of Environmental Quality (1977) has identified the following beneficial uses of water from Bear Creek:

1. Public domestic water supply (designation for this use is presently under study)

2. Industrial water supply

3. Irrigation (including water for frost protection of orchards)

4. Livestock watering

5. Anadromous fish passage

6. Salmonid fish rearing

7. Salmonid fish spawning

8. Resident fish and aquatic life

9. Wildlife and hunting

10. Fishing

11. Boating

12. Water-contact recreation

The Department of Environmental Quality also includes esthetic quality in its list of beneficial uses.

To provide a quality of water adequate to meet the above identified uses, the Oregon Department of Environmental Quality (DEQ) has set water-quality standards as shown in the following section.

Water-Quality Standards

State water-quality standards have been set by DEQ (1977) for temperature, turbidity, dissolved oxygen, pH, and "organisms of the coliform group where associated with fecal sources" for which the fecal coliform test is used. The temperature and turbLdity standards apply only to point sources. Those State standards that are used in this report as listed as follows:

§ oo

Irri

gBtio

n d

istr

ibu

tio

n

syst

em --

Bea

r C

reek

dra

inag

e ba

sin

Bas

e fr

om

the

S

tate

Wat

er

Res

ourc

es

Boa

rd,

Rop

ue

Dra

inag

e B

asin

, 19

70

Figu

re

1.-S

ourc

e, c

onve

yanc

e,

and

dist

ribu

tion

of i

rrig

atio

n w

ater

in

Be

ar

Cre

ek

basi

n.

7

Characteristic

Dissolved oxygen (percent saturation)

pH (units)

Fecal coliform(colonies/100 mL)

State standard

Not less than 90

Within range of 6.5-8.5

Not greater than 1,000 (except during storm conditions)

As used in this report, a State standard is not met when a measured value falls outside the criteria range listed above. DEQ (1977) water-quality standards include the statement "Where the natural quality parameters of water * * * are outside the numerical limits of * * * water quality standards, the natural water quality shall be the standard." Although a value is outside the criteria range listed above, it may not be outside the range of "natural water quality" that is undefined by DEQ at this time. This often occurred with dissolved oxygen and pH data collected over 24 hours (diel data).

Reference Levels

The authors have selected reference levels for certain water-quality characteristics to help identify causes of wat;er-quality problems, sources of constituents, and to aid in interpreting data in this report. These refer ence levels were arbitrarily selected for use as comparative values and often are equal to natural or background water-quality values. These levels are not standards and should not be used as such by readers of this report. Their use in another area of the State or country would be of questionable value. The reference levels are as follows:

Characteristic

Suspended sediment (mg/L)

Turbidity (Jtu)

Dissolved un-ionized ammonia as N (mg/L)

Dissolved nitrite as N (mg/L)

Dissolved nitrite-plus-nitrate as N (mg/L)

Dissolved orthophosphate as P (mg/L)

Fecal streptococci (colonies/100 mL)

Reference level (maximum)

20

15

.02

.06

1.0

.06

1,000

The following is a brief discussion of how each of the reference levels was chosen.

\Suspended sediment - 20 mg/L.--This concentration is approximately equal to

the discharge-weighted average of all irrigation water at or near points of diversion listed in table 12 (part II). The reference level gener ally is exceeded in streams during periods of overland runoff resulting from storms.

Turbidity - 15 Jtu (Jackson turbidity unit).--This value was arbitrarily chosen and is higher than that recommended by the National Technical Advisory Committee (1968). The reference level in streams generally is exceeded during periods of overland runoff resulting from storms.

Dissolved un-ionized ammonia as N - 0.02 mg/L.--This concentration was chosen to agree with the recommended criterion of the U.S. Environmental Pro tection Agency (1976). The value is one-tenth of the lowest values shown to be toxic to some species of freshwater aquatic life.

Dissolved nitrite as N - 0.06 mg/L.--At or below this concentration, nitrite should not harm salmonid fish (U.S. Environmental Protection Agency, 1976). This high concentration is unlikely to occur in natural surface water.

Dissolved nitrite-plus-nitrate as N (hereinafter referred to as nitrate) - 1.0 mg/L.--This concentration is arbitrarily chosen. Nitrate at this concentration is known to cause algal blooms in lakes. As discussed by Rickert and others (1977b), nuisance algal growths in rivers are believed to be controlled by:

1. Low water temperatures2. High summertime turbidities3. Scarcity of certain trace nutrients4. Short detention time in the stream system

Dissolved orthophosphate as P - 0.06 mg/L.--Orthophosphate is that portion of the total phosphate that is readily available to plants. When nitrate has a concentration of 1.0 mg/L, the reference level of 0.06 mg/L of orthophosphate is near the desirable ratio (16N:1P) of nutrients to support plant growth (Stumm and Morgan, 1970; Kramer and others, 1972).

Fecal streptococci - 1,000 colonies/100 mL.--A concentration equal to theState standard set for fecal coliform has been selected as the reference level because the two indicator bacteria groups may have a similar source--fecal material.

Water-Quality Problems in Bear Creek Basin

A water-quality problem exists when a characteristic of water (a con stituent or property of water) decreases its suitability or prevents its use for some intended purpose. Three examples of water-quality problems are bacteria in drinking water, high turbidity in a municipal supply, and a large amount of oxygen-demanding material in a stream.

10

To correct water-quality problems, the water can be treated to remove its use-limiting characteristics, as is done at water-treatment and sewage- treatment plants; or the undesirable characteristics can be prevented from entering the water. The methods for correcting a problem can best be deter mined by understanding (1) the use of water and, thus, the quality of water needed; (2) how water quality is measured; (3) what water-quality data mean; and (4) the causes or sources of water-quality problems.

La Riviere, Quan, Westgarth, and Culver (1977) identified several questions that needed to be answered in order to identify and minimize water- quality problems in Bear Creek basin. These questions, along with answers, are shown on pages 31 to 33.

IRRIGATION-WATER ASSESSMENT

During the 1976 irrigation season, water from canals and selected streams was sampled by the Geological Survey to identify water-quality problems. In an attempt to isolate the sources of the problems, a followup study was made by sampling irrigation inflow and outflow water at farm plots during the 1977 irrigation season.

The irrigation method and crop type generally will determine whether a farm plot acts as a concentrator or diluter of constituents in water or as a source or sink. Explanations of these terms are shown below.

CONCENTRATION (weight/volume)

Outflow greater than inflow = Concentrator Outflow less than inflow = Diluter

LOAD (weight/time)

Outflow greater than inflow = Source Outflow less than inflow = Sink

On-Farm Use

In an effort to avoid the large expense of continuous monitoring of characteristics in irrigation water entering and leaving farm plots, the study used a "random-sample" approach. This means that some time after the water was turned on, and some time after water commenced running off the farm plot, inflow and outflow samples were taken. Generally these samples were taken at the same time. Inflow and outflow concentrations and outflow dis charge can vary as much as 100 percent of the mean value during a period of irrigation (L. A. King, U.S. Department of Agriculture, oral commun., June 1977). When considered together, however, all irrigation plots containing the same type of crop are assumed to constitute a random sampling, and pro vide estimates of the average and range of water-quality changes produced by farm plots containing that crop.

11

Samples of inflow and outflow water were taken from pastures, orchards, and row crops. During the 1977 growing season, most of the orchards were under cultivation to limit the growth of grass and weeds. Tables 1 and 2 show the median ratios (outflow/inflow) and mean values, respectively, of selected water-quality characteristics for outflow and inflow water samples for pastures and orchards.

Table 1.--Median ratios (outflow/inflow) of selected water-quality characteristics of water samples from pastures and orchards

Characteristic

Fecal coliform

Fecal streptococci

Suspended sediment

Dissolved nitrate as N

Total Kjeldahl nitrogen as N

Dissolved orthophosphate as P

PastureConcen tration ratio

4.0

7.5

.37

.27

2.4

1.1

Load ratio

1.6

3.4

.07

.04

.59

.30

OrchardConcen tration ratio

2.6

2.0

2.7

5.9

--

1.2

Load ratio

0.48

.82

.31

1.1

--

.49

Pastures

As indicated in table 1, pastures are sources of bacteria. In all but two pastures sampled, the outflow water contained fecal coliform bacteria con centrations in excess of the State standard. Fecal streptococci bacteria con centrations for all outflows from pastures exceeded reference levels. Bacteria in water flowing from pastures are probably a combination of those already in the water and bacteria picked up in the pastures from fecal matter of birds, livestock, and other warmblooded animals.

Pastures tend to filter suspended sediment from the water, and thus they are sinks for sediment and Kjeldahl nitrogen. Pastures also act as concen trators of Kjeldahl nitrogen. Both nitrate concentrations and loads decreased, probably due to rapid uptake by the pasture grasses. The dissolved oxygen was below 90 percent saturation in all but one sampling of water flowing from pastures.

12

Tabl

e 2.--Median va

lues

of

selected wat

er-q

uali

ty characteristic

s of

in

flow

and ou

tflo

wwater

samp

les

[App

roxi

mate

number of analyses of

water for

each cr

op type wer

e pa

stur

e, 13

; orchards,

15;

beet

se

ed,

2; grass

seed,

1]

Characteristic

Turb

idit

y (J

tu)

Spec

ific

co

nduc

tanc

e (u

mhos

/cm

at 25

°C)

pH (u

nits

)

Temp

erat

ure

(°C)

Dissolved

oxygen

(percent saturation)

Past

ure

Infl

ow 25 180

7.9 16 96

Outflow

5

175

7.5 17 81

Orchards

Infl

ow 15 220

7.9 17 99

Outf

low

25 230

7.2 19 92

Beet

se

edIn

flow 9

325

7.7 17 77

Outflow

12

500

7.2 17 29

Grass

seed

Infl

ow 9

305

7.6 15 91

Outflow 5

350

7.4 15 76

Cultivated Orchards

Orchards act as sinks for indicator bacteria; they also act as concen trators and contribute to higher concentrations of bacteria in return-flow streams or lower canals. The greater concentration of bacteria in the outflow water (table 1) may be attributed to the following: (1) concentrating of bacteria already in the water into a smaller volume, and (2) loss of bacteria from the inflow water and a subsequent gain of other bacteria in the orchard from droppings of birds and other warmblooded animals.

Ratios in table 1 indicate that orchards act as sinks and concentrators for suspended sediment. Orchards are also sources of turbidity in streams and lower canals receiving irrigation-return flow. Nitrate-load ratios show no loss or gain for orchard farm plots. The sixfold increase in concentration, however, identifies orchards as concentrators of nitrate.

Median temperature values of water sampled from pastures and orchards show small increases from inflow to outflow samples (see table 2).

Row Crops

Insufficient samples were collected from row crops for a detailed inter pretation, but some conclusions can be drawn. Harvested beet-seed fields were found to be sources of indicator bacteria and orthophosphate. Dissolved- oxygen mean concentration was 29 percent of saturation in outflow water from the beet-seed fields.

The partly burned grass-seed field was a sink for indicator bacteria, suspended sediment, nitrate, and a source of orthophosphate. Dissolved oxygen was below 90 percent saturation.

Irrigation-Canal-and-Stream System

The irrigation-canal-and-stream investigation included water-quality sampling near points of diversion, near the ends of the canals, and from selected return-flow streams. This sampling was done between March and October 1976. A generalized downstream degradation of water quality within each canal system and in a down-basin direction from one canal system to another was observed. The repeated reuse of water is a significant factor in the degraded quality.

A summary, by irrigation district, of water quality in the canals and streams is presented in table 3.

Talent Irrigation District

The Talent Irrigation District (TID) includes the Ashland, East, West, Talent, and Lower East Laterals (see figs. 1, 14). Meyer and Payne Creeks are streams receiving irrigation-return flow, also in the TID area.

14

Tabl

e 3.-

Num

ber

of

times

wat

er-q

ualit

y st

anda

rds

or r

efer

ence

lev

els

wer

e no

t m

et i

n ir

riga

tion-

deliv

ery

cana

ls a

nd s

trea

ms

in B

ear

Cre

ek b

asin

[I

n "I

ndic

ator

bac

teri

a" c

olum

n, F

c=fe

cal

colif

orm

and

FS=

feca

l st

rept

ococ

ci.

In c

olum

ns w

here

a f

ract

ion

is sh

own,

the

den

omin

ator

ind

icat

es a

num

ber

of m

easu

rem

ents

tha

t di

ffer

s fr

om t

he n

umbe

r lis

ted

unde

r "N

umbe

r of

sam

ples

col

lect

ed."

Fo

r ex

ampl

e, %

mea

ns o

ne o

ccur

renc

e in

fou

r sa

mpl

es]

Irri

gatio

ndi

stri

ct

Tal

ent

Med

ford

Rog

ue R

iver

' V

alle

y

Can

al a

nd d

rain

age

Ash

land

Lat

eral

Eas

t L

ater

alW

est

Lat

eral

Mey

er C

reek

Payn

e C

reek

Tal

ent

Lat

eral

Low

er E

ast

Lat

eral

Med

ford

Irr

igat

ion

Dis

tric

tC

anal

Phoe

nix

Can

al

Hop

kins

Can

al (

east

sid

e)L

one

Pine

Cre

ekB

ear

Cre

ek C

anal

and

Hop

kins

Can

al (

wes

t si

de)

Whe

tsto

ne C

reek

Num

ber

ofsa

mpl

es

10 10 5 7 6 10 3 11 27 15 6 10 7

Indi

cato

rba

cter

iaFc 0 0

0/4

3/6 5 3 2 4

9/26 5

1/5 3 0

Fs 0/6

0/6

0/4

2/5

4/4

4/6

2/2

3/7

8/17

3/8

1/5

5/6

1/5

Susp

ende

dse

dim

ent

1 5 5 2 5 4 1 1120

/2$ 10 0 7 1

Tur

bidi

ty

0 6 5 0 5 3 0 6 14 6 0 2 0

Dis

solv

edox

ygen

0 0 0 0 1 0 0 0 1 1 0 3 1

PH 1/6

1/8

0/4 0 0

0/8 0

2/10

3/23

2/14 0

2/8

2/6

Nitr

ate

0/8

0/8

0/4

0/6 0

0/8

0/2

0/9

1/22

0/12

0/5

1/8

0/6

Ort

ho-

phos

ph

ate

0/8 1

0/4

0/6 0

0/8

1/2

2/9

20/2

2

7/12

5/5

7/8

2/6

Table 3 shows that fecal coliform concentrations exceeded the State standard of 1,000 colonies per 100 mL at four of seven creeks and laterals sampled. High concentrations of fecal streptococci were also present at these same sites. These high concentrations are probably caused by irrigation- return flow, animals, and domestic sewage. The suspended-sediment concen trations and turbidity values are greater than the reference levels and may be caused by cattle damaging canal banks, channel scour, and irrigation-return flow. Emigrant Reservoir is one source of the turbidity in the canals. Values of the pH exceeding the State standard for pH in the Ashland and East Laterals are associated with high dissolved oxygen and high temperature, sug gesting the cause to be biological productivity. Ground-water seepage may be the source of increased concentrations of nitrate. The source of orthophosphate in the Lower East Lateral is not known. Because the water in Lower East and Talent Laterals contains irrigation-return flow and ground water, it is more degraded than water in Ashland and East Laterals, which contains little or no irrigation-return flow.

Medford Irrigation District

The Medford Irrigation District (MID) includes the MID and Phoenix Canals (see figs. 1, 15). Sources of fecal bacteria, suspended sediment, and turb idity in the MID Canal include tail water from the East Lateral in addition to to all previously identified sources.

The water in the Phoenix Canal, diverted from Bear Creek at Talent, is of poorer quality than that in the other canals discussed thus far. Sewage- treatment-plant (STP) effluent, which enters Bear Creek via Ashland Creek, is a major source of nutrient concentration in the canal; degradation, however, is also due in part to repeated reuse of the water for irrigation. Suspended sediment and nutrients in the Phoenix Canal show a seasonal trend, and other canal systems probably follow a similar trend.

Rogue River Valley Irrigation District

The Rogue River Valley Irrigation District (RRVID) includes the Hopkins and Bear Creek Canals (see figs. 1, 18). The quality of water in the canal near its diversion at Bradshaw Drop is similar to that of the tail water of Ashland Lateral. Water in the lower part of the Hopkins Canal (east side of Bear Creek basin) includes water diverted from Lone Pine Creek. The quality of water in the canal below its confluence with Lone Pine Creek is better than the quality above the confluence. This is an example of how augmentation with high-quality water can improve the water quality of canals and streams. The high-quality creek water is overflow from the Medford Aqueduct (the municipal water supply for the city of Medford) plus some irrigation-return flow.

Table 3 shows that Bear Creek Canal, containing water diverted from Bear Creek at Jackson Street, and Hopkins Canal (west side of Bear Creek basin) have the poorest quality of water of any of the canals. This may be caused by a combination of reuse of water for irrigation, effects of sewage-treatment- plant effluent, and ground-water inflow.

16

Whetstone Creek

Whetstone Creek, which contains ground water and irrigation-return flows, drains an area south and west of White City. The creek flows through a marsh and empties into the Rogue River below the Medford STP. Water sampled from the creek near its mouth had lower concentrations of bacteria, suspended sedi ment, and nitrate, and lower turbidity levels than did other streams contain ing irrigation-return flow (Meyer and Payne Creeks). Filtration by rooted vegetation apparently results in settling of suspended sediment and reduction of turbidity in the creek. State standards for pH were not met in two of six samples. Water of Whetstone Creek is similar in quality to the tail water of the Ashland lateral.

BEAR CREEK AND TRIBUTARY ASSESSMENT

This part of the report summarizes the water-quality data available for Bear Creek and its tributaries. To aid in interpretation, the data are divided as follows:

1. Six data sets representing the six subareas, as shown in figure 2.

2. Two hydrologic regimens:

a. Nonirrigation season and base flow (nonirrigation regimen).-- The nonirrigation regimen includes samples collected (1) during fall, winter, and early spring (to March 31); (2) when no over land flow resulted from storms; and (3) when the streamflows were not high from recent storms.

b. Irrigation season and base flow (irrigation regimen).--The irri gation regimen includes samples collected (1) during the irriga tion season (April through September), and (2) when there was no overland flow resulting from storms.

3. Dissolved-oxygen and pH data collected between 9 a.m. and 4 p.m. (nondiel data) are separated from the diel data collected over a 24-hour period.

Figures 3 through 6 illustrate the percentage of measurements that did not meet State standards in each of the subareas. Figures 7 through 11 are plots of average values for each of the subareas.

Analysis of the water-quality data shows the following:

1. The data for each subarea indicate no apparent long-term trends.

2. Eight percent of the nondiel measurements on Bear Creek and tribu taries and 41 percent of the diel measurements on Bear Creek were lower than the State standard (90 percent of saturation) for dis solved oxygen (DO). The large incidence of oxygen deficiency related to the diel measurements is partly due to the loss of DO at night as the result of respiration of aquatic life. Other causes of

17

low DO concentrations include (a) bacterial oxidation of organic material from point and nonpoint sources, and (b) oxidation of ammo nia from sewage-treatment-plant effluent to nitrite and then nitrate (nitrification). A reduction in biochemical oxygen demand (BOD) and ammonia in the stream would help to prevent the DO from dropping below the State standard.

The percentage of measurements that did not meet State standard for DO in each subarea is shown in figure 3. The Emigrant subarea in cludes no sewage-treatment-plant effluent and little irrigation- return flow. The Ashland and Talent subareas include sewage-treatment- plant effluent and irrigation-return flow. Most of the water con taining the sewage-treatment-plant effluent is diverted out of Bear Creek for irrigation downstream from the Talent subarea. Irrigation- return flow is the main source of water to Bear Creek downstream from the Talent subarea. The DO data in the Talent subarea tributaries met State standards. No significant difference was noted between irrigation and nonirrigation seasons. The large percentage of low DO concentrations measured at the Bear Creek site in the Talent subarea appears to be the result of BOD and ammonia loading from the sewage-treatment-plant effluent.

3. The difference between diel and nondiel measurements is less for pH data (fig. 4) than for dissolved-oxygen data because high pH (exceed ing State standards) occurred during the day, when both diel and non diel data were collected. Water in the three upstream subareas was within State pH standards except for a few pH values observed in Bear Creek where there were few periphyton (microscopic plants and animals attached to submerged material in streams). A high percentage of the pH measurements were outside the State standard in the three down stream subareas, where there were large numbers of periphyton.

4. As shown in figures 5 and 6, bacteria concentrations were highest (a) during the irrigation regimen and (b) in the four downstream subareas of Bear Creek basin. During the irrigation regimen, there was a higher number of fecal streptococci than fecal coliform bacteria. Figure 6 shows that tributaries to Bear Creek generally have higher concentrations of fecal streptococci bacteria than does the main stem.

Indicator bacteria concentrations appear to be associated with the activities of man. For example, higher concentrations are found during the irrigation season, when activity on the land is greatest; and near urbanized areas, where the population density is greatest. Man may be a contributor of indicator bacteria, but the animals associated with man may also be significant contributors.

5. Figure 7 shows that average turbidity is high in the Emigrant subarea. Emigrant Reservoir is a we11-documented source of turbidity (Pugsley, 1972). Because of irrigation-return flow, the lower four subareas also have high turbidities. During the 1977 water year

18

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EXPLANATION

- Diel data

-O- Nondiel data

72 Number of measurements

104

119

176

Emigrant Ashland Talent Phoenix Medford Central Point

SUBAREAS OF BEAR CREEK BASIN ( Direction of flow -)

Figure 3.-Percentage of measurements that did not meet the State standard for dissolved oxygen in six subareas of Bear Creek basin.

21

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10

EXPLANATION

-O Nonirrigation regimen data

Irrigation regimen data

20 Number of samples

65

67

106

Emigrant Ashlandx Talent Phoenix Medford Central Point

SUBAREAS OF BEAR CREEK BASIN (Direction of flow )

Figure 5. Percentage of fecal coliform concentrations exceeding State standards in six subareasof Bear Creek basin.

23

PE

RC

EN

TA

GE

O

F

FE

CA

L S

TR

EP

TO

CO

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EA

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x

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24

20

E 16 Om ccD I-

Z O </>

O 12

Q m OC 8

EXPLANATION

Nonirrigation regimen data

Irrigation regimen data


SUBAREAS OF BEAR CREEK BASIN (Direction of flow -)

Figure 7. Variation in turbidity values in six subareas of Bear Creek basin.

25

(a drought year), the turbidity of the water at several sites de creased significantly, suggesting a direct relation between flow and turbidity.

6. Average suspended-sediment concentrations are highest in the four lower subareas of Bear Creek basin, as shown in figure 8. The irrigation-regimen and nonirrigation-regimen data for suspended sedi ment show the same pattern as those for turbidity and have a common cause (irrigation-return flow). The higher suspended-sediment concen trations in the Talent subarea during the nonirrigation regimen, and possibly during the irrigation regimen also, are probably caused by sand from sluicing of Reeder Reservoir. Data on the amount of sedi ment transported downstream during storms, which is generally the period when most sediment is transported, are not included in figure 8.

7. Figure 9 shows the average concentration of nitrate in various subareas of Bear Creek basin. Nitrate concentrations in the main stem are higher in the Ashland, Talent, and Phoenix subareas than in the Emigrant subarea. This increase is attributed to sewage-treatment- plant effluent. The nonirrigation main-stem nitrate concentrations in the Ashland subarea are low because most of the nitrogen is in the form of ammonia which is not oxidized to nitrate until it moves farther downstream. The irrigation main-stem nitrate concentration in the Phoenix subarea is less than in the subareas just upstream, probably because of (a) the rapid uptake of nitrate by periphyton as ammonia is being oxidized, and (b) dilution by irrigation-return flows. Ground water containing high concentrations of nitrate seeps into the streams, causing high concentrations of nitrate in the Medford subarea nonirrigation tributary samples and also in all the Central Point subarea samples.

8. Figure 10 shows a small increase in mean Kjeldahl nitrogen concen trations in a downstream direction. A significant source of the Kjeldahl nitrogen, composed mainly of ammonia nitrogen, is sewage- treatment-plant effluent.

9. Average orthophosphate concentrations in figure 11 show a similar pattern to Kjeldahl nitrogen, and, again, sewage-treatment-plant effluent is a significant source.

In general, water-quality problems (1) increased during the irrigation regimen and (2) decreased during the low flows of the 1977 water year. Sewage- treatment-plant effluent, ground-water seepage, and irrigation-return flow probably have the most significant effects on water quality in the Bear Creek basin.

26

50

40

30

5z(-*

UJ55 20

aLUQzUJ OL V)

to 10

1 I

EXPLANATION

Nonirrigation regimen data

>- Irrigation regimen data

Emigrant Ashland Talent Phoenix Medford

SUBAREAS OF BEAR CREEK BASIN (Direction of flow

Central Point

Figure 8. Variation in suspended-sediment concentrations in six subareas of Bear Creek basin.

27

1.6

1.4

1.2

2 1.0a.

0.8

0.6

0.4

0.2

EXPLANATION

Nonirrigation- regimen data

Irrigation- regimen data

Tributary sites

Main-stem sites

Emigrant Ashland Talent Phoenix Medford

SUBAREAS OF BEAR CREEK BASIN (Direction of flow

Central Point

Figure 9. Variation in nitrate concentrations in six subareas of Bear Creek basin.

28

1.6

1.4

1.2

1.0

I< 0.6Q

0.8

0.4

0.2

EXPLANATION

-O Nonirrigation regimen data

- Irrigation regimen data Tributary sites Main-stem sites



Figure 10. Variation in Kjeldahl nitrogen concentrations in six subareas of Bear Creek basin.

29

1.2

1.0

0.8

5z«* * 0.6V)

0.4

0.2

EXPLANATION

O Nonirrigation regimen data

" ~ Irrigation regimen data ~ Tributary sites

Main-stem sites



Figure 11 . Variation in orthophosphate concentrations in six subareas of Bear Creek basin.

30

CONCLUSIONS

Water-quality characteristics that could limit or prohibit some of the water uses shown on page 6 are listed below by source:

1. Sewage-treatment-plant effluent.--Ammonia, nitrite, nitrate, and organic nitrogen; total phosphate and orthophosphate; and organic material, as measured by ultimate biochemical oxygen demand (BODU ) and total organic carbon (TOG).

2. Combined-sewer outflow.--Organic material, fecal bacteria, and low DO.

3. Log-pond outflow.--Turbidity, suspended sediment, organic material, and ammonia. The log pond discharged water to Bear Creek during most months of 1977, even during extended periods of very little rainfall (Edison Quan, Oregon Department of Environmental Quality, oral commun., May 15, 1978).

4. Ground-water seepage.--Nitrate.

5. Irrigation-return flow.--Suspended sediment, turbidity, and nitrate from orchards; orthophosphate from pastures; and fecal bacteria from both orchards and pastures.

One area in the Bear Creek basin that shows a high quality of water is Whetstone Creek. The wetland area of Whetstone Creek acts as a "living filter," removing some turbidity, suspended sediment, nitrogen, phosphorus, and bacteria from the water.

Irrigation-related activities that could improve the quality of water are listed below:

1. When irrigation of farm plots is controlled so as not to allow out flow to occur and normal irrigation-return flow is left in streams, water quality of streams will not be directly affected by irrigation- return flow and the quality should improve.

2. Ponds or settling basins can remove some suspended sediment and turbidity-causing materials from irrigation-return flows.

3. The irrigation of pastures removes from water some nitrate, suspended sediment, and other turbidity-causing material. This suggests that grass-lined waste ditches and grass cover in orchards could improve irrigation-return flow quality.

31

The following questions posed by La Riviere, Quan, Westgarth, and Culver (1977, p. 22) are answered by the authors of this report.

1. What are the sources of contamination by fecal bacteria and how can the sources of bacteria be controlled?

Sources of fecal coliform bacteria include combined sewers; irrigation-return flows, especially from pastures; and overland flow. Reduction of combined-sewer and irrigation-return flows could reduce the concentration of fecal coliform bacteria.

2. What benefits can be derived from augmenting Bear Creek flows?

Depending on the source of water and its characteristics, in creased flows in Bear Creek could (a) increase DO concentrations; (b) aid in holding pH below 8.5; (c) decrease turbidity; and (d) decrease concentrations of fecal coliform, fecal streptococci, ammonia, nitrite, nitrate, orthophosphate, and suspended sediment in Bear Creek. Increased flows could also improve the quality of water available from canals for irrigation.

3. What are the man-related sources of suspended sediment in the basin?

Suspended sediment results from overland flow of surface water; point sources, such as combined sewers and industrial outfalls; and the sluicing of Reeder Reservoir. Overland flow includes storm-water runoff as well as irrigation-return flow. Any land-use activity that leaves the soil exposed to erosion contributes to increased concen trations of suspended sediment in the streams. These activities in clude (a) construction of homes, office buildings, and highways; (b) agricultural practices, such as row-crop cultivation, plowing, and disking; and (c) timber harvesting. All these practices either disturb existing vegetative growth or leave the soil devoid of vegetation.

4. What methods can be used to minimize the suspended-sediment problem in the basin?

Suspended-sediment problems can be minimized by controlling or eliminating erosion. This is accomplished by (a) reducing overland flow, (b) minimizing the creation of erosive areas, and (c) inter cepting suspended sediment before it reaches the streams. Some irri gation methods, such as sprinkler and drip, help to reduce overland flow. The use of settling ponds and (or) grassed waterways for transporting return flows will remove some suspended sediment from the water.

5. What Best Management Practices will minimize the turbidity problems related to irrigation water?

Generally, reduction of suspended sediment will also help to reduce turbidity. Pastures are especially effective in removing turbidity-causing material.

6. What are the impacts of ammonia concentrations from sewage-treatment- plant effluent on fish and on aquatic insects?

No direct impact of ammonia on aquatic insects was noted. Un ionized ammonia exceeded reference levels in Bear Creek several times, as did nitrite from oxidation of ammonia.

7. What is the impact of the nutrients from sewage-treatment-plant effluent on primary productivity?

Sewage-treatment-plant effluent is the primary source of nitrogen and orthophosphate to Bear Creek. These nutrients, along with the particle size of' the streambed material, are believed to control bio logical productivity.

8. To what extent do the nutrients, through biological productivity, influence the diel variations in DO and pH?

Larger diel DO and pH fluctuations appear to be associated with higher concentrations of nitrate. This does not, however, apply to sampling sites immediately below Ashland Creek (sites 102 and 108). These two sites appear to have more nitrogen available than needed, but they lack an adequate in-stream substrate to allow the growth of periphyton.

9. Do the diel variations of DO and pH have a measurable effect on fish or aquatic organisms?

No measurable effect on the aquatic organisms was detected in the data as a result of diel fluctuations in DO and pH. The methods of in situ measurement, however, are not necessarily sensitive enough to detect all effects on aquatic organisms.

10. Does the rise in temperature of irrigation water following diversion cause a significant problem for aquatic life?

No measurable effect on the aquatic organisms was detected in the data as a result of high temperatures in Bear Creek. The methods of in situ measurement, however, are not necessarily sensitive enough to detect all effects on aquatic organisms.

33

BACKGROUND

Basin Description

Bear Creek basin, about 30 mi in length, is one of many subbasins in the Rogue River drainage (fig. 12). Bear Creek flows into the Rogue River 126.8 river miles upstream from the mouth of the Rogue. The 362-square-mile drain age basin of Bear Creek has narrow mountain canyons at the upper end and is situated at the junction of the Cascade Range to the east and the Siskiyou Mountains to the southwest. The basin widens to an 8-mile delta near the confluence of Bear Creek and the Rogue River. Bear Creek begins at the con fluence of Emigrant and Neil Creeks, near the city of Ashland.

The black soils of the area resulted from the fluvial erosion and depo sition processes that formed the alluvial valley plain (Latham, 1963). Soils in the study area vary from montmorillonitic clay to granitic sandy material (Pugsley, 1972).

The climate of the basin is moderate, with moist, cool winters and, except for occasional thunderstorms, warm, dry summers. The Siskiyou Moun tains cast a rain shadow over the basin. Average annual precipitation at Medford is about 18 in.; in the higher mountains it is 40 in. or more. Most of the precipitation occurs in the fall and winter months.

Hydrologic System

Irrigation is a requirement for agriculture in the Bear Creek basin and provides much of the streamflow in late summer and early fall as a result of stored reservoir water. Current private water rights in Bear Creek basin total about 120 ft^/s--87.2 percent for irrigation of 8,200 acres, 6.8 percent for power, 2.6 percent for mining, 2.4 percent for municipal uses, and 1 percent for other uses.

To ensure a supply of water for irrigation, approximately 80,000 acre-ft of water is diverted annually from the Klamath Basin into Bear Creek basin. Fourmile Lake, Howard Prairie Lake, and Hyatt Reservoir store water which is delivered to the Bear Creek basin during the irrigation season via a series of canals and natural drainageways (see fig. 1). This water enters the basin from two points: (1) Medford Irrigation District (MID) Canal via Bradshaw Drop and (2) Green Springs diversion from Howard Prairie Reservoir to Emigrant Creek and Emigrant Reservoir above Ashland. Water is also diverted from the Little Applegate Basin via McDonald Canal to Wagner Creek and Fredrick Lateral, Table 4 shows the capacity and date of completion of the reservoirs and the irrigation districts using the stored water. The three districts serve more than 7,400 farms, with 34,500 acres under irrigation (less than 5 acres per

37

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average farm). These three districts use about 94,000 acre-ft of water annually. The large number of farm units and their small size make the dis tribution system for the irrigation districts complex.

Table 4.--Source of stored water for irrigation districts

[From Rogue Valley Council of Governments (1976) and Don Walker, Bureau of Reclamation (oral commun., March 1978]

Reservoir

Datecom

pleted

Approximateusable capacity at maximum pool

(acre-feet) Irrigation district

Fourmile Lake 1923 15,650 Rogue River Valley andFish Lake 1924 8,020 Do.Agate 1966 4,670 Do.Howard Prairie 1958 60,000 Talent.Hyatt 1922 16,180 Do.Emigrant 1924 6,000 Do.Emigrant, 1961 39,000 Do.enlarged

served

Medford

Past Investigations

In an effort to determine water-quality conditions and problems, water- quality samples have been collected since 1960 from Bear Creek and many of its tributaries. In 1960 and 1962, the Oregon State Sanitary Authority measured Bear Creek water quality. Although this study was not intensive, it indicated that the quality of water was unsuitable for most of the desired uses in Bear Creek. In a report by the U.S. Public Health Service (1965), it was concluded that, because of increases in population and industrialization, Bear Creek would need more flow to prevent further degradation of its water quality.

The U.S. Bureau of Reclamation (1966) published a report proposing to enhance flows in Bear Creek during periods of low flow and to provide addi tional water for irrigation districts during the irrigation season. The pro posal included the construction of two dams--one at Lost Creek on the Rogue River and the other on Elk Creek. Water was to be diverted from these impound ments to enhance the quality of water in Bear Creek.

A report by the Soil Conservation Service (Latham, 1963) indicated a need for correction of poor drainage caused by the clay soils. The report recom mended an improvement in irrigation techniques and mentioned the possibility of contamination of shallow wells as urbanization continued in the valley (Latham, 1963).

A study of the biological, chemical, and physical characteristics of Bear Creek in the 1968-69 period by Linn (no date) showed the following:

39

(1) The addition of Ashland Creek water tended to reduce the turbidity of Bear Creek and storm-water runoff in Medford tended to increase it, and (2) sewage-treatment-plant effluent was a source of high nitrate and orthophosphate concentrations in Bear Creek below Ashland Creek.

The U.S. Bureau of Reclamation (Pugsley, 1972) studied Emigrant Reser voir, known to be a source of turbidity for Bear Creek. Montmorillonitic clay and amorphous material that are exposed to wave action on the reservoir banks were found to be responsible for the turbidity.

Water-quality data collected by RVCOG during the 1976 water year showed the following: (1) Violation of dissolved oxygen, pH, and fecal coliform standards; (2) stream temperatures in excess of levels recommended by the Oregon Department of Fish and Wildlife for the protection of fish species; and (3) severe limitation of water use because of suspended-sediment concen trations in Ashland and Bear Creeks during the flushing of Reeder Reservoir (La Riviere, no date).

IRRIGATION-WATER ASSESSMENT

On-Farm Use

Comparison of inflow and outflow sample data shows the change in water quality resulting from irrigation of farm plots. Water samples were collected from pastures, orchards, and row crops, the three major uses of agricultural land in Bear Creek valley. Each inflow and outflow site was sampled at least once. The variability in the quality of water at each of these sampling sites is not known, but it is suspected to be significant, especially at the outflow sites. Rather than using data from a specific site, all the constituent data for each land use were considered when identifying sources or sinks and diluters or concentrators. See page 11 of the Executive Summary or the Glossary for definitions of the terms "source," "sink," "diluter," and "concentrator."

Pastures

Table 5 shows the ratio of outflow to inflow for concentrations and loads of various water-quality characteristics from pastures. Table 6 shows inflow and outflow values and other water-quality characteristics. The data were taken from table 7 of a report by Wittenberg and McKenzie (1978).

Indicator bacteria ratios show that pastures are often a source of bac terial contamination in irrigation-return flows. Increases of fecal coliform in both concentration and load are shown in figure 14. Eleven of 13 outflow samples contained concentrations of fecal coliform approaching or exceeding 1,000 bacteria/100 mL, compared to six of 13 inflow samples.

Suspended-sediment data show a decrease in concentration in nine of 13 pastures. The ground cover of the pastures reduces the velocity and energy of the water and allows the sediment to settle out. As shown in table 6, turbidity values show the same trend as suspended-sediment concentrations.

-40

Table

5,--

Rati

o of

ou

tflo

w to

in

flow

sa

mple

s for

sele

cted

wa

ter-

qual

ity

characteristics

from

pastures

[Locations of si

tes

show

n on

plate

1]

Site 50 51 54 55 61 70 73 74 78 79 81 82 83

Dis

ch

arge

0.37 -- -- -- .17

.10

1.00 .0057

-- -- .05

.13

.25

Indicator

bacteria

Feca

l coliform

Conc

en

trat

ion

4.0

1.2 .34

>2.8

Load

1.5 -- -- --

>16

>2.7

161.

6

18

18

>1.7

1.7

6.2 .76

15

1.2

>.01

-- -- .038

2.0 .30

Fecal

stre

ptoc

occi

Concen

tration

1.7

6.5

5.0 .46

Load

0.63 -- -- --

>5.0

>8.7

180 23

--

2.4

12 3.4

8.4

14

18 23

-- -- -- .17

1.1

3.5

Susp

ende

d se

dime

ntConcen

trat

ion

0.19 .32

.12

4.3 .87

.70

.37

41

2.0

8.4 .08

.37

.12

Load

0.07 -- -- -- .15

.07

.37

.23

-- -- .004

.048

.03

Diss

olve

d nitrate

Conc

en

tration

2.0 .17

.43

.06

.33

-- -- .27

.26

.39

.13

.14

.33

Load

0.74 -- -- -- .06

-- -- .002

-- -- .006

.02

.08

Tota

l Kj

elda

hl

nitrogen

Concen

trat

ion

--

0.75

1.8 .68

8.8

3.9

3.0 --

3.0 -- --

1.6

2.4

Load -- -- -- --

1.5 .39

3.0 -- -- -- -- .20

.59

Dissolved

orth

opho

spha

teConcen

tration

0.80 -- 1.0

1.9 --

3.0

10 1.2 .42

.79

.67

2.5

3.0

Load

0.30 -- -- -- -- .30

10

.007

-- -- .03

.33

.75

Tabl

e 6.

--In

flow

and

outflow

valu

es fo

r se

lect

ed water-quality characteristics

from p

astu

res

[Locations of

si

tes

show

n on plate

1]

Site 50 51 54 55 61 70 73 74 78 79 81 82 83

Temp

erat

ure

CO

Infl

ow

16 16 15.5

14 15.5

16 15 17 17.5

18.5

16.5

16 19.5

Outf

low

21 21 16 14 15.5

17.5

15 24 16 -- 16.5

25 18

Diss

olve

d oxygen

(per

cent

saturation)

Inflow 97 100 96 94 96 134 94 92 110 92 88 97 105

Outf

low

75 88 80 86 81 91 78 -- 65 -- 75 84 87

pH

(uni

ts)

Infl

ow

8.2

7.9

8.0

7.6

8.0

9.2

8.3

6.9

7.6

7.2

6.6

7.9

8.0

Outf

low

7.6

7.6

7.5

7.3

7.7

7.8

7.4 --

7.3

6.9

7.5

7.9

7.0

Specif

ic

cond

ucta

nce

(umhos/cm

at 25

°C)

Inflow

180

145

240

280

118

148

120 88

265

270

280

235

104

Outflow

200

142

315

175

126

155

124

124

275

360

280

230

175

Turbidity

(Jtu)

Infl

ow

25 25 10 50 25 25 30 15 6 7

25 15 25

Outflow

2 6 5 15 20 10 8 95 4 4 4 2 2

Nitrate data show that 10 of 11 pasture outflows contained concentrations less than did the inflows. All load values computed indicate that pastures act as sinks for this constituent. Uptake of this form of nitrogen by plants is probably the reason for the decrease in concentration. The increase shown in organic (Kjeldahl) nitrogen levels is probably due to decaying organic matter, both vegetation and fecal material, in the pastures.

Orthophosphate load data suggest that pastures act as sinks. However, data from six of 11 sets of samples show increased concentrations of orthophosphate in the outflows.

Table 6 shows variations in temperature; the significance of the vari ations has not been determined. No significant changes are detected from the data on pH or specific conductance. Dissolved-oxygen saturation levels were below 90 percent in 10 of 11 outflow samples. The probable cause of the low dissolved-oxygen saturation levels is decaying organic matter.

Cultivated Orchards

Tables 7 and 8 present ratios and values, respectively, of water-quality characteristics for cultivated orchards. Pastures were shown to be sources of bacteria, whereas orchards act as sinks, as shown in figure 13. Both, how ever, are often concentrators of indicator bacteria. Cultivated orchards con tribute more suspended sediment, turbidity, nitrate, and orthophosphate than do pastures.

Suspended-sediment concentration ratios show that cultivated orchards generally tend to increase the concentration of suspended sediment in water sampled from canals and return-flow streams; but only four of nine outflow samples contained loads greater than did the inflow samples. Soil condition, slope, application method, and discharge affect the amount of sediment in the outflow water. Turbidity data follow the same trend as data for suspended- sediment concentration.

Nitrate ratios in figure 13 show that orchards are generally concentrators

Orchards are generally sinks for orthophosphate. The concentration ratios indicate little or no change in 11 of 17 orchards sampled.

Water temperatures generally increased, as indicated in table 8. Little or no significant change was observed in pH, DO, and specific conductance.

43

Tabl

e 7. --R

atio

of

ou

tflow

to in

flow

sa

mple

s for

sele

cted

water-quality ch

arac

teri

stic

s from cu

lti

vated

orch

ards

[Locations of

si

tes

show

n on p

late 1]

Site 52 53 56 57 58 59 60 62 63 64 65 66 67 68 69 72 75

Dis

ch

arge

0.19 .41

1.2 _ _ .27

-- .037

-- -- .13

-- -- .054

.56

-- _ _ .26

Indicator

bact

eria

Fecal

coliform

Concen

trat

ion

0.25

2.6 .92

.92

1.6

2.9

1.0

3.3

2.8

3.6

2.1

6.5

12.8

5.4

4

21 2.9

Load

0.04

81.1

1.1 _ _ .43

-- .037

-- -- .47

-- -- .65

.48

-- _ _ .75

Feca

l streptococci

Conc

en

tration

0.33

2.0

10 1.2

<5.6 1.0 .10

4.7

1.1 .92

7.6

> 12

_ _ 1.9 --

4.5

4.5

Load

0.063

.82

12

_ _<1.5 -- .0

26-- -- .1

2-- -- _ _ 1.1 -- _ _ 1.2

Suspended

sediment

Concen

trat

ion

1.0 .11

75 58 100 40

.066

2.8

1.8

17 2.7

2.3

5.7

3.3

12 1.5

1.1

Load

0.19 .047

90

_ _27

-- .0024

__ --

2.2 -- -- .31

1.8 -- _ _ .29

Diss

olve

d nitrate

Concen

trat

ion

8.2

1.9

14

.15

6.9

2.1

301.

84.

2

8.1

2.2

7.4

9.8

5.9

7.2

1.5

1.4

Load

1.6 .78

17

_ _ 1.9 -- 1.1 -- -- 1.0 -- -- .53

3.3 -- _ _ .36

Diss

olve

d or

tho

pho sp

hate

Concen

trat

ion

13 2.5

1.8

1.2

1.8

1.2

2.8 .62

1.6

1.2 .35

3.0 .62

.90

1.1 .58

.68

Load

2.5

1.0

2.2 _ _ .49

-- .10

-- -- .16

-- -- .03

.50

-- _ _ .18

Table

8.--Inflow and

outf

low

valu

es for

sele

cted

wat

er-q

uali

ty ch

arac

teri

stic

s from culti-

vated

orch

ards

[Loc

atio

ns of si

tes

shown

on pl

ate

1]

Site

52 53 56 57 58 59 60 62 63 64 65 66 67 68 69 72 75

Temperature

(°C)

Infl

ow _

16--

17 16.5

23 18 17 15 15.5

20 20 18 20 12 17 17

Outflow

_ _15--

18 19 32 21--

17 17 25 18 23.5

26 25.5 _ _

19

Dissolved

oxyg

en

(per

cent

saturation)

Inflow _ _

89 --

103

102 87 104

110 98 99 --

106 _ _ 97 91 103 99

Outflow

_ _

66 --

104 99 93 100 -- 92 92 97 86 _ _ 61 92 _ _ 84

pH

(uni

ts)

Inflow

7.0

7.5 -- 7.1

7.8

7.4

7.3

7.3

8.0

8.1 --

8.1 _ _

8.0

8.0

8.1

8.2

Outflow

7.0

7.2 --

7.0

7.7

7.2

7.1

7.1

7.5

7.5 -- -- _ _

7.1

7.8

7.6

7.1

Specific

cond

ucta

nce

(umhos/cm

at 25

°C)

Infl

ow 1

Out

flow

200

165

200

215

205

200

200

220

157

190

200

196

205

360

260

260

235

240

235

270

260

168

180

146

_ _

_

260

295

250

270

290

280

280

250

Turbidity

(Jtu)

Inflow 9 25 10 30 10 10

140 15 15 10 10 10 _ _

35 20 10 20

Outf

low

15 10 35 750

400 25 20 25 25 40 25 35 _ _

35 70 15 10

4>

Ln

4>

ON

± 2

18 16 14 12 10

si 6

QC

ill

CO 1

4

Z

10 12

EX

PL

AN

AT

ION

Con

cent

ratio

n (s

olid

lin

e)

Con

cent

rato

r

Dilu

'ter

Load

(da

shed

lin

e)

Sou

rce

Sin

k

Orc

hard

s

Past

ures

FE

CA

L

CO

LIF

OR

MS

US

PE

ND

ED

SE

DIM

EN

T

Orc

hard

s

Past

ures

DIS

SO

LV

ED

NIT

RA

TE

Figu

re

13

. N

um

be

r o

f o

utf

low

/inflo

w

ratio

s (f

or

indi

vidu

al

farm

s)

show

ing

conc

entr

ator

s,

dilu

ters

, so

urce

s,

and

sink

s fo

r fe

cal

colif

orm

, su

spen

ded

sedi

tnen

t, an

d di

ssol

ved

nitr

ate

fn

past

ures

an

d or

char

ds.

Row Crops

Row crops sampled include two beet-seed fields and one grass-seed field. The beet-seed fields were adjoining, and the irrigation-return flow from one field provided a part of the inflow for the second field. The beet-seed fields had not been irrigated for 6 weeks prior to sampling, and the beet seed had been harvested 4 weeks prior to sampling. Therefore, it is possible that the large number of bacteria in the samples (see table 9) could result from a first-flush phenomenon explained by Alley (1977). The beet-seed field acted as a concentrator for suspended sediment and orthophosphate and as a sink for nitrate. Table 10 shows a significant decrease in dissolved oxygen and an increase in specific conductance from inflow to outflow in the beet-seed fields.

The grass-seed field had been harvested and part of the field burned prior to sampling. The field acted as a sink for indicator bacteria, sus pended sediment, and nitrate. This is consistent with the finding for pastures. Orthophosphate concentrations increased, and the dissolved oxygen was below 90 percent saturation.

Analysis of data from tables 5 and 7 indicates that there is a weak re lationship between discharge and loading. In general, the lower the discharge ratio, the lower the load ratio. This suggests that if outflow from the irri gated plot is kept to a minimum, the amount of material leaving the plot will also be reduced.

Irrigation-Canal-and-Stream System

The irrigation distribution system is quite complex, as seen in figure 2. The irrigation district discussions, therefore, include a sketch of each irri gation district showing sampling points. Samples were taken on a monthly basis during the 1976 irrigation season. Median values for water-quality char acteristics are listed in table 11. These values are from a report by McKenzie and Wittenberg (1977).

47

Table

9.--

Rati

o of

outflow

to inflow samples

for

sele

cted

wa

ter-

qual

ity

characteristics

from row

crops

[Locations of sites

show

n on plate

1]

Land us

e

Beet-seed

fiel

d

Do.

Gras

s-se

edfi

eld

Site 76 77 80

Dis

charge

0.13 .39

.78

Indicator

bact

eria

Fecal

coli

form

Conc

en

tration

>23 --

.54

Load

>3.0 -- .4

2

Fecal

streptococci

Conc

en

trat

ion

>17

-- .89

Load

>2.2 -- .70

Suspended

sedi

ment

Conc

en

tration

14 1.7 .41

Load

1.8 .66

.32

Dissolved

nitr

ate

Conc

en

trat

ion

3.0 .05

.34

Load

0.39 .02

.27

Dissolved

orthophosphate

Conc

en

tration

1.7

4.5

2.4

Load

0.22

1.8

1.9

00

Table

10.-

-Inf

low

and

outf

low

values for

sele

cted

wa

ter-

qual

ity

characteristics

from ro

w cr

ops

[Locations of

sites

shown

on pl

ate

1]

Land us

e

Beet

-see

d field

Do.

Grass-seed

fiel

d

Site 76 77 80

Temp

erat

ure

Inflow

17 17 15

Outflow

17 17 15

Dissolved

oxygen

(per

cent

sa

tura

tion

)Inflow

95 60 91

Outflow

38 20 76

pH

(units)

Inflow

8.0

7.4

7.6

Outflow

7.3

7.0

7.4

Spec

ific

co

nduc

tanc

e (umh

os/c

m at 25

°C)

Inflow

260

390

305

Outflow

400

600

350

Turbidity

(Jtu)

Inflow 8 10 9

Outflow

10 15 5

Table 11. -Median values of water-quality characteristics in irrigation waters of canals and streams [Locations of sites shown on plate 1]

IrrigationDistrict

TalentDo.

Do.

Do.

Do.

Do.Do.Do.

Do.

Medford

Do.

Do.

Do.Do.

Do.

Do.

Do.

Rogue RiverValley

Do.

Do.

Do.

Do.

Do.

Do.Do.

Site

No. Name

1 Ashland Lateral near Ashland2 Ashland Lateral near

downstream end3 East Lateral at Emigrant Gap

near Ashland4 Meyer Creek at South Valley

View Road5 East Lateral near downstream

end at Barnett Road6 West Lateral at Wagner Creek7 Talent Lateral near Ashland8 Lower East Lateral near

downstream end atSuncrest Road

9 Talent Lateral near downstream end at Knowles Road

10 Medford Irrigation DistrictCanal at Bradshaw Drop

1 1 Medford Irrigation DistrictCanal at Fern Valley Road

1 2 Payne Creek at Fern ValleyRoad and Medford IrrigationDistrict Canal

13 Phoenix Canal at Talent14 Phoenix Canal upstream from

Griffin Creek15 Phoenix Canal downstream

from Griffin Creek16 Phoenix Canal at Jackson

Creek17 Phoenix Canal at Old

Military Road

1 8 Rogue River Valley Canal atBradshaw Drop nearBrownsboro

19 Dry Creek downstream fromAgate Reservoir

20 Hopkins Canal upstream fromLone Pine Creek

21 Lone Pine Creek near CraterLake Avenue, Medford

22 Hopkins Canal at JohnsonStreet

23 Whetstone Creek at KirtlandRoad

24 Bear Creek Canal at Medford25 Hopkins Canal at Scenic

Avenue

-pm"

£=4

I

5

26

.83

136

1.48

7.4826.631

2.14

1.0

44

27.4

1.5630

33.6

33.5

20.2

3.18

17

25.5

1.76

9.51

2.41

1.2825

5.05

C"

SJ

R£H

15.5

20.0

15.5

16.5

20.016.518.5

18.5

21.5

16.5

19.0

17.019.0

16.0

16.0

18.5

16.0

16.5

19.5

16.5

11.5

15.0

21.021.5

19.0

ô

C T.S, 5

o 5T3 *-

1 §.S2 O.Q

102

108

10

99

113105112

97

115

111

108

96104

103

99

105

103

111

93

106

101

110

114125

88

c

ECL

7.9

8.2

7.4

7.9

8.57.97.9

7.7

8.0

7.8

7.8

7.88.0

7.8

7.7

8.0

7.9

7.8

8.0

7.9

7.6

7.7

8.38.5

7.6

5

5>% 5 .£ 3H

6

6

12

9

222111

13

16

6

22

2711

18

16

16

21

6

8

28

6

8

68

13

§c

T3

T3 0-fC^

5ôn ~"

13

9

8

19

344214

14

28

28

42

8638

51

40

39

34

28

11

41

8

18

929

40

~- l

g0 Z

8.1on °

82

85

117

298

125117185

239

178

72

128

215212

236

222

208

215

72

114

134

110

106

177236

220

T3~O

o> J

o-Sfc 2 £Q~

61

61

83

214

7676

118

185

119

66

95

124152

145

132

134

128

66

89

101

90

86

139156

158

z73

U

a'c O

> U

% Sa "

0.09

.01

.12

.25

.04

.06

.06

.57

.04

.04

.03

.18

.58

.67

.61

.54

.35

.04

.04

.05

.02

.02

.02

.44

.44

05°- j

?-!> CL C

||rB ° %

0.01

.02

.02

.04

.02

.03

.05

.14

.03

.04

.04

.04

.24

.20

.18

.15

.14

.04

.04

.06

.08

.10

.06

.18

.13

Fecalcoliform

Fecalstreptococci

Colonies/100 ml

10

68

<3

1,100

210210640

3,400

290

440

600

2,400330

1,100

920

700

840

440

6

740

260

170

160980

610

80

320

< 4

2,800

480120

2,300

7,400

2,000

550

1,600

2,900920

980

1,200

1,000

1,500

550

20

4,200

330

250

2602,000

1,200

\J In micrornhos per centimeter at 25° C.

49

\122 6ff 122 401

Site number from table 11

Natural drainage system

Irrigation distribution system

42 20-

- 42 10'

Figure 14.-Talent Irrigation District.

Talent Irrigation District

The upper end of Bear Creek basin is served by the Talent Irrigation District canals (fig. 14). The Ashland Lateral, the highest canal in the basin, has the best water quality. Little or no return flow enters the canal. One pH measurement exceeded the State standard in late September, when the pH standard also was exceeded in other canals. Temperatures of 20°C or above occurred on three occasions. Indicator-bacteria concentrations did not exceed the reference level or State standard but did show an increase in a downstream direction.

The water at a downstream site in the East Lateral, site 5, contained concentrations of indicator bacteria greater than those determined for the upstream site, site 3. No exceedance of State standards for fecal coliform occurred in the canal. The pH values were 8.5 or greater on three visits.

50

These high readings were taken during summer and occurred when DO concentra tions were at more than 100 percent saturation, indicating that photosynthetic activity was taking place in the canal. On more than one occasion, samples taken from site 5 had suspended-sediment concentrations and turbidities exceeding reference levels. Canal-bank erosion and channel scour is a possible source.

Water in the Talent Lateral at site 9 and in the Lower East Lateral at site 8 is diverted from Bear Creek at site 7, Oak Street Diversion. Bear Creek above the diversion receives irrigation-return flow from Ashland and East Laterals. Fecal coliform concentrations exceeded the State standard five of a total of 13 times sampled at sites 7, 8, and 9. Also, fecal streptococci concentrations exceeded the reference level on several occasions at all three sites. Suspended-sediment concentrations at site 8 and 9 were above reference levels five of 13 times sampled. Samples from site 8 on the Lower East Lateral had concentrations of nitrate and orthophosphate greater than that found in the water at site 7. The water in this canal is of poorer quality than the water in Ashland, East, and West Laterals. The presence of irrigation-return flow in the Talent and Lower East Laterals is, in part, responsible for the poorer quality of water in these two canals.

Meyer and Payne Creeks contain irrigation-return flow from irrigated plots being supplied by the East Lateral. Both Meyer Creek, site 4, and Payne Creek, site 12, contained concentrations of indicator bacteria higher than the State standard eight of 12 times and reference level six of nine times sampled, respectively. The bacteria probably originated from outflows of irrigated plots, failing septic systems, and wild animals.

Suspended-sediment concentrations and turbidity values each exceeded reference levels in Payne Creek five of six times sampled. The suspended sed iment is believed to come from irrigated plots and from the East Lateral. Nitrate concentrations in the irrigation-return flow streams are higher than the concentrations found in the East Lateral. The higher concentrations probably originated from outflows of ground water and from orchards, as indi cated by the data in the on-farm section of this part of the report. Data obtained prior to and after the irrigation season indicate that ground water contributes high concentrations of nitrate. During the irrigation season, the dilute irrigation water tends to reduce the concentration of nitrate.

Medford Irrigation District

The canal data for the Medford Irrigation District (MID) are listed in table 11, sites 10, 11, and 13-17. Canals under MED responsibility are shown in figure 15.

Water temperature, turbidity, and specific conductance, along with con centrations of suspended sediment and indicator bacteria , increased between site 10 and site 11 in a downstream direction. The water in the MED Canal at site 11 contains irrigation-return flow, ground water, and canal water from upstream. The quality of this water is about the same as that of the Talent Lateral.

51

\122 50" 122 40'

EXPLANATION




MILES

KILOMETERS

42 25'

Figure 15. Medford Irrigation District.

The Phoenix Canal water is diverted from Bear Creek at the Talent Di version, site 13. Additional water is siphoned across Bear Creek from MID Canal. In the Phoenix Canal, suspended sediment, nitrate, and orthophosphate concentrations are highest of any canal in the basin. The high nitrate and orthophosphate concentrations in the Phoenix Canal are probably the result of sewage-treatment-plant effluent, orchard irrigation outflow, and ground-water seepage.

Analysis of monthly data was made on the Phoenix Canal for suspended sediment, turbidity, nitrate, and orthophosphate. Figure 16 shows the plot for monthly suspended-sediment samples at five sampling sites. The suspended- sediment concentrations were highest during the first 3 months of the irrigation

52

100

90

80

£= 70O

< DC I- DC!^°O DC0 50

I £40Q Q

Q -1 iu § 30 Q

20

10

MAY JUNE JULY AUGUST SEPTEMBER

Figure 16. Suspended-sediment concentrations at selected sites in Phoenix Canal during the 1976 irrigation season.

season and then decreased for the remainder of the irrigation season. Turb idity values followed che same trend as suspended sediment. The higher con centrations of suspended sediment and levels of turbidity in the early part of the season are probably caused by (1) flushing of the irrigation distri bution network of windblown and storm-water material, (2) suspending fine material from freshly tilled fields, and (3) varying the quality of water available for irrigation because of irrigation-return flows from higher ele vations in the basin. The lesser concentrations of suspended sediment in August and September possibly resulted from higher-than-normal precipitation in August that caused reduced irrigation and irrigation-return flow. Figure 17 shows the nitrate concentrations in the samples collected in the early months. As the season progressed, the concentrations increased and then decreased toward the end of the season. The nitrate probably resulted from several sources. These include: (1) sewage-treatment-plant effluent, (2) irrigation-return flow from orchards, (3) ground-water inflow, and (4) re cycling of nutrients from dead algae.

53

Figure 17. Nitrate concentrations at selected sites in Phoenix Canal during the 1976 irrigation season.

Rogue River Valley Irrigation District

Canals operated by the Rogue River Valley Irrigation District (RRVID) are shown in figure 18. The median values for each of the water-quality character istics are listed in table 11.

Median levels of suspended sediment, turbidity, dissolved solids, and indicator bacteria for water samples taken from Hopkins Canal (on the east side of Bear Creek) above Lone Pine Creek, site 20, are larger than those for sites 18 and 19. The larger values are probably caused by irrigation-return flow. Suspended sediment, turbidity, and indicator bacteria values at site 20 each exceeded the reference levels and the State standards two or more times during the 1976 irrigation season.

Lone Pine Creek water samples were of good quality except for one fecal coliform sample that exceeded 1,000 colonies/100 mL. The water in Lone Pine Creek is similar to that in the Ashland Lateral. Most of the water in Lone Pine Creek is overflow from the Medford Aqueduct (see fig. 18). Site 22, downstream from Lone Pine Creek, reflects the introduction of clean water to

54

122 5(TI 7

122 40"

.Canal

17

EXPLANATION




42 25'

42 15'

i i2 6 KILOMETERS

Figure 18. Rogue River Valley Irrigation District.

the canal. The augmentation of flow from Lone Pine Creek into Hopkins Canal reduces the concentrations of various constituents, thereby improving the quality of the water in the canal.

The Hopkins Canal (on the west side of Bear Creek) includes water from both the Bear Creek and Hopkins Canals and is siphoned from the east side of Bear Creek. The water diverted from Bear Creek is of poor quality because of use and reuse of water for irrigation, industrial, and domestic purposes. The water is a mixture of irrigation-return flow from the East Lateral, MID Canal, and Phoenix Canal; and point discharge from outflows, such as effluent from a sewage-treatment plant.

55

Half the samples (three of six) of Hopkins Canal water at site 25 did not meet State standards for DO. Fecal coliform concentrations exceeded State standards in one of six samples. Fecal streptococci and suspended-sediment concentrations exceeded reference levels on several occasions. The Hopkins Canal water has about the same quality as that in the Phoenix Canal.

Whetstone Creek

The marsh through which Whetstone Creek flows acts as a biological puri fier. Rooted vegetation acts as a filter and aids in the settling of sus pended sediment and turbidity-causing material. Also, nutrient concentrations in the water are reduced by plant uptake. Although Whetstone, Meyer, and Payne Creeks all contain irrigation-return flow, Whetstone Creek water has lower concentrations of indicator bacteria, dissolved solids, nitrate, and suspended sediment, as well as lower values of turbidity. Irrigation-return flow is responsible for reduced dissolved-solids concentrations in both Whetstone and Meyer Creeks during the irrigation season.

Because of photosynthesis and respiration of water in the marsh, samples often had pH and DO values, respectively, outside the State standard. Water temperatures often exceeded 20°C. Water-quality characteristics of Whetstone Creek are similar to those of the tail water of the Ashland Lateral.

Comparison of Water at Points of Irrigation Diversion and Bear Creek at Kirtland Road

Analysis for each of the water-quality constituents listed in table 12 was made on the basin's irrigation-water supply (inflow) and on water leaving the Bear Creek basin (outflow). The basin's irrigation-supply water includes water that enters Bear Creek basin from the Klamath River basin and natural water of the upper Bear Creek basin. Data for the inflow sites were taken from McKenzie and Wittenberg (1977).

Bear Creek at Kirtland Road was selected to represent basin outflow because most of the water flowing from the basin passes this point. Data for Bear Creek at Kirtland Road, 1976, were taken from La Riviere (no date). Con centrations listed in table 12 are discharge-weighted means for a 5-month period, May-September. Loads were computed from the discharge-weighted mean concentrations. The values for dissolved solids from Bear Creek at Kirtland Road were calculated by using specific-conductance data and the coefficient described on page 109.

56

Tab

le 1

2.-Q

uali

ty c

hara

cter

istic

s o

f w

ater

div

erte

d fo

r ir

riga

tion

and

wat

er l

eavi

ng t

he B

ear

Cre

ek b

asin

, M

ay-S

epte

mbe

r 19

76

[Wat

er-q

ualit

y co

ncen

trat

ions

are

dis

char

ge-w

eigh

ted

mea

ns]

Site

No.

Nam

e

Dis

ch

arge

(f

t3/s

)

Mill

igra

ms

per

liter

Susp

ende

d se

dim

ent

Dis

solv

ed

solid

s

Dis

solv

ed

nitr

ate

as N

Ort

ho-

phos

phat

e as

P

Feca

l co

lifor

mFe

cal

stre

ptoc

occi

Col

onie

s/ 1

00 m

L

Irri

gatio

n di

vers

ions

1 3 7 10 18 19

Ash

land

Lat

eral

nea

r A

shla

ndE

ast

Lat

eral

at

Em

igra

nt G

ap n

ear

Ash

land

Tal

ent

Lat

eral

nea

r A

shla

ndM

edfo

rd I

rrig

atio

n D

istr

ict

Can

al a

t B

rads

haw

Dro

pR

ogue

Riv

er V

alle

y C

anal

at

Bra

dsha

w D

rop

near

Bro

wns

boro

Dry

Cre

ek d

owns

trea

m f

rom

Aga

te R

eser

voir

26 115 28 41 15 22

12 11 18 30 32 9.8

54 84 118 68 69 87

0.08 .0

9.0

8.0

6

.06

.05

0.01 .0

2.0

5.0

5

.07

.04

10 890

081

0

700 20

75 351,

700

740

1,10

0 42

Tot

al d

iver

sion

s24

7

Con

cent

ratio

n (m

g/L

)

Loa

d (t

ons/

d)

-- --

16 11

81 54

.08

.05

.03

.02

290

i/1

.8x

l01J

410

i/2.5

xl0

12

Wat

er l

eavi

ng B

ear

Cre

ek b

asin

106

Bea

r C

reek

at

Kir

tland

Roa

d

Con

cent

ratio

n

Loa

d (t

ons/

d)

150

-- --

-- 39 16

-- 144 58

-- .66

.27

-- .26

.11

--

1,20

0

-/4.4

0xl0

12

-- 2,20

0

L/8

.0xl

012

'Col

onie

s pe

r da

y.

Comparison of discharge, bacteria, suspended sediment, dissolved solids, nitrate, and orthophosphate values in irrigation water in the basin with values at Kirtland Road show the following: (1) loads are greater at Kirtland Road, (2) mean discharge at Kirtland Road equals 60 percent of irrigation- water inflows, and (3) discharge-weighted mean concentrations are two to eight times greater at Kirtland Road. The increase in concentration is caused by the use and reuse of the water for irrigation and also by industrial and municipal waste discharge. Sewage-treatment-plant effluent and ground water contribute to flow and loads at Kirtland Road. Similar data for the 1977 ir rigation season were not available. The measured discharge past Kirtland Road in 1977 ranged from 18 to 41 ft^/s. The quality of irrigation water available to the basin in 1977 was about the same as in 1976. Reduced flow past Kirtland Road would tend to reduce the load leaving the basin and would change the values as presented in table 12.

Suspended-sediment concentrations were collected from natural streams and from drains containing irrigation-return flow on the Yakima Indian Reservation in 1975 and 1976. The mean discharge-weighted concentrations for the two streams and seven drains are, respectively, 45 and 129 mg/L (Nelson, 1979). This is considerably more than the 16 and 34 mg/L in Bear Creek basin.

BEAR CREEK AND TRIBUTARIES

This unit of the report brings together all the water-quality data avail able for Bear Creek and its tributaries. Interpretation of the data helped to identify water-quality problems and their causes or sources.

A separate discussion of data at the diel sites is presented for the following reasons:

1. Early in the data-interpretation phase, the authors concluded that monitoring data, collected between 9 a.m. and 4 p.m., should not be included with the diel data collected outside this time period. The reasons for this separation of data are evident in the dissolved- oxygen and pH .discussions on Bear Creek and tributaries.

2. At the diel sites, additional chemical, physical, and biological data were obtained, which allowed more detailed interpretation at these sites.

The diel data are discussed separately following the main discussion on Bear Creek and tributaries.

Initially, the basin was divided into six subareas, each of which included a reach of Bear Creek, as shown in figure 2. These subareas, in downstream order, are called Emigrant, Ashland, Talent, Phoenix, Medford, and Central Point. The boundaries of the subareas parallel the natural drainage channels. In each subarea, at least one diel site is located near the downstream end of the Bear Creek reach. The data were divided into two hydrologic regimens, nonirrigation and irrigation, as explained on page 17. The difference in the water-quality data in the nonirrigation and irrigation

58

regimens indicates the impact of irrigation as well as the natural effects of low flows and high temperatures.

Each subarea is discussed separately in this report. Each discussion includes a summary table of median values of selected water-quality constitu ents in samples collected during the two hydrologic regimens. Tables 13 to 18 list the number of samples collected, date of collection, and source of data. Diel data are shown in separate listings: (1) data collected between 9 a.m. and 4 p.m. and (2) data collected over 24 hours.

Data for this analysis were taken from an EPA STORET retrieval made by DEQ in 1978, a Jackson County Department of Planning and Development report (La Riviere, no date), a report from Southern Oregon State College at Ashland (Linn, no date), U.S. Bureau of Reclamation files, Ashland Water Department files, and U.S. Geological Survey Bear Creek data reports (McKenzie and Wittenberg, 1977; Wittenberg and McKenzie, 1978).

Emigrant Subarea of Bear Creek Basin

The Emigrant subarea includes sites extending from Howard Prairie Reser voir to Bear Creek at Interstate 5 (river mile 24.4, as determined by the Columbia Basin Inter-Agency Committee [1967]). Table 13 contains a summary of data collected at 10 stream sites, two canal sites, and one reservoir site. During the nonirrigation regimen, water in Bear Creek at Interstate 5 site consists of (1) Emigrant Reservoir water spilled into Emigrant Creek and (2) Walker Creek and Neil Creek water. During the irrigation regimen, most of the water is diverted from Emigrant Creek into Ashland Lateral above the reservoir or is released from Emigrant Reservoir into the East Lateral and Emigrant Creek. Most of the water spilled from Emigrant Reservoir into Emigrant Creek is diverted into the Lower East and Talent Laterals downstream from Interstate Highway 5 at Oak Street diversion dam. A small volume of irrigation-return flow may be entering Bear Creek from Neil and Walker Creeks.

Interpretation of data for the Emigrant subarea, and summarized in table 13, indicates the following:

1. Median values for dissolved oxygen (DO) show little variation from site to site and from nonirrigation to irrigation regimen; most con centrations range from 110 to 95 percent of saturation. The nondiel data show that in 10 of 78 measurements, the DO was lower than 90 percent saturation (State standard). During the diel study in October 1977, 19 of 41 DO concentrations were less than the State standard.

2. The pH data for Emigrant Creek at Emigrant Road indicate four ofseven measurements exceeded the State standard. Bear Creek at Inter state Highway 5 also had four of 10 measurements, and, overall, the Emigrant subarea had 11 of 70 nondiel measurements outside the State standard of 6.5 to 8.5. The diel pH data show no measurements out side the State standards; however, they do indicate a period of high pH between 9 a.m. and 7 p.m., which coincides with the occurrence of high temperature and high DO each day.

59

Tab

le 1

3. -W

ater

-qua

lity

med

ian

valu

es f

or

the

Em

igra

nt s

ubar

ea o

f B

ear

Cre

ek b

asin

[Col

umns

adj

acen

t to

the

DO

, pH

, an

d fe

cal

colif

orm

dat

a co

lum

ns i

ndic

ate

the

num

ber

of s

ampl

es t

hat

did

not

mee

t S

tate

sta

ndar

ds,

and

the

colu

mn

adja

cent

to

the

feca

l st

rept

ococ

ci c

olum

n in

dica

tes

the

num

ber

of s

ampl

es w

ith v

alue

s gr

eate

r th

an 1

,000

col

onie

s/10

0 m

L s

ugge

sted

as

a re

fere

nce

leve

l. W

here

the

num

ber

of m

easu

rem

ents

dif

fers

fro

m t

he n

umbe

r lis

ted

unde

r "N

umbe

r of

sam

ples

col

lect

ed,"

it

is l

iste

d a

deno

min

ator

. Fu

r ex

ampl

e, 2

/3 m

eans

tw

o of

thr

ee m

easu

rem

ents

did

not

mee

t St

ate

stan

dard

s.

DS,

dow

nstr

eam

]

Site

How

ard

Prai

rie

Res

ervo

ir

Em

igra

nt C

reek

at

Gre

enSp

ring

s Po

wer

plan

t

Ash

land

lat

eral

nea

r di

vers

ion

Em

igra

nt C

reek

bel

ow

Sam

pson

Cre

ekE

mig

rant

Cre

ek a

bove

Res

ervo

ir

Eas

t la

tera

l at

Em

igra

ntG

ap b

elow

Dam

Em

igra

nt C

reek

at

outl

et

of R

eser

voir

Em

igra

nt C

reek

at

Em

igra

ntR

dN

eil

Cre

ek a

t H

ighw

ay 6

6ne

ar m

outh

Nei

l C

reek

at

Hig

hway

66

near

mou

thE

mig

rant

Cre

ek a

bove

Wal

ker

Cre

ek c

onfl

uenc

e

Bea

r C

reek

at

brid

ge t

oSc

enic

Hill

s M

emor

ial

Park

, A

shla

ndB

ear

Cre

ek a

t In

ters

tate

5

Die

l 9:

00 a

.m.-

4:00

p.m

.

Die

t al

l da

ta

Hyd

rolo

gic

regi

men

Irri

gatio

n N

on ir

riga

tion

Irri

gatio

nIr

riga

tion

Non

irri

gatio

n Ir

riga

tion

Non

irri

gatio

nIr

riga

tion

Irri

gatio

nN

on ir

riga

tion

Irri

gatio

nN

on ir

riga

tion

Irri

gatio

nN

on ir

riga

tion'

Irri

gatio

nN

on ir

riga

tion

Irri

gatio

nN

on ir

riga

tion

Irri

gatio

n

Non

irri

gatio

nIr

riga

tion

Non

irri

gatio

nIr

riga

tion

Non

irri

gatio

nIr

riga

tion

Non

irri

gatio

n Ir

riga

tion

No.

of

sam

ples

co

llect

ed

1 1 2 S 1 2 7 5 5 11

11 7 5 6 6 2 5 1 3 6 7 6 5 10 16 41 63

Dat

e of

co

llect

ion

1970

1972

19

72

1976

19

7219

7219

75-7

619

76

1976

19

7219

7219

75-7

619

7619

75-7

619

76

1972

-74

1972

-74

1972

-74

1972

-74

1968

-69

1968

-69

1975

-76

1976

1977

1977

1977

1977

Dis

solv

ed

oxyg

en

(per

cent

sa

tura

tion

)

109

0

103

0

112

010

0 0

105

0

i!40

010

7 0

110

010

2 1

90

0/1

98

0/3

- -

100

0

87

488

5

115

010

9 0

109

010

0 0

90

1999

0

PH

(uni

ts)

7.8

0

7.9

0/3

7.6

0/6

7.8

0

7.4

0/3

8.4

3/6

8.0

1

7.5

0/5

7.7

0

7.5

1/1

7.3

0/3

7.5

0

8.4

28.

4 0

7.6

1/5

8.6

3

8.0

08.

2 0

70

n

/ .O

\J

7.8

0

Spec

ific

cond

ucta

nce

(mic

rom

hos/

cm

at

25°

C)

60 82 81 74 117

212

115

130 47 198

136

830

181

222

182

645

121

665

122

Feca

l co

lifor

mFe

cal

stre

ptoc

occi

Col

onie

s/ 1

00

ml

- -

- -

10

0

33

049

0

8 0

33

05

0

180

090

0 3

<45

0 0/

11,

200

1/2

230

--

- -

- -

110

146

0 0

1100

/114

00/2

. .

..- -

- -

80

0/3

- -

13

070

0

35

0/3

- - 8

14

0

33

01,

700

5-

- _

.-

--

--

- -

-

. .

- -

33

033

0 0

2,00

0 1/

127

0 0/

2

Tur

bidi

ty

(Jtu

)

8 11 6 9 13 12 26

29 15 24

2 6

Susp

ende

d se

dim

ent

Dis

solv

ed

nitr

ate

as N

Tot

al

Kje

ldah

l ni

trog

enas

N

Dis

solv

ed

orth

o-

phos

phat

e as

P

(mg/

L)

9 12 13 16

16 6 7 839 32 6 5 4 7 3 15 18 37 6 10 4 12

-- " "

0.09 .2

1.1

4

.09

.33

.32

.42

.13

.16

.16

.28

.14

.16

.05

--

1.0

~ "

:-

0.20 .4

0

.2 .2 .2 .5 .2 .3 .3 .3 --

0.01 -- .0

7.1

2

.02

.03

.09

.07

.16

.07

.16

.02

.05

.11

.10

.06

.06

.07

.02

--

Sour

ce

OT

OIJ P

T51 U

KE

l .

U.S

. B

urea

u of

Rec

lam

atio

n fil

es.

McK

enzi

e an

d W

itten

berg

(19

77).

U.S

. B

urea

u of

Rec

lam

atio

n Ti

les.

La R

ivie

re (

no d

ate)

.

McK

enzi

e an

d W

itten

berg

(19

77)

U.S

. B

urea

u of

Rec

lam

atio

n fil

es.

La R

ivie

re (

no d

ate)

.

La R

ivie

re (

no d

ate)

.

STO

RE

T.

STO

RE

T.

Lin

n (n

o da

te).

La R

ivie

re (

no d

ate)

.

Witt

enbe

rg a

nd M

cKen

zie

(197

8).

Witt

enbe

rg a

nd M

cKen

zie

(197

8).

3. Specific-conductance values tend to increase in a downstream di rection, especially below Emigrant Reservoir. During the irrigation regimen, specific-conductance values below the reservoir were lower than during the nonirrigation regimen. Because much of the irri gation water is snowmelt and precipitation that have been stored in Emigrant, Hyatt, and Howard Prairie Reservoirs, this water has low dissolved-solids concentrations and specific-conductance values.

4. Fecal coliform concentrations generally increase in a downstream di rection during the irrigation regimen. This is considered to be the result of greater agricultural and other land-use activity in a downstream direction during the irrigation season. In 1976, the State standard was exceeded in three of 12 samples in Neil Creek and one of 11 in Bear Creek. Overall, the State standard was exceeded in five of 66 samples in the Emigrant subarea.

5. Fecal streptococci median data show the same general trend as fecal coliform data.. Concentrations exceeding 1,000 colonies per 100 mL were measured five times in Neil Creek in 1976 and once each in Bear Creek and Emigrant Creek at Emigrant Road. Emigrant subarea had a total of seven of 56 samples with concentrations above the reference level.

6. Turbidity median values show a definite increase during the irri gation regimen compared to the nonirrigation regimen. Much of the suspended material causing the turbidity downstream from Emigrant Reservoir comes from the reservoir (Pugsley, 1972). Turbidity values were noticeably low in 1977 at the Bear Creek at Interstate Highway 5 diel site, suggesting that low turbidity values correspond with periods of low flow (see fig. 26). Eight of 12 values in table 13 are less than the 15 Jtu reference level.

7. During the irrigation regimen, median concentrations of suspended sediment below Emigrant Reservoir were generally higher than during the nonirrigation regimen. The data, however, do not indicate that Emigrant Reservoir is the source of the material in suspension. Most values in table 13 are less than the 20 mg/L reference level. The low values in 1977 may, in part, result from the unusually low flows in 1977.

8. Median concentrations for dissolved nitrate show a decrease during the irrigation regimen compared to the nonirrigation regimen. Lower concentrations are possibly due to a higher rate of nitrogen uptake by periphyton growth and dilution of base flow by reservoir-water releases during the summer.

Robison (1972) published water-quality data on ground water from wells in the Emigrant subarea, and a review of these data shows the following:

61

\a. Water in five wells located outside the area under irrigation had

a mean nitrate concentration of 0.06 mg/L as N.

b. Water in five wells located within the area under irrigation had a mean nitrate concentration of 0.32 mg/L as N, 5 times the con centration for the wells outside the area under irrigation.

This seems to indicate that ground water within the irrigated area may have a greater concentration of nitrate than water outside the irrigated area, and therefore is a source of nitrate to streams. The source of nitrate in ground water is probably the infiltration of nitrate from manure, fertilizers, and domestic sewage. All concen trations in table 13 are less than the 1.0 mg/L as N reference value.

9. Total Kjeldahl nitrogen median concentrations often show an increase during the irrigation regimen compared to the nonirrigation regimen. This increase coincides with the decrease in nitrate mentioned above and with the nitrogen cycle (p.Ill), indicating an increase in organic nitrogen, possibly as periphyton.

10. Median orthophosphate concentrations often show an increase during the irrigation regimen, but the source of the increase is not known. Data for the laterals and Bear Creek at Interstate Highway 5 show very low concentrations. At other sites, median orthophosphate concen trations exceeded the 0.06 mg/L as P reference value several times.

Ashland Subarea of Bear Creek Basin

The Ashland subarea includes areas that naturally drain into Bear Creek between Interstate Highway 5 bridge (river mile 24.4) and South Valley View Road bridge near Ashland (river mile 19.9). Ashland Creek is an important tributary which carries effluent from a_ sewage-treatment plant. Canals in this subarea include the Ashland, East, West, Lower East, and Talent Laterals.

During the diel studies, sewage-treatment-plant effluent near the mouth of Ashland Creek was sampled several times in June, August, and October 1977. Median water-quantity and water-quality values include: discharge - 1.8 Mgal/d (millions of gallons per day) (2.8 ft^/s), dissolved orthophosphate as P - 8.2 mg/L, dissolved ammonia as N - 20.5 mg/L, dissolved nitrite as N - 1.7 mg/L, dissolved nitrite-plus-nitrate as N - 3.2 mg/L, total Kjeldahl nitrogen as N - 23 mg/L, TOC (total organic carbon) - 19 mg/L, COD (chemical oxygen demand) - 28 mg/L, BODU (ultimate carbonaceous biochemical oxygen demand) - 50 mg/L, specific conductance - 550 micromhos per centimeter at 25°C, and turbidity - 3 Jtu.

A summary of water-quality data for the Ashland subarea as median values, is shown in table 14. These and all other data available for the Ashland subarea show the following:

1. Dissolved-oxygen median concentrations are generally slightly higher than 100 percent saturation. One of two measurements in Butler Creek and one of 32 measurements in Bear Creek at South Valley View Road

62

Tab

le 1

4. -W

ater

-qua

lity

med

ian

valu

es f

or t

he A

shla

nd s

ubar

ea o

f B

ear

Cre

ek b

asin

[Col

umns

adj

acen

t to

the

DO

, pH

, an

d fe

cal

colif

orm

dat

a co

lum

ns i

ndic

ate

the

num

ber

of s

ampl

es t

hat

did

not

mee

t St

ate

stan

dard

s, a

nd t

he

colu

mn

adja

cent

to

the

feca

l st

rept

ococ

ci c

olum

n in

dica

tes

the

num

ber

of s

ampl

es w

ith v

alue

s gr

eate

r th

an 1

,000

col

onie

s/10

0 m

L s

ugge

sted

as

a re

fere

nce

leve

l. W

here

the

num

ber

of m

easu

rem

ents

dif

fers

fro

m t

he n

umbe

r lis

ted

unde

r "N

umbe

r of

sam

ples

col

lect

ed,"

it

is lis

ted

a de

nom

inat

or.

For

exam

ple,

2/3

mea

ns t

wo

of t

hree

mea

sure

men

ts d

id n

ot m

eet

Stat

e st

anda

rds.

D

S, d

owns

trea

m]

Site

Ash

land

Lat

eral

nea

rdo

wns

trea

m e

ndT

alen

t L

ater

al a

t di

vers

ion

near

Ash

land

Ash

land

Cre

ek a

t So

uth

Pion

eer

Stre

et i

n A

shla

ndA

shla

nd C

reek

at

Gra

nite

Stre

et,

Ash

land

Do.

Ash

land

Cre

ek a

t fi

rst

brid

geup

stre

am f

rom

Mai

n St

.,A

shla

ndA

shla

nd C

reek

at

Nev

ada

St.,

Ash

land

Do.

Ash

land

Cre

ek a

t co

nver

ttu

bes

near

ST

PD

o.

But

ler

Cre

ek a

t m

outh

Bea

r C

reek

at

Mou

ntai

n A

ve.

Die

l, 9

am- 4

pm

Die

l al

l da

ta

Bea

r C

reek

at

Oak

Str

eet

Brid

geB

ear

Cre

ek a

t Po

nder

osa

Pack

ing

Do.

Bea

r C

reek

at

Sout

h V

alle

yV

iew

Rd D

o.

Bea

r C

reek

at

Sout

h V

alle

yV

iew

Rd D

o.

Bea

r C

reek

at

Sout

h V

alle

yV

iew

Rd D

o.

Die

l, 9

am-

4 pm

Die

l, al

l da

ta

Die

l, 9

am-

4 pm

Die

l, al

l da

ta

Hyd

rolo

gic

regi

men

Irri

gatio

nIr

riga

tion

Non

irri

gatio

nIr

riga

tion

Non

irri

gatio

nir

riga

tion

Non

irri

gatio

nIr

riga

tion

Non

irri

gatio

nIr

riga

tion

Non

irri

gatio

nIr

riga

tion

Non

irri

gatio

nIr

riga

tion

Non

irri

gatio

nIr

riga

tion

Non

irri

gatio

nIr

riga

tion

Non

irri

gatio

n Ir

riga

tion

Irri

gatio

nIr

riga

tion

Irri

gatio

n N

onir

riga

tion

Irri

gatio

nN

onir

riga

tion

Irri

gatio

nN

onir

riga

tion

Irri

gatio

nN

onir

riga

tion

Irri

gatio

nN

onir

riga

tion

Irri

gatio

n

Non

irri

gatio

nIr

riga

tion

Non

irri

gatio

nIr

riga

tion

Non

irri

gatio

nIr

riga

tion

Non

irri

gatio

n Ir

riga

tion

Non

irri

gatio

n Ir

riga

tion

Non

irri

gatio

nIr

riga

tion

Irri

gatio

nIr

riga

tion

No.

of

sam

ples

colle

cted

5 5 3 2 32 30 14 23 3 2 3 6 3 2 31 30 14 23 1 1 4 3 11 1 2 35 30 20 23 6 7 35 30 20 23 3 5 2 6 3 2 9 17 41 64 3 12

Dat

e of

colle

ctio

n

1976

.197

6

1976

-77

1977

1975

-76

1976

1977

-78

1977

1976

-77

1977

1975

-76

1976

1976

-77

1977

1975

-76

1976

1977

-78

1977

1972

19

74

1969

-72

1976

1976

19

7219

72-7

4

1975

-76

1976

1977

-78

1977

1968

-69

1969

1975

-76

1976

1977

-78

1977

1975

-76

1976

1972

-74

1969

-74

1976

-77

1977

1977

19

77

1977

1977

1976

1976

Dis

solv

edox

ygen

(per

cent

satu

rati

on)

108

011

0 0

100

010

0 0

_.

-- .. -- 103

010

0 0

114

099

0

104

010

7 0

-- -- -. 81

99

010

1 0

104

0

102

0 93

0

98

0-- -- -- -- 83

4

%

3-- -- -- -- 11

4 0

99

0

84

1/1

102

0/5

104

0 10

1 0

101

0 10

0 0

on

T

>U

7

ZZ

93

19

99

0

96

0/11

PH(u

nits

)

8.2

1/3

7.8

0/4

7.9

07.

6 0

.- .. .. 7.9

07.

7 0

7.5

07.

8 0

7.9

18.

2 0

- .

-. 7.7

0 7.

7 0

8.1

08.

5 1

82

2

8.0

08.

1 0

.. -- -. -- 8.2

08.

4 0

--

..--

--

.-

---- 7.

6 0

8.0

07.

8 0/

18.

0 0/

47.

9 0

7.5

0/1

7.9

0 8.

0 0

7.6

07.

9 0

8.1

0

8.0

0

Spec

ific

cond

ucta

nce

(mic

rom

hos/

cm a

t25

° C)

85 185

150

100

-- -- -- -- 260

137

100

134

270

128

-- -- -- 700

169

194

192

280

-- -- -- -- -- -- -- -- -- -- -- 244

195

390

198

420

279

195

199

245

245

Feca

lco

lifor

mFe

cal

stre

ptoc

occi

Col

onie

s/ 1

00

ml

68

064

0 2

3 0

4 0

..

..-- ..

-.

-- 10

015

0 0

330

180

0 3

9 0

47

0-- -- -.

-.

230

042

0 0

-- --

062

0 0/

1.. -- -. -- -. .. --

--

-- .. -- 220

123

0 1

--

0/1

620

0/5 1

42

0

61

0/1

250

0/2

--

--

- -

320

0/3

2,30

0 2/

3

30 0

/228

0 0/

1..

.---

--

-.

..-- 46

0/2

510

0/1

27

095

0 3

46

0/2

650

0/1

--

----

--

-.

..-

- _

_

.-

-.

--

..--

--

..

-.-

--.

-.

--

---.

..

- -

-.

..-- -.

-.

--

----

--

-- 140

033

0 0

..

..--

--

3,40

0 1/

2 21

0/1

740

0/1

160

0/2

--

--

--

--

Tur

bidi

ty(J

tu) 6 11 2 2 8 5 2 2 1 2

-- --

1 2 3 2 3 3

-- -- 4 -- -- 6 10 4 14 15 24 8 10 4 14 -- -- -- -- 13 3 4

--

4

Susp

ende

dse

dim

ent

Dis

solv

edni

trat

eas

N

Tot

alK

jeld

ahl

nitr

ogen

as N

Dis

solv

edor

tho-

phos

phat

eas

P

(mg/

L)

9 14

1 3-- -- --

2 4 6 10 4 10 -- -- -- 25 11 -- -- -- -- -- -- -- -- -- -- -- 12 22 9 19 15

21 10

20 20 16

0.01 .0

6

.06

.04

-- -- -- -- .12

.06

.26

.21

.12

.04

-- -- -- " -- -- .04

-- -- -- -- -- -- .16

.16

-- -- -- -- .24

.46

-- -- .46

2.8

1.5 .4

6

.43

.46

-- -- 0.18 .2

8-- -- -- -- .2

8.2

0

.15

.15

.15

.22

-- -- -- " -- -- .2

-- -- -- -- -- -- -- -- -- -- 2.1

1.2 -- -- 1.7

2.0

5.3

1.9 1.3

1.3

0.02 .0

6

.09

.06

-- -- -- -- .08

.06

.08

.10

.09

.06

-- -- -- " -- .04

.18

-- " -- -- -- .11

.10

-- -- -- .45

.44

2.7

2.3

1.1

2.0

2.1 .9

8

3.5

3.2

Sour

ce

McK

enzi

e an

d W

itte

nber

g(19

77).

Do.

Witt

enbe

rg a

nd M

cKen

zie(

1978

).

Ash

land

Wat

er D

ept.

Do.

Witt

enbe

rg a

nd M

cKen

zie

(1 9

78).

La R

ivie

re (

no d

ate)

.

Witt

enbe

rg a

nd M

cKen

zie(

1978

).

Ash

land

Wat

er D

ept.

Do.

Do.

McK

enzi

e an

d W

itte

nber

gd 9

77).

Do.

STO

RE

T.

Ash

land

Wat

er D

ept.

Do.

Lin

n (n

o da

te).

Ash

land

Wat

er D

ept.

Do.

La R

ivie

re (

no d

ate)

.

STO

RE

T.

Do.

Witt

enbe

rg a

nd M

cKen

zie

(197

8).

Do.

McK

enzi

e an

d W

itten

berg

(19

77).

Do.

\failed to meet the DO State standard of 90-percent saturation. Non- die 1 DO data in Ashland subarea showed 9 of 89 measurements below State standard for DO. Of 116 diel measurements, 41 had low concen trations and occurred at night in Bear Creek at South Valley View Road.

Median pH values range from 7.5 to 8.5. Ashland Lateral and Ashland Creek at Nevada Street had 1 measurement each of 5 and 14 measurements, respectively, that exceeded the pH State standard. All the nondiel pH data in the Ashland subarea showed 5 of 84 measurements outside the State standards. Ashland Creek median data show a trend of increas ing pH in a downstream direction during the irrigation regimen.

Specific-conductance median values increase in the downstream di rection; there is also a general overall decrease during the irriga tion regimen as compared to the nonirrigation regimen. Sewage- treatment-plant effluent causes some of the increase in specific- conductance values found in the Bear Creek reach in the Ashland subarea. The general decrease during the irrigation regimen is a result of a lower concentration of dissolved solids in water coming from Emigrant Reservoir and Ashland Lateral (table 13). During the nonirrigation regimen, Emigrant Reservoir and Ashland Lateral seldom contribute water to Bear Creek. Comparison of 1976 water year data with 1977 water year data for Ashland Creek at Nevada Street and Bear Creek at South Valley View Road shows higher specific-conductance values during the 1976-77 nonirrigation regimen than during the 1975-76 nonirrigation regimen. To a lesser extent, the 1977 irriga tion regimen had higher specific-conductance values than the 1976 irri gation regimen. This is believed to be the result of the low precipi tation and resultant low streamflow during the 1977 water year.

Median fecal coliform concentrations for Ashland Creek show an increas ing trend in a downstream direction and higher concentrations during the irrigation regimen compared to the nonirrigation regimen. The waters from Bear Creek at Mountain Avenue, Bear Creek at Oak Street, and Talent Lateral have the same high concentrations because they have common sources. Concentrations decreased at the South Valley View Road site. Although a chlorine residual was never measured at this site, it is possible that residual chlorine from sewage-treatment plant effluent may have killed many bacteria that otherwise would have been in the creek. Fecal coliform concentrations were also noticeably lower during the 1977 water year than during the 1976 water year, co inciding with low streamflows. Fecal coliform concentrations exceeded State standards in the Ashland subarea as follows: 4 samples from Ashland Creek at Nevada Street, 2 samples from the Talent Lateral, and 3 samples from Bear Creek at South Valley View Road, totaling 9 of 63 samples for the whole Ashland subarea.

Fecal streptococci data show about the same general trend as do the fecal coliform data. Concentrations exceeded 1,000 colonies/100 mL 2 times in the Talent Lateral, 3 times in Ashland Creek at Nevada Street, and 1 time in Bear Creek at South Valley View Road, totaling 6 of 38 measurements.

64

6. Median turbidity values show a small but consistent trend of higher values during the irrigation regimen compared to the nonirrigation regimen and in a downstream direction. The two median values from canal sites are among the highest listed (table 14). The trend of increasing turbidities in a downstream direction is similar to that in the Emigrant subarea. During the irrigation regimen, with 17 measurements, only one median value was greater than the 15 Jtu ref erence value.

7. Median suspended-sediment concentrations in table 14 show (a) an in crease during the irrigation regimen compared to the nonirrigation regimen and (b) an increase in a downstream direction for Ashland Creek. Median suspended-sediment concentrations exceeded the 20 mg/L reference level only during the irrigation regimen.

8. Median nitrate concentrations show a definite increase in a down stream direction in both Ashland and Bear Creeks, especially below a sewage-treatment plant. The median concentrations also are less during the irrigation regimen than during the nonirrigation regimen because of dilution of stream water with irrigation water and because of uptake of nitrogen by plants. Nitrate concentrations exceeded the 1.0 mg/L reference level only in Bear Creek below a sewage-treatment plant. This exceedance and the median concentration of nitrate in sewage-treatment-plant effluent identify the effluent as a major source of nitrogen in Bear Creek. Data published by Robison (1972) on water from four wells in the irrigated area of the Ashland subarea show a mean nitrate concentration of 1.5 mg/L as N.

9. Median total Kjeldahl nitrogen concentrations show a definite in crease below a sewage-treatment-plant outfall. They do not show any significant differences between the nonirrigation and irrigation regimens.

10. Median orthophosphate concentrations show an increase at South Valley View Road and no difference in median concentrations between the nonirrigation and irrigation regimens. The median orthophosphate con centrations ranged from 0.02 to 0.18 mg/L in 12 samples collected upstream from the South Valley View Road site. The quadrupling of orthophosphate concentrations downstream from a sewage-treatment plant indicates that the treatment plant is a significant source.

Talent Subarea of Bear Creek Basin

The Talent subarea of the Bear Creek basin includes:

1. The irrigation distribution system, including East, Lower East,Talent, and West Laterals, and the Fredrick Lateral (water diverted from Wagner Creek).

2. Tributaries to Bear Creek, of which Meyer and Wagner Creeks are the most important. Wagner Creek is augmented by water diverted from the Little Applegate watershed.

65

\3. Bear Creek, extending from South Valley View Road near Ashland

(river mile 19.9) to Talent (river mile 17.2). There are no diver sions of creek water into canals in this subarea of Bear Creek.

Median values of water-quality constituents for the Talent subarea are listed in table 15. These and all other available data show the following:

1. None of the 59 nondiel DO measurements was below the State standard, but 52 of 72 diel DO measurements were below the State standard. The reason for the large number of low DO concentrations is discussed in the diel part of this report.

2. The Talent subarea had three of 60 nondiel measurements outside the State standard one in Meyer Creek and two in Wagner Creek.

3. Specific-conductance median values show (a) a definite decreaseduring the irrigation regimen compared to the nonirrigation regimen, (b) an increase in a downstream direction, and (c) an increase during the 1977 water year for Meyer Creek. In the Talent subarea, lower specific-conductance values often occur in natural creeks when they are used to convey irrigation water to small laterals. For example, table 15 shows the specific conductance of the West and East Laterals to be about equal to that of Meyer Creek during the irrigation regimen. The higher values during the 1977 water year compared to the 1976 water year are a result of low flows in 1977.

4. Fecal coliform concentrations exceeded 1,000 colonies per 100 mLtwice in Lower East Lateral, 13 times in Meyer Creek, and five times in Wagner Creek. For the entire Talent subarea, there were 20 con centrations exceeding 1,000 colonies per 100 m/L in 63 samples. The source of the bacteria in Meyer Creek is located between East Lateral and Meyer Creek Road and may be failing septic systems. During the 1976 water year, high concentrations of bacteria were found in Wagner Creek at U.S. Highway 99. During the 1977 water year, neither the Rapp Road nor U.S. Highway 99 site on Wagner Creek had high concen trations of bacteria. The few bacteria found in 1977 suggest that the problem may be related to climatic conditions and possibly to failing septic systems. The data indicated no distinct downstream or seasonal trend.

5. Fecal streptococci concentrations exceeded 1,000 colonies/100 mL two times in the Lower East Lateral, 17 times in Meyer Creek, eight times in Wagner Creek, and one time in Bear Creek, totaling 28 of 51 samples. Again, the source of the bacteria in Meyer Creek appears to be located between East Lateral and Meyer Creek Road. Although Wagner Creek showed high fecal streptococci concentrations at both sites and in different years, there is a trend toward higher counts during the irrigation regimen compared to the nonirrigation regimen, and no trend in a downstream direction.

66

Tab

le 1

5. -

Wat

er-q

ualit

y m

edia

n va

lues

for

the

Tal

ent

suba

rea

o{ B

ear

Cre

ek b

asin

[Col

umns

adj

acen

t to

the

DO

, pH

, an

d fe

cal

colif

orm

dat

a co

lum

n!,

indi

cate

the

num

ber

of s

ampl

es t

hat

did

not

mee

t St

ate

stan

dard

s, a

nd t

he

colu

mn

adja

cent

to

the

ieca

l st

rept

ococ

ci c

olum

n in

dica

tes

the

num

ber

of s

ampl

es w

ith v

alue

s gr

eate

r th

an

1,00

0 co

loni

es/1

00 m

L s

ugge

sted

as

a re

fere

nce

leve

l. W

here

the

num

ber

of m

easu

rem

ents

dif

fers

fro

m t

he n

umbe

r lis

ted

unde

r "

Num

ber

of s

ampl

es '

-olle

cted

," i

t is

liste

d as

a

deno

min

ator

, l-o

r ex

ampl

e, 2

/3 m

eans

tw

o of

thr

ee m

easu

rem

ents

did

no'

mee

t St

ate

stan

dard

s D

S, d

owns

trea

m]

Site

Wes

t la

tera

l at

Wag

ner

Cre

ekE

ast

low

lat

eral

at

Sunc

rest

Rd

Mey

er C

reek

at

Eas

t la

tera

l

Mey

er C

reek

at

Mey

er C

reek

Rd

Mey

er C

reek

at

Sout

h V

alle

yV

iew

R

d

Do.

Mey

er C

reek

at

Inte

rsta

te 5

Wag

ner

Cre

ek a

t R

app

Rd

Wag

ner

Cre

ek a

t U

.S.

Hig

hway

99

Do.

Do.

Bea

r C

reek

at

Tal

ent

Die

l, 9

am -

4 p

mD

iel

.all

data

Hyd

rolo

gic

regi

men

Irri

gatio

nIr

riga

tion

Non

irri

gatio

nIr

riga

tion

Non

irri

gatio

nIr

riga

tion

Non

irri

gatio

nIr

riga

tion

Non

irri

gatio

nIr

riga

tion

Non

irri

gatio

nIr

riga

tion

Non

irri

gatio

nIr

riga

tion

Non

irri

gatio

nIr

riga

tion

Non

irri

gatio

nIr

riga

tion

Non

irri

gatio

nIr

riga

tion

Non

irri

gatio

nIr

riga

tion

Non

irri

gatio

nIr

riga

tion

No.

of

sam

ples

co

llect

ed

5 3 1 4 1 4 1 5 2 5 2 5 3 2 3 2 5 5 2 4 8 16 24 48

Dat

e of

co

llect

ion

1976

1976

1977

1977

1977

1977

1977

1977

1976

1976

1977

1977

1976

-77

1977

1976

-77

1977

1975

-76

1976

1972

-74

1972

-74

1977

1977

1977

1977

Dis

solv

edox

ygen

(per

cent

sa

tura

tion

)

108

098

0

96

010

6 0

92

098

0

97

099

0

116

098

0

104

0/1

100

0/3

100

010

6 0

100

010

8 0

110

098

0

90

0/1

100

0/3

88

598

2

72

2186

31

r»U

pH(u

nits

)

7.9

0/4

7.7

08.

3 0

7.9

08.

0 0

7.8

08.

0 0

7.8

08.

2 0

7.9

08.

6 1

8.1

08.

1 0

8.0

18.

0 0

8.2

17.

3 0/

48.

0 0

7.5

0/1

7.9

0/3

7.8

07.

8 0

7.6

07.

6 0

Spec

ific

cond

ucta

nce

(mic

rom

hos/

cm

at

25°

C)

117

239

500

118

650

305

705

330

460

298

680

450

270

226

300

248

254

294

295

240

527

206

536

203

I-ec

alco

lifor

mfe

cal

stre

ptoc

occi

Col

onie

s/ 1

00

ml

210

0/4

3,40

0 2

70

053

0

> 2,

000

11,

300

31 ,

000

01,

900

384

0 0/

11,

100

3

700

165

0 2

160

01,

100

1

40

0--

0

170

02,

300

460

0 0/

142

0 0/

278

0/

223

0 0/

2..

----

--

120

0/4

7,40

0 2/

259

0 0

120

01,

600

15,

200

41,

300

15,

700

510

0 0

2,80

0 2/

357

0 0

2,10

0 4

230

0/1

1,60

0 1/

1

1,30

0 1/

11,

500

1/1

94

04,

900

4.. --

--

280

0/1

950

1/2

..

..--

--

Tur

bidi

ty(J

tu)

21 13 1 18 2 7 2 7 2 9 1 2 2 20 6 20 -- -- --

2-- -- --

Susp

ende

d se

dim

ent

Dis

solv

edni

trat

eas

N

Tot

alK

jeld

ahl

nitr

ogen

as

N

Dis

solv

edor

tho-

phos

phat

e as

P

(mg/

L)

42 14 3 44 112 23 128 28 22 19 76 32 1

68 10 40 6 9 8 30 820

0-- --

0.06 .5

7.0

2-- -- -- .6

9.3

2.3

4.2

5.3

6.4

9

.35

.27

.65

.38

.96

.92

.. -- 2.6 .6 -. --

-- -- 0.55 -- -- -- -- -- -- -- .4

6-- .2

0.7

6.2

5.6

6.1

6.5

0.. -- 1.

601.

20-- --

0.03 .1

4

.13

-- -- -- .06

.07

.04

.04

.04

.42

.09

.19

.10

.70

.11

.16

.07

.09

.98

.50

--

Sour

ce

McK

enzi

e an

d W

itten

berg

(197

7).

McK

enzi

e an

d W

itten

berg

( 197

7).

Witt

enbe

rg a

nd M

cKen

zie

(197

8).

Do.

Do.

McK

enzi

e an

d W

itten

berg

(197

7).

Witt

enbe

rg a

nd M

cKen

zie(

1978

).

Do.

Do.

La R

ivie

re (

no d

ate)

ST

OR

1T.

Witt

enbe

rg a

nd M

cKen

zied

978

).

Do.

\6. Median turbidity values showed a trend of higher values during the

irrigation regimen compared to the nonirrigation regimen. There was no trend of increasing turbidities in a downstream direction.

7. Except for Meyer Creek, suspended-sediment concentrations generally were higher during the irrigation regimen compared to the nonirri gation regimen, as were turbidity values. The cause of the higher concentrations for Meyer Creek in October, after irrigation was dis continued, is not known. About half the median concentrations for the Talent subarea were greater than the 20 mg/L reference level.

8. Median concentrations for nitrate were lower during the irrigationregimen compared to the nonirrigation regimen. This probably resulted from dilution by irrigation water and from uptake by plants followed by conversion of inorganic nitrogen into an organic state. During the nonirrigation regimen, the Bear Creek site exceeded the 1.0 mg/L as N reference level once.

9. Except in Bear Creek, total Kjeldahl nitrogen concentrations were higher during the irrigation regimen than during the nonirrigation regimen. These higher Kjeldahl nitrogen concentrations coincided with lower concentrations of nitrate, as noted in item 8 above. Two sources of Kjeldahl nitrogen are sewage-treatment-plant effluent, which enters all year, and dislodged periphyton in the canals and streams during the irrigation season. The decrease in Kjeldahl nitro gen concentrations in Bear Creek during the irrigation regimen show the dilution effect of irrigation water to be greater than the pro duction of Kjeldahl nitrogen by periphyton.

10. Except in Bear Creek, median orthophosphate concentrations weregreater during the irrigation season than during the nonirrigation season. This increase ranged from 0.03 to 0.96 mg/L compared to the 0.06 mg/L reference level. The median orthophosphate concentrations in Bear Creek were seven to 14 times higher than the reference level; the greatest concentrations were measured in Bear Creek at South Valley View Road. This shows the sewage-treatment-plant effluent to be a major source of orthophosphate to this subarea.

Phoenix Subarea of Bear Creek Basin

The Phoenix subarea (see fig. 2) includes parts of the East Lateral; the Medford Irrigation District (MID) and Phoenix Canals; an irrigation diversion dam on Bear Creek to provide water for the Phoenix Canal near Talent; tribu taries, including Anderson, Coleman, and Larson Creeks; and Bear Creek at Talent (river mile 17.2) to Bear Creek at Barnett Road (river mile 11.0). The MID Canal brings additional water into the basin from Little Butte Creek and augments Bear Creek water diverted into the Phoenix Canal. Because the Phoenix Canal diversion is the first downstream diversion from Ashland Creek, Phoenix Canal contains sewage-treatment-plant effluent and is rich in nutrients.

68

Median values for water-quality parameters for the Phoenix subarea are listed in table 16. These and all other available data show the following:

1. Thirteen of 146 DO measurements showed less than 90 percent sat uration. These low concentrations occurred in Payne Creek at Fern Valley Road, Anderson Creek at U.S. Highway 99, Larson Creek at North Phoenix Road, Larson Creek at Ellendale Road, Bear Creek at Suncrest Road, and Bear Creek at Barnett Road. The causes of these low con centrations are probably oxidation of organic material by bacteria and respiration of algae. Of 87 diel measurements in Bear Creek, 26 were below the State standard for DO.

2. Fifty-nine measurements of pH in this subarea exceeded the Statestandard's upper limit of 8.5. Twenty-eight of 141 nondiel measure ments made in canals, tributaries to Bear Creek, and Bear Creek, and 31 of 86 diel measurements in Bear Creek were also in excess of the State standard for pH. These data show a trend of increasing pH values in a downstream direction in the tributaries and higher pH values during the irrigation regimen compared to the nonirrigation regimen in Bear Creek. Slightly higher values were measured during the 1977 water year than during the 1976 water year.

3. Of all tributaries studied in the Phoenix subarea, specific-conductance values during the irrigation regimen are about half those during the nonirrigation regimen because of the heavy use made of the natural channels to carry irrigation and drainage water to and from farm plots. Bear Creek also has lower specific-conductance values during the irrigation regimen compared to the nonirrigation regimen. Spe cific conductance was higher during the 1977 water year than during the 1976 water year.

4. Fecal coliform concentrations in the Phoenix subarea exceeded the State standard of 1,000 colonies/100 mL in 31 of 116 measurements. Table 16 shows the sites and number of violations. Fecal coliform data indicate a trend of increasing concentrations in a downstream direction in Coleman Creek. Almost all sites have higher concen trations during the irrigation regimen compared to 'the nonirrigation regimen and fewer bacteria measured during the 1977 water year than during the 1976 water year. One source of fecal coliform appears to be irrigation-return flow, with a mean concentration of 2,700 colonies/ 100 mL for 12 outflows from farm plots in the Phoenix subarea.

5. Fecal streptococci concentrations exceeded the reference level of 1,000 colonies/100 mL in 26 of 89 measurements. The trends are similar to those for fecal coliform. One source of fecal strepto cocci in this subarea is irrigation-return flow, with a mean concen tration of 14,000 colonies/100 mL for 13 outflows from farm plots.

6. Median turbidity values are higher during the irrigation regimen com pared to the nonirrigation regimen. Because the turbidity values for tributaries are higher than those shown for canals, the source is not irrigation supply water and is probably irrigation-return flow

69

fT

able

16.

-Wat

er-q

uali

ty m

edia

n va

lues

for

the

Pho

enix

sub

area

of

Bea

r C

reek

bas

in

[Col

umns

adj

acen

t to

the

DO

, pH

, an

d fe

cal

colif

orm

dat

a co

lum

ns i

ndic

ate

the

num

ber

of s

ampl

es t

hat

did

not

mee

t St

ate

stan

dard

s, a

nd t

he

colu

mn

adja

cent

to

the

feca

l st

rept

ococ

ci c

olum

n in

dica

tes

the

num

ber

of s

ampl

es w

ith v

alue

s gr

eate

r th

an

1,00

0 co

loni

es/1

00 m

L s

ugge

sted

as

a re

fere

nce

leve

l. W

here

the

num

ber

of m

easu

rem

ents

dif

fers

fro

m t

he n

umbe

r lis

ted

unde

r "N

umbe

r of

sam

ples

col

lect

ed,"

it

is lis

ted

a de

nom

inat

or.

For

exam

ple,

2/3

mea

ns t

wo

of t

hree

mea

sure

men

ts d

id n

ot m

eet

Sta

te s

tand

ards

. D

S, d

owns

trea

m]

Site

Eas

t la

tera

l at

Bar

nctt

Rd.

(nea

r do

wns

trea

m e

nd)

Med

ford

Irr

igat

ion

Dis

tric

t(M

ID)

Can

al a

t Fe

rn V

alle

yR

dPa

yne

Cre

ek a

t Fe

rn V

alle

yR

d. (

MID

Can

al)

Phoe

nix

Can

al a

t T

alen

t

And

erso

n C

reek

at

U.S

.H

ighw

ay 9

9C

olem

an C

reek

at

Pion

eer

Rd

Col

eman

Cre

ek a

t H

oust

on R

d

Col

eman

Cre

ek a

t U

.S.

Hig

hway

99 D

o.

Col

eman

Cre

ek a

t U

.S.

Hig

hway

99

Lar

son

Cre

ek a

t N

orth

Phoe

nix

Rd

Lar

son

Cre

ek a

t K

llend

ale

Rd

Do.

Lar

son

Cre

ek a

t E

llend

ale

Rd

Bea

r C

reek

at

Inte

rsta

te5

near

San

cres

t R

d.B

ear

Cre

ek a

t Su

ncre

st R

dD

iel,

9 am

- 4

pm

dat

aD

iet,

all

data

Bea

r C

reek

nea

r Ph

oeni

xB

ear

Cre

ek a

t G

lenw

ood

Rd

Bea

r C

reek

at

Bar

nett

Rd

Do.

Bea

r C

reek

at

Bar

nett

Rd

Bea

r C

reek

at

Bar

nett

Rd

Do.

Do.

Bea

r Cre

ek a

t B

arne

tt R

d.D

iel,

9 am

- 4

pm

dat

aD

iel,

all

data

D

iel,

9 am

- 4

pm

dat

a

Die

l, al

l da

ta

Hyd

rolo

gic

regi

men

Irri

gatio

n

Irri

gatio

n

Non

irri

gatio

nIr

riga

tion

Irri

gatio

n

Non

irri

gatio

nIr

riga

tion

Non

irri

gatio

nIr

riga

tion

Non

irri

gatio

nIr

riga

tion

Non

irri

gatio

nIr

riga

tion

Non

irri

gatio

nIr

riga

tion

Non

irri

gatio

nIr

riga

tion

Non

irri

gatio

nIr

riga

tion

Non

irri

gatio

nIr

riga

tion

Non

irri

gatio

nIr

riga

tion

Non

irri

gatio

nIr

riga

tion

Non

irri

gatio

nIr

riga

tion

Irri

gatio

nIr

riga

tion

Irri

gatio

nN

onir

riga

tion

Irri

gatio

n

Non

irri

gatio

nIr

riga

tion

Non

irri

gatio

n Ir

riga

tion

Non

irri

gatio

nIr

riga

tion

Non

irri

gatio

nIr

riga

tion

Non

irri

gatio

nIr

riga

tion

Non

irri

gatio

nIr

riga

tion

Irri

gatio

nIr

riga

tion

Non

irri

gatio

nIr

riga

tion

Non

irri

gati

on

Irri

gatio

n

No.

of

sam

ples

colle

cted

5 5 1 5 5 1 6 4 1 4 1 4 1 6 5 1 2 2 1 4 1 6 5 1 2 4 5 4 10 4 4 5 34 30 20

23 6 7 4 2 4 5 4 1 3 9 17 17 25

50

Dat

e of

colle

ctio

n

1976

1976

1976

1976

1976

1976

1976

1976

-77

1977

1976

-77

1977

1976

-77

1977

1975

-76

1977

1972

1972

-74

1976

-77

1977

1976

-77

1977

1975

-76

1976

1972

1972

-74

1975

-76

1976

1976

1976

1969

-72

1975

-76

1976

1975

-76

1976

1 07

7 7

81 y

I 1

- to

1977

1968

-69

1969

1972

-75

1972

-74

1975

-76

1976

1976

-77

1977

1976

1976

19

7719

77

1977

19

77

Dis

solv

edox

ygen

(per

cent

satu

rati

on)

113

0

108

0

89

095

1

105

0

115

093

2

94

096

0

94

010

1 0

104

010

2 0

110

096

0

91

010

4 0

98

110

1 0

103

099

0

114

098

0

89

192

0

110

010

1 0

122

010

2 4

116

011

0 0

100

0-- -- -- 96

2

99

2

98 0

/211

6 0

114

011

1 0

114

011

6 0

137

0 11

3 1

136

013

6 0

%f. u

91

25

pH(u

nits

)

8.5

1

7.8

1

8.2

07.

8 0

8.0

0/4

8.8

18.

0 0

8.0

08.

2 0

7.5

08.

1 0

8.2

18.

1 0

8.0

2/5

8.0

0

8.0

08.

0 0

8.0

07.

9 0

8.4

18.

5 0

7.8

08.

0 1

8.0

07.

8 0

7.8

0/3

8.1

1

8.4

18.

2 1/

98.

7 3

7.6

08.

2 1

-- -- -- 8.6

38.

8 6

7.8

0/2

8.2

0

7.6

0/3

8.6

3

8.2

17.

8 0

9.1

3D

O

e 1

0O

.O

J/O

8.6

48.

8 12

8.0

6 8.

3 20

Spec

ific

cond

ucta

nce

(mic

rom

hos/

cm a

t25

° C

)

125

128

460

215

212

433

237

405

360

390

275

450

210

380

217

-- 267

380

104

500

190

387 97

650

-- 252

242

290

290

224

276

252

-- -- -. -- -- 370

310

292

185

400

269

178

1 71

31

to

290

302

Feca

lco

lifor

mFe

cal

stre

ptoc

occi

Col

onie

s/ 1

00

ml

210

0

600

2

1 ,90

0 1

2,40

0 4

330

0

180

074

0 1

6 0

290

027

0

460

022

0 0/

31,

900

130

0 0

1,40

0 4

600

02,

400

1/1

68

042

0 0

9 0

640

0

150

14,

900

4 02,

400

1/1

900

279

0 1

-.

-...

..

420

0/3

340

01,

100

3-.

.-

--

..

.-

-_..

..

--

--

2,30

07,

000

1/1

200

02,

200

4

20

019

0 0

-- 140

0/1

220

0/2

480

0/3

1,60

0 2/

3

1,30

0 1

2,90

0 3

920

1/3

33

070

0 2

310

0/1

850

068

0 0/

273

0 0

1,00

0 1/

21,

800

152

0

1,30

0 3

..

...-

..

- .

770

018

0 0/

294

0 0

48

03,

300

5-

--.

..

140

028

0 1

--

..-.

-.

..

..

64

049

0 1

-.

-.-- --

.-

--

..--

--

--

..--

--

55

02,

300

4

140

0/2

20

0

--

2,70

0 1/

140

0 0/

2

Tur

bidi

ty(J

tu)

22 22 2 27 11 -- --

115 2 30 2 50 -- -- -- 10 60

2 35 -- -- -- -- -- --

4

-- -- _.

--

5 11 4 14 12 25 -- -- -- --

6 20 10 2

Susp

ende

dse

dim

ent

Dis

solv

edni

trat

eas

N

Tot

alK

jeld

ahl

nitr

ogen

as N

(mg/

L)

34 42 9 86 38 6 16 144

249 4 98 4 19 -- -- 20

209 13 46 10 34 -- --

13 II 8-- 15 8 19 -- -- -- -- 16 30 8 34 11 22 32 17 14

0.04 .0

3

.72 1 Q

.1 o

.58

.81

.56

.19

.12

.46

-- .22

.58

1.1 .5

8-- -- .0

1.1

3

.02

.07

.28

.12

-- -- .50

.64

.84

-- -- .48

.61

-- -' -- 1.0 .2

5-- -- .5

4.3

7

1.1 .5

4

.14

1.9 .3

2

-- -- -- -- 0.3 .8 .1

6.2

3.2

6-- .4

6.3

5.4

2.5

0-- -- .3

8.3

5

.24

.36

.70

.06

-- -- 1.1 .6 1.2 -- -- .40

.60

-- -- -- -- -- .63

.70

.75

.47

.6 .6 .5

Dis

solv

edor

tho-

phos

phat

eas

P

0.02 .04

.06

.04

.24

.04

.31

.11

.08

.10

-- .14

.14

.12

.25

-- -- .14

.06

.05

.10

.08

.14

-- -- .34

.41

1.3 -- .1

9.1

9.2

4-- -- .4

6.4

0

.43

.25

.20

.20

.71

.89

.30

.62

.28

-

Sour

ce

McK

enzi

e an

d W

itten

berg

(19

77).

Do.

McK

enzi

e an

d W

itte

nber

g(19

77).

McK

enzi

e an

d W

itte

nber

g(19

77).

La R

ivie

re (

no d

ate)

.

Witt

enbe

rg a

nd M

cKen

zie(

1978

).

Do.

Witt

enbe

rg a

nd M

cKen

?ie(

1978

).

La R

ivie

re (

no d

ate)

.

STO

RE

T

Witt

enbe

rg a

nd M

cKcn

7ie(

1978

).

Do.

La R

ivie

re (

no d

ate)

STO

RE

T

La R

ivie

re (

no d

ate)

McK

enzi

e an

d W

itten

berg

! 19

77).

Do.

STO

RF.

T.La

Riv

iere

(no

dat

e).

Ash

land

Wat

er D

ept.

Do.

Lin

n (n

o da

te)

STO

RE

T.

La R

ivie

re (

no d

ate)

.

Do.

Do.

Do

Witt

enbe

rg a

nd M

cKen

zie

(197

8).

Do.

returning via tributaries. Most of the 15 farm plots sampled in the Phoenix subarea are orchards, and they have an average outflow tur bidity of 98 Jtu. Coleman Creek has a trend of increasing turbidity in a downstream direction. The average of the median turbidity values for a nonirrigation regimen was 4 Jtu, whereas the average of the median values for the irrigation regimen was 24 Jtu.

7. Median suspended-sediment concentrations are (a) higher in tribu taries than in Bear Creek, (b) higher in Bear Creek during the irri gation regimen compared to the nonirrigation regimen, and (c) in creasing in the downstream direction of Coleman Creek. These trends are similar to those identified for turbidity. Samples of outflows from 15 farm plots in this subarea have an average suspended-sediment concentration of 740 mg/L. Thus, a source of suspended sediment appears to be irrigation-return flow. Also, like turbidity, suspended-sediment concentrations were generally below the reference level of 20 mg/L during the nonirrigation regimen and above the ref erence level during the irrigation regimen.

8. Median concentrations of nitrate were lower during the irrigation regimen compared to the nonirrigation regimen. Only Larson Creek has low concentrations; the average of the median concentrations at three sites was about 0.11 mg/L as N during the nonirrigation regimen. These low concentrations appear to be the result of the lack of ground-water seepage during the nonirrigation regimen. In 15 outflow samples from irrigated farm plots in this subarea, the average of the median nitrate concentrations was 2.9 mg/L as N. The mean nitrate concentrations for eight wells reported by Robison (1971) is 8.6 mg/L as N. Therefore, the authors concluded that the concentrations listed in table 16 for tributaries and Bear Creek during the irri gation regimen are (a) increased by irrigation-return flows and ground-water drainage (sources) and (b) diluted by canal water. The higher concentrations during the nonirrigation than the irrigation regimen in Bear Creek are caused by sewage-treatment-plant effluent, as they are in the Talent and Ashland subareas. The higher nitrate concentrations during the nonirrigation regimen in most of the trib utaries are believed to be caused by ground-water discharge. How ever, during the nonirrigation regimen, the nitrate concentrations were generally below the reference level of 1.0 mg/L as N, except in Bear Creek.

9. Total Kjeldahl nitrogen median concentrations show a slight increase in tributaries during the irrigation regimen. This probably results from greater productivity of aquatic plants during the irrigation regimen compared to the nonirrigation regimen. The same effect was noted by P. R. Boucher and M. 0. Fretwell (U.S. Geological Survey, written commun., 1978) in Sulphur Creek basin, Washington.

10. Median orthophosphate concentrations generally are higher in tribu taries during the irrigation regimen than during the nonirrigation regimen. One source of orthophosphate is irrigation-return flow. The average orthophosphate concentration from 15 farm-plot samples in

71

Vthe Phoenix subarea is 0.25 mg/L as P. Sewage-treatment-plant effluent is a source of orthophosphate in Bear Creek during the nonirrigation regimen and to Phoenix Canal during the irrigation regimen. About 45 percent of the orthophosphate concentrations are one to four times greater than the reference level of 0.06 mg/L as P. Exceptions are East Lateral and MID Canal, which average 0.03 mg/L, and Bear Creek, which has concentrations three to 12 times greater than the reference level.

Medford Subarea of Bear Creek Basin

The Medford subarea includes the main stem of Bear Creek from Barnett Road (river mile 11.0) to Table Rock Road (river mile 6.9) (see fig. 2). Tributary inflow includes Hansen and Crooked Creeks and a log pond draining into Bear Creek near river mile 8. Water in the MID Canal at Bradshaw Drop and Agate Reservoir is conveyed into Bear Creek watershed via the Hopkins Canal. This water, plus water diverted from Bear Creek into the Bear Creek Canal, is siphoned to the west side of Bear Creek and distributed by the Hopkins Canal for irrigation.

A log-pond outflow was sampled several times in June, August, and October 1977 during the diel studies. Median water-quality concentrations in clude dissolved orthophosphate as P, 0.20 mg/L; total ammonia as N, 0.25 mg/L; dissolved nitrite as N, less than 0.02 mg/L; dissolved nitrite-plus-nitrate as N, 0.02 mg/L; total Kjeldahl nitrogen as N, 3.5 mg/L; TOG, 52 mg/L; COD, ,154 mg/L; and BODu, 66 mg/L. Discharge ranged from 10 to 75 gal/min. Turbid ity and suspended-sediment values were about 50 Jtu and 140 mg/L, respectively,

Median values for selected water-quality constituents in the Medford subarea are shown in table 17. These and all other available data show the following:

1. Fifty-five of 203 measurements did not meet the DO State standard. However, median values shown in table 17 are generally greater than 100 percent saturation. Two low concentrations on Dry Creek may be the result of withdrawing water from below a thermocline in Agate Reservoir. Other low DO concentrations occurred in Hansen Creek above Kogap Hill and Crooked Creek at U.S. Highway 99. Further analysis shows that these low DO concentrations were often from measurements made in the morning and during the 1977 water year when natural streamflow was very low (see fig. 26).

The diel data for June 1977 in Bear Creek at Table Rock Road showed a low DO of 31 percent saturation, or 2.6 mg/L. This low DO concen tration occurred when flow was extremely low and during the night. The reasons for this low DO during the diel studies are explained in the diel part of this report.

2. Sixty-five of 197 pH measurements exceeded the State standard's upper limit of 8.5, four occurring in canals, five in tributaries, and 56

72

Tab

le 1

7. -W

ater

-qua

lity

med

ian

valu

es f

or t

he M

edfo

rd s

ubar

ea o

f B

ear

Cre

ek b

asin

a ic

iere

iice

icve

i. w

nere

me

num

oer

or m

easu

rem

ents

uin

ers

irom

tne

num

oer

uste

a un

aer

Num

oer

01 s

ampl

es c

c de

nom

inat

or.

For

exam

ple,

2/3

mea

ns t

wo

of t

hree

mea

sure

men

ts d

id n

ot m

eet

Stat

e st

anda

rds.

D

S, d

owns

trea

m]

Site

Rog

ue R

iver

Val

ley

Can

al(H

opki

ns C

anal

) at

Bra

dsha

wD

rop

Dry

Cre

ek b

elow

Aga

teR

eser

voir

Hop

kins

Can

al u

pstr

eam

from

Lon

e Pi

ne C

reek

Lon

e Pi

ne C

reek

nea

r C

rate

rL

ake

Ave

. up

stre

am o

fH

opki

ns C

anal

Hop

kins

Can

al a

t Jo

hnso

n S

t

Bea

r C

reek

Can

al a

t M

edfo

rddo

wns

trea

m o

f Ja

ckso

n St

.B

ridge

Han

sen

Cre

ek a

bove

Kog

apM

ill

Han

sen

Cre

ek a

t U

.S.

Hig

hway

99

Do.

Cro

oked

Cre

ek a

t S

outh

Stag

e R

d.C

rook

ed C

reek

at

Kin

gsH

ighw

ayC

rook

ed C

reek

at

U.S

.H

ighw

ay 9

9

Do.

Bea

r C

reek

at

Mai

n St

.B

ridg

e at

Med

ford

Bea

r C

reek

at

Me A

ndre

ws

Rd.

Bea

r C

reek

at

Sta

te H

ighw

ay62

Brid

ge a

t M

edfo

rdB

ear

Cre

ek a

t S

tate

Hig

hway

62 B

ridg

e at

Med

ford

Bea

r C

reek

at

Tab

le R

ock

Rd

Bea

r C

reek

at

Tab

le R

ock

Rd.

, al

l da

taD

iel,

9 am

- 4

pm

Die

l, al

l da

taD

iel,

9 am

- 4

pm d

ata

Die

l, al

l dat

a

Hyd

rolo

gic

regi

men

Irri

gatio

n

Irri

gatio

n

Irri

gatio

nN

onir

riga

tion

Irri

gatio

n

Irri

gatio

n

Irri

gatio

n

Non

irri

gatio

nIr

riga

tion

Non

irri

gatio

nIr

riga

tion

Non

irri

gatio

nIr

riga

tion

Non

irri

gatio

nIr

riga

tion

Non

irri

gatio

nIr

riga

tion

Non

irri

gatio

nIr

riga

tion

Non

irri

gatio

nIr

riga

tion

Irri

gatio

nN

onir

riga

tion

Irri

gatio

n

Non

irri

gatio

nIr

riga

tion

Non

irri

gatio

nIr

riga

tion

Non

irri

gatio

nIr

riga

tion

Non

irri

gatio

nIr

riga

tion

Irri

gatio

n Ir

riga

tion

Non

irri

gatio

nIr

riga

tion

Non

irri

gatio

n Ir

riga

tion

No.

of

sam

ples

co

llect

ed

5 5 5 1 5 5 5 4 1 4 1 6 5 3 2 3 2 3 2 6 5 4 4 5 4 5 6 4 1 4 5 3 11 8 16 25

48

Dat

e of

colle

ctio

n

1976

1976

1976

1976

1976

1976

1976

1976

-77

1977

1976

-77

1977

1975

-76

1976

1976

-77

1977

1976

-77

1977

1976

-77

1977

1975

-76

1976

1969

-72

1975

-76

1976

1969

-72

1968

-69

1969

1976

-77

1977

1975

-76

1976

1976

1 Q

lf.

1 7/D

1977

1977

1977

19

77

Dis

solv

ed

oxyg

en(p

erce

nt

satu

rati

on)

102

0

90

2

106

110

4 0

101

0

107

0

125

089

3

%

010

9 1/

3%

0

112

011

6 1

99

095

0

108

0%

0

88

280

2

104

0%

1

122

011

0 0

103

0

128

010

2 1

112

011

0 0

130

011

3 0

103

013

2 0

103

0

136

015

0 1

89

1415

0 27

PH

(uni

ts)

7.8

1/4

8.0

1/4

7.9

18.

1 0

7.5

07.

7 0

8.5

1/4

8.0

07.

9 0

8.1

18.

0 0

7.6

1/5

8.6

28.

0 0

8.0

08.

3 1

8.2

08.

0 0

7.9

07.

7 0/

58.

0 0

8.9

37.

8 0

8.6

3

9.0

38.

8 4

9.1

48.

2 2

8.7

17.

8 0/

38.

5 3

9.4

38.

2 3/

10

8.8

68.

7 10

8.4

10

8.4

20

Spec

ific

cond

ucta

nce

(mic

rom

hos/

cm

at

25°

C)

72 114

134

106

110

106

236

1,00

021

587

522

066

823

058

024

8

600

242

400

279

364

265

238

312

226

192

,_ -- 428

243

313

225

210

217

514

298

--

Feca

l co

lifor

mFe

cal

stre

ptoc

occi

Col

onie

s/ 1

00

ml

440

1

6 0

740

2<

1 0

260

1/4

170

1

980

234

0 0/

325

0 0

250

0/3

440

020

0 0

740

210

00/2

750

1

58

0/2

720

073

0 1/

288

0 0

4,00

0 5

3,30

0 5

600

064

0 1

3,10

0 5

230

1/3

__ -- 68

081

0 0

600

13,

300

5--

--

200

0/1

320

0/2

550

1/3

20

0/3

4,20

0 1/

2<1

0

330

1/4

250

1/3

2,00

0 2/

355

0 0/

21,

600

120

0 0/

21,

300

112

0 1

1,80

0 4

360

0/2

6,90

0 1/

1

340

0/2

3,10

0 1/

13,

300

2/2

4,10

0 1/

11,

800

63,

300

5

__

..

130

0

1,30

0 4

__

-.__

.-

--

--

160

0/2

380

017

0 0

1,10

0 3

--

--

140

0/1

420

0/2

Tur

bidi

ty

(Jtu

) 6 8 28 2 6 8 8 2 35 540 __ -- 3

28 2 32 15 40 --

--

-- -- --

-- 12 28 7 20 -- 10

3

Susp

ende

d se

dim

ent

Dis

solv

edni

trat

e as

N

Tot

alK

jeld

ahl

nitr

ogen

as

N

Dis

solv

edor

iho-

ph

osph

ate

as P

(mg/

L)

28 11 412 8 18 29 67 119 15 109 12 38 5

48

9 70 310

2 12 37 32 11 28 26 __ -- 10 44 13 32 20 __ 12

0.04 .0

4

.05

.04

.02

.02

.44

2.7 .7 1.3 .6

61.

5 .94

.50

.05

.06

.14

.92

.60

.85

.39

-- .52

.39

-- .25

.07

.70

.24

.64

.52

.11

.97

.04

-- -- -- -- -- -- -- 0.42 .8

9.4

0.7

5.6

2.7

0.1

3.6

6

.38

.63

.59

2.0 .5 .7

0

-- .77

.65

-- __ -- .64

.68

.8 .70

2.0 .5 .8

0.04 .0

4

.06

.10

.08

.10

.18

.04

.17

.08

.18

.12

.36

.06

.09

.06

.12

.21

.12

.10

.24

.18

.24

.24

.17

.53

.33

.52

.47

.26

.24

.34

.38

.28

--

Sour

ce

McK

enzi

e an

d W

itten

berg

(197

7).

Do.

Do.

Do.

Do.

McK

enzi

e an

d W

itten

berg

(197

7).

Witt

enbe

rg a

nd M

cKen

zie

(197

8).

Do.

La R

ivie

re (

no d

ate)

.

Witt

enbe

rg a

nd M

cKen

zie

(197

8).

Do.

Do.

La R

ivie

re (

no d

ate)

.

STO

RE

T.

La R

ivie

re (

no d

ate)

.

STO

RE

T.

Lin

n (n

o da

te).

Witt

enbe

rg a

nd M

cKen

zie

(197

8).

La R

ivie

re (

no d

ate)

.

McK

enzi

e an

d W

itten

berg

(197

7).

McK

enzi

e an

d W

itten

berg

(197

7).

Witt

enbe

rg a

nd M

cKen

zie

(197

8).

Witt

enbe

rg a

nd M

cKen

zie

(197

8).

in the main stem of Bear Creek. Of the 56 high values in the main stem, 33 were detected during the diel studies.

3. Median specific-conductance values for Hansen and Crooked Creeks show a large decrease during the irrigation regimen, caused by the addi tion of irrigation water lower in dissolved solids. Specific- conductance values for Bear Creek were lower during the irrigation regimen than during the nonirrigation regimen. Specific conductance was generally higher in the 1977 water year than in the 1976 water year because of the lower flows and less irrigation water.

4. Fecal coliform data indicate that 34 of 106 measurements exceeded the State standard. Thirty-one of these high concentrations were detected during the 1975-76 sampling period and only two during the 1977 period. This suggests that low flows may help to control the concentrations of bacteria in streams. One obvious source of fecal coliform during the irrigation regimen is irrigation-return flow, because the average concentration of fecal coliform bacteria from nine farm plots in this subarea is 3,800 colonies/100 mL.

5. Fecal streptococci concentrations exceeded the 1,000 colonies/100 mL reference level in 36 of 80 samples collected in the Medford subarea; 29 exceedances occurred during the 1976 water year and seven in the 1977 water year. These results are similar to those for fecal coli form. The average concentration of fecal streptococci in seven out flows from farm plots is 15,000 colonies/100 mL.

6. Median turbidity values were higher during the irrigation regimen than during the nonirrigation regimen. Hansen and Crooked Creeks show a trend of higher values in a downstream direction. Sources of turbidity in Bear Creek include irrigation-return flow and a log pond. The mean turbidity of water from six outfalls of irrigated farm plots in the Hansen Creek and Crooked Creek drainages is 33 Jtu. Canals during the irrigation regimen and streams during the nonirri gation regimen generally had turbidity values of less than the refer ence level of 15 Jtu, whereas the streams during the irrigation regimen generally had water with turbidities greater than 15 Jtu.

7. Median suspended-sediment concentrations also increased during the irrigation regimen, similar to those for turbidity. Outfalls from 11 irrigated farm plots had a mean suspended-sediment concentration of 110 mg/L. These outfalls and a log pond probably are the major sources of suspended material in Bear Creek. The streams generally had less than the reference level of 20 mg/L of suspended sediment during the nonirrigation regimen, whereas the canals and streams generally had more than 20 mg/L during the irrigation regimen.

8. Median nitrate concentrations were lower during the irrigation regi men than during the nonirrigation regimen, probably due to the following:

74

a. Irrigation water of low nitrate concentration (0.04 mg/L as N) imported into the watershed during the irrigation season.

b. Ground water seeping into the streams year round (eight wells had a mean nitrate concentration of 3.2 mg/L as N [Robison, 1971]).

c. Irrigation-return flow being present during the irrigationseason, with an average nitrate concentration of 3.3 mg/L as N for 11 outfall samples from farm plots.

d. The absence of sewage-treatment-plant effluent in this reach of Bear Creek during the irrigation regimen, due to upstream diversion.

e. An increase in biological uptake of nitrate during the warm weather, which coincides with the irrigation season.

Higher nitrate concentrations in streams during winter than during summer were also found by P. R. Boucher and M. 0. Fretwell (U.S. Geo logical Survey, written commun., 1978) for the Sulphur Creek basin in Washington. The nitrate concentrations were all below the reference level of 1.0 mg/L as N except for Hansen Creek during the nonirrigation regimen.

9. Total Kjeldahl nitrogen concentrations generally were higher during the irrigation regimen than during the nonirrigation regimen, sub stantiating the uptake of nitrate by plants. P. R. Boucher and M. 0. Fretwell (U.S. Geological Survey, written commun., 1978) also showed this to be true in irrigation drains in the Sulphur Creek basin in Washington.

10. Median orthophosphate concentrations were higher during the irri gation regimen than during the nonirrigation regimen in Hansen and Crooked Creeks. The mean concentration of 11 outflow samples from irrigated farm plots in the Medford subarea was 0.29 mg/L as P. Most of the Bear Creek sites showed higher orthophosphate concentrations during the nonirrigation regimen than during the irrigation regimen. Part of this increase is due to sewage-treatment-plant effluent. Water in the canals generally had less orthophosphate than the 0.06 mg/L as P reference level, whereas tributaries had one to two times as much and Bear Creek had three to seven times as much.

Central Point Subarea of Bear Creek Basin

The Central Point subarea is in the farthest downstream part of the Bear Creek basin. This subarea also includes the farthest downstream part of the West and Talent Laterals and the Phoenix and Hopkins Canals. It includes Griffin, Jackson, and Willow Creeks, which drain into Bear Creek; and Whetstone Creek, which drains into the Rogue River. Bear and Whetstone Creeks at Kirtland Road include most of the drainage into the Rogue River from Bear Creek watershed. The drainage pattern for this subarea is illustrated in figure 2.

75

\Median values for selected water-quality constituents in the Central

Point subarea are shown in table 18. These and all other available data show the following:

1. DO concentrations were below the State standard in 54 of 273 measure ments in this subarea; 43 of the low concentrations were noted during diel studies. Most of the other low concentrations were just below the State standard and often occurred early in the morning. Also, values were generally lower during the irrigation regimen than during the nonirrigation regimen.

2. State standards for pH were exceeded in 34 of 267 measurements,always in the daytime and mostly in the afternoon. Sixteen of the values exceeding 8.5 were noted during diel studies. Bear Creek at Upton Road had five such measurements. No trends were apparent.

3. Specific-conductance median values were lower during the irrigation regimen than during the nonirrigation regimen. This is a result of dilute irrigation water mixing with natural stream water. As in the previous subareas, specific-conductance values tended to be higher in the 1977 water year than in the 1976 water year.

4. Fecal coliform concentrations exceeded the State standard in 54 of 179 measurements. Concentrations were often higher during the irri gation regimen compared to the nonirrigation regimen. Also, higher concentrations and higher flows occurred during the 1976 water year than during the 1977 water year. All samples from Whetstone Creek during the 1976 water year met the State standard. Fifty-four is the highest number of measurements to exceed the State standard in any subarea, which can be explained by (1) the large number of measure ments in the Central Point subarea and (2) the large volume of irrigation-return flow in the Central Point subarea.

5. Fecal streptococci concentrations exceeded 1,000 colonies/100 mL in 66 of 119 measurements in the Central Point subarea. The trends and sources are similar to those discussed for fecal coliform.

6. Median turbidity values were higher during the irrigation regimen than during the nonirrigation regimen, which is probably the result of irrigation-return flow entering the streams. The median values generally are below the reference level of 15 Jtu during the nonirri gation regimen and above the reference level during the irrigation regimen.

7. Median suspended-sediment concentrations were higher during the irri gation regimen than during the nonirrigation regimen. This coincides with the increase in turbidity and also is probably the result of irrigation-return flow entering the streams. The median concentra tions were generally just below the reference level of 20 mg/L during the nonirrigation regimen and well above the reference level during the irrigation regimen.

76

SltC

Talent lateral at Knowles Rd

Phoenix Canal upstream of Griffin Creek

Phoenix Canal downstream of Griffin Creek

Phoenix Canal at Jackson Creek

Phoenix Canal at Old Military Rd

Gnffin Creek al Sterling Road

Griffin Creek at West Gritl'm Rd.

Griffin Creek upstream ol South Stage Road

Griffin Creek at Bellmger Lane

Griffin Creek at Highway 238

Gnffin Creek at Ross Lane

Griffin Creek at BeaU Lane

Griffin Creek at Scenic Ave.

Do

Jackson Creek at Highway 238

Jackson Creek at BeaU Lane

Jackson Creek at Scenic Ave

Do

Bear Creek at Upton Road

Bear Creek at Vilas Road Bridge

Do

Bear Creek at Kirtland Rd.

Do.

Do

Do.

Do.

Do

Bear Creek at Kirtland Rd.

Do

Diel 9 am - 4 pm data

Diel, all data

Bear Creek >/» mile downstream of Kutland Rd.

Do.

Diel 9 am - 4 pm data

Diel all data

Whetstone Creek at Kirtland Rd.

HydrologK

Irrigation

Irrigation

Irrigation

Irrigation

Irrigation

Irrigation

Nommgation Irrigation

Nonirrtgatlon Irrigation




Irrigation


Irrigation


Nommgation

Nommgation

Irrigation

Irrigation


Nomrrigai.on Irrigation


Irrigation

Nomrrigation Irrigation


Irrigation

Irrigation

Nonimgatlon Irrigation

Irrigation

Nonimgatlon




Irrigation

No ot samples

collected

5

2 5

5

5

5

5

1

2 4

2 4

45

I 4

2 4

5 5 5 5

6 6

2

32

3 2

6 6

1 6

34 30

20 23 34 30

20 23 14 16

6 9 '5

6

8 6

4 54 1

8

23

32 30

20 23

817

12

25

Date 1)1

collection

1976

1976 1976

1976

1976

1976

1976

1977 1977

1977 1977

1977 1977

1976-77 1977

1977 1977

1977 1977

1976-77 1977

1976-77 1977

1975-76 1976

1976-77 1977

1976-77 1977

1976-77 1977

1975-76 1976

1972 1969-74

1975-76 1976

1977-78 1977

1975-76 1976

1977-78 1977 1972 1972

1972-73 1971-73 1974-75 1 974-75

1976-77 1976

1975-76 1976

1976-77 1977

1976

1976

1975-76 1976

1977-78 1977

1977 1977

1977 1977

1976 1976

Dissolved o\ >(!< " (percent

115 0

88 1 95 0

98 0

104 0

103 0

88 3

90 1 100 0

94 0 96 I

107 0 100 0

98 0 98 0

96 1 94 1

104 0 96 0

104 0 96 1

100 0 100 0

99 0 93 0

90 1 97 0

104 0 97 0

117 0 130 0

105 0 140 1/8

96 0/2 100 0

108 0/7 112 0

107 0 98 0

112 0/3 92 0

118 0

98 8/23

122 1 97 6

95 4/25 74 31/49

130 0 110 0

P H

8.0 0/4

78 0 7.8 0/4

7 7 0/4

8.0 1/4

7.9 2

7.6 1/4

8.0 0 8.4 0

8.0 0 7.6 0

8.2 0 8.0 0

7.7 1 8.0 0

7.5 077 0

7.9 0 7.9 07.6 0/5 8.0 0

8.0 0 8.4 1

7.7 0 8.0 0

7.8 1 7.9 0

7.6 0/5 7.9 0

8.5 0 9.0 6

8.2 0/2 7.6 0/4

8.1 18.0 1/3

£ °1

8.0 0 8.3 1

7.6 0/3 8.0 07.9 0/3 7.8 0

8.0 2

7.8 2/22

8.2 1 8.0 1

8.0 8/25 7.9 6/49

8.2 1 8.3 1/4

Specific

(imcromhos/

25" C)

178

168 236

222

208

215

220

460 440

380 139

335182

196225

270

420 292

499 320

420 350

380 262

215 178

309 264

355 240

352 239

250 188

270 262

299 269

312 244

286 226

279 225330 250

256

267

407 314

423 350

278177

Iccal colilorm

1 ecal

Colonies; 100 ml

290 1

2,800 3/5 1,100 I/I

920 2

700 1

840 I

610 1

60 0 1,200 1

ISO 0 320 0

170 0 450 0

60 0/3 900 1

1,200 I 750 2

350 0 690 0 690 t

1.700 3

55 0 730 1

150 2 1,200 4

270 0 300 0

200 0/2 2,600 1

1,100 2 2,200 1

2,800 5 1,500 5

600 0 550 |/4

380 0/5 230 0/1

620 1/3 4,700 4

130 0/7 910 3

920 3 790 2ISO 0720 0

200 0/1 150 0/2

180 0 160 0

2,000 2/3

310 1/3 980 0

1,200 2/3

1,000 1/3

1,500 2/3

1,200 2/3

220 0 370 0

470 0/1 1,300 3

390 0 1,200 2

920 1/3 2,800 4/4

3,100 1 2,000 3

870 0/1 3,100 3

3,000 2/3 2,300 4/4

2.200 3/4 2,200 4

360 1 2,000 5

410 0/1 1,000 0/1

1,500 I/I 2,100 2

2.100 2/2 4.500 I/I

1,400 4 2.600 5

300 1 2.300 31,400 1/2 1,300 1

440 0/1 MO 0/2

44 0260 1/3

lurbidity (Jtu)

16

618

16

16

21

13

15

1 18

1 15

6 15

5

3 1015 10 57

10 30

7 25

7 40

10

6II

11 16 16

6

7 30

10

12

4 6

Suspended sediment

28

10 51

40

39

34

40

40 13

4 24

6 49

20 23

10 2410 15

16 24

1455

8 67

4 124

17 23

30

--

44 38

18 36

10 45

12 29

18 2815 58

25

18

49

Dissolved nitrateas N

0.04

.7

.67

.61

.54

.35

.44

.01

.00

.00

.16

.54

3.31.4 2.5 1.5

1.8 1.0

.01

.25

2.0.58

2.2 .76

2.2 .97

.86 .68

.9

.6

1.1.76.87 .55

35

1.3 .32

.02

.02

Total Kjeldahl nitrogen

as N

--

0.56

.52

.68

.14

.75

78 .96 .68 .84

.6

.7

.24

.58

.55

.9

.88

.90

.8

.5

--

--

.42 .68

.4

1.6

1.0.7.81 .68

.6

"

.61.2

_.

Dissolved

phosphate as P

0 03

38 .20

.18

.15

.14

13

.05

.05

03

.08

.02

.45

.20 .47 .21

.24

.22

.08

.09

.12

.32

.13

.14

.22

.12

.20 .20

.15

.19

.14

.13.21 .17

.22

.29

.26

.13

38

--

.24

.30

.06

.06

McKen/ie jnd \\ittcnbcri; (19771

Do

Do

Da

Do

Do

Wittenberi: jnd McKen/ie (1978)

D.,

Do

Do

Do

Do

Do

Do

La Riviere (No dau-1

Wltlenbcrii and MiAciuie (1978]

Do

Uo

I j Rivitrt inn d.itc)

SIORI r

Ashland Water Dept..

Do

Ashland Water Dept.,

Do

U S. Bureau ol Reclamation files.

STORIT

Do.

Do

La Riviere (no date)

Wittenberg and McKenzie (1978)

McKenzie and Witienberg (1977).

Do Ashland Waier Dept.

Do

Wittenberg and McKenrie (1978)

Do.

McKen?ie and Wittenberg (1977).

77

8. Median nitrate concentrations of 1 to 3 mg/L as N in Griffin and Jackson Creeks during the nonirrigation regimen are less than the 5 to 8 mg/L as N from the Sulphur Creek drainage (P. R. Boucher and M. 0. Fretwell, U.S. Geological Survey, written commun., 1978). The average concentration of nitrate in water from 20 wells in this subarea is 8.0 mg/L as N; the average for six wells in the Griffin Creek and Jackson Creek drainages is 17 mg/L as N, and the average for four wells in the Whetstone drainage is 3.0 mg/L as N. These values suggest ground-water seepage could be a significant source of nitrate to streams, especially in the Griffin Creek and Jackson Creek drain ages. All concentrations are lower during the irrigation regimen than during the nonirrigation regimen. These lower concentrations result from dilution of base flow (ground-water seepage) by irri gation water and also from nitrate uptake by plants and conversion of inorganic nitrogen into organic nitrogen. The median nitrate concen trations are generally below the reference level of 1.0 mg/L as N except for Griffin Creek and Jackson Creek sites at and below Beall Lane and also Bear Creek at Kirtland Road during the nonirrigation regimen.

9. Median total Kjeldahl nitrogen concentrations generally were higher during the irrigation regimen than during the nonirrigation regimen. This agrees with the lower nitrate concentrations during the irri gation regimen and with results found by P. R. Boucher and M. 0. Fretwell (U.S. Geological Survey, written commun., 1978).

10. Median orthophosphate concentrations do not show any particular trend. Median concentrations are about one to six times the 0.06 mg/L as P reference level, and also three to 20 times the concentration con sidered necessary to support algal growths in lakes (Sawyer and McCarty, 1967).

Whetstone Creek receives irrigation-return flow and empties directly into the Rogue River upstream from the confluence of Bear Creek with the Rogue River. Upstream from the Whetstone sampling site at Kirtland Road, the creek spreads out to form a wetland area. Very slow flow and abundant vegetative growth cause the water to run through and around a "living filter." The resultant water quality in Whetstone Creek is similar to that above Emigrant Reservoir, in MID Canal at Bradshaw Drop, or in the Rogue River. In a similar situation in Wisconsin, irrigation-return flow and sewage-treatment-plant effluent pass through a swamp that acts as a polisher of the water. The swamp removed some suspended solids, turbidity, nitrogen, phosphorus, coliforms, and biochemical oxygen demand (Fetter and others, 1978). However, this practice requires land and consumes water through transpiration of the vegetation while improving water quality. A careful analysis would be needed to determine how efficient the method is for improving water quality.

Problems can also be identified with wetland areas. One concern is the potential for water-related disease in cattle that graze such wetland areas. One such water-related disease, bacillary hemoglobinuria, is caused by a bacteria species found in western areas of North America. These bacteria, during a soil phase outside of host animals, prefer (1) cattail marshes,

78

(2) hummock grasses, and (3) a soil-water environment where prolonged sat uration of an alkaline anaerobic condition exists (National Technical Advisory Committee, 1968). Several other diseases of livestock are associated with water in an anaerobic condition. Water management that prevents oxygen depletion serves to control the anaerobic condition.

Diel Sites

Each subarea previously discussed had at least one diel site. Site des ignations and year or years of data are listed, in downstream order, in table 19. (See pi. 1 for site location.)

Table 19.--List of diel sites

[Site locations shown on plate 1]

Site number

107

101

102

108

103

104

105

106

109

Bear Creek drainage subarea

Emigrant

Ashland

do.

Talent

Phoenix

do.

Medford

Central Point

do.

Site name

Bear Creek at Interstate 5 south of Ashland

Bear Creek at Mountain Avenue near Ashland

Bear Creek at South Valley View Road near Talent

Bear Creek at Talent

Bear Creek at Suncrest Road at Talent

Bear Creek at Barnett Road at Medford

Bear Creek at Table Rock Road near Medford

Bear Creek at Kirtland Road near Central Point

Bear Creek below Kirtland Road near Central Point

Year of data

collection

1977

1976

1976 and 1977

1977

1976

1976 and 1977

1976 and 1977

1976

1977

79

\A Martek Mark II and Mark V were used to collect DO, pH, temperature, and

specific conductance data; a pyrometer was used to collect solar-radiation data. These data were collected on a continuous basis for nearly 24 hours at most sites in 1977 and are reported as hourly values (Wittenberg and McKenzie, 1978, table 9). The 1976 data (McKenzie and Wittenberg, 1977, table 4) were collected at 2-hour intervals during daylight hours and twice during the night. Table 10 of the 1978 report and table 4 of the 1977 report list chemi cal and biological data for each of the diel sites.

The diel data were collected four times during the study, three times during the irrigation regimen (August 1976 and June and August 1977), and once during the nonirrigation regimen (October 1977). An example of data col lected is shown in figure 19. This figure shows that the diel fluctuations of solar radiation and dissolved oxygen have a similar relationship to time. However, water temperature, specific conductance, and pH seem to lag solar radiation by 2 to 4 hours in the daytime. Nighttime response to loss of solar radiation varied from a 1-hour lag for DO to an 11-hour lag for temperature. Both pH and specific conductance lagged by about 9 hours. Specific conduct ance decreases during a period of high solar radiation. This decrease may be caused by plant and aquatic vegetation uptake of calcium, magnesium, nitrogen, phosphorus, and other ionized constituents (Kennedy and Malcolm, 1977). The uptake of carbon by the biological system may affect the bicarbonate concen tration, in turn affecting specific-conductance values.

Dissolved Oxygen

Table 20 shows a summary of data collected during 1976 and 1977 at the diel sites, listed in downstream order. Analysis of these and other data shows the following:

1. Measurements at sites 107, 101, and 106 all met the DO State standard, except for October 17, 1977, when there was a very low discharge of 1.8 ffVs (see fig. 20) and 46 percent of the DO measurements were below the State standard. The general lack of low DO concentrations at these sites may be due to ammonia and nitrite concentrations as N being less than 0.15 and 0.02 mg/L, respectively, which probably means that nitrification was not significant.

2. At sites 102 and 108, the median DO concentration is 88 percent of saturation, and 47 percent of the measurements were below State standards. Some of the reasons for this are:

a. Mean ammonia and nitrite concentrations of 1.8 and 0.11 mg/L as N, respectively, indicate that nitrification is occurring and exerting an oxygen demand.

b. The stream bottom is mostly sand, which is not conducive to periphyton growth, as is reflected in the relatively low numbers of periphyton growing in this reach of the stream. Sites 102 and 108 had an average of about 300,000 cells per square inch compared to 9,000,000 cells per square inch in the rest of Bear Creek (see fig. 20).

80

SP

EC

IFIC

C

ON

DU

CT

AN

CE

, IN

M

ICR

OM

HO

S A

TD

ISS

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103

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Dat

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Tabl

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Dis

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11.2

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9-11

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6.2-

11.5

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9.5-

14.4

7.8-

11.7

2.

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5.8-

11.7

8.

4-14

.87.

2- 9

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7.6-

10.5

4.6-

8.3

5.

8-10

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9.4-

14.7

Perc

ent

ofsa

tura

tion

91-1

08

93-1

06

80-1

1290

-106

90-1

02

87-1

04

84-1

05

82-1

0580

-107

75

- 97

70

-93

79-1

3490

-141

75

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76

-143

91

-147

91-1

40

31-1

79

71-1

54

83-1

4980

-124

85

-120

54-1

03

67-1

28

89-1

43

Med

ian

perc

ent

of

satu

ratio

n

98

99

90 102 96

92

88

89 87

85

72 102

113 91

89

96 103 77

88

89 96

98 72

82

96

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100

perc

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satu

ratio

n(p

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f m

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rem

ents

)

38

48

29 55 18

18

16

12 33 0 0 50 56

44

40

44 55

42

46

36 50

36 8 40

44

0 0 46 0 0 8 53

52 54

75

88 40 11

48

52 0 0 58

54

56 42

27 64

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as N

BO

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7 1.

9 4.

0 .57

1.4 .9

7.2

0.1

5 .1

4 .1

6 .1

2.1

7 .2

2 .1

9 .0

5

.15

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1.0 .1

2

0.05

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5 .1

6.0

4.4

6 .6

5 .4

4 1.

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2.6 .8

4.1

4 .4

0 .2

4 1.

9 .11

.04

.04

.97

.35

.17

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1.3

2.4

3.4

3.8

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5.0

5.0

4.6

4.3

4.0

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20

6.6

4.8

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4.9

3.8

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77

56 1.8

33 20

29

29 7.8

31

43

11 32 57

22

18

23 59 2.1

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38

41

Peri

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(tho

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0 42

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680

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00

32,0

00

3. Data from sites 103, 104, 105, 106, and 109 show a wide diel range of DO and a large number of measurements below State standards. These DO characteristics are caused by:

a. Mean BODU concentrations of 9 mg/L. Data collected during this study indicate that the main sources of BODu were probably sewage-treatment-plant effluent, drainage from a log pond, and combined sewers and storm sewers in Medford.

b. Mean ammonia and nitrite concentrations of 0.25 and 0.06 mg/L,respectively, indicate that nitrification is occurring. The com bination of nitrification, oxidation of carbonaceous organic material (BODU), and respiration of aquatic vegetation at a dis charge of 2.1 ft-73 caused the very low DO concentration of 2.6 mg/L at site 105 in June (see fig. 20).

c. Periphyton cell counts averaging more than 1 million per square inch, discharges of less than 30 ft^/s, and maximum temperatures often above 25°C all cause large amounts of oxygen to be produced during periods of high solar radiation. This explains the large diel range in DO at these sites.

Figure 20 indicates that DO is not sensitive to discharge at site 107 but is sensitive at site 105, with very high maximum and very low minimum values. This may be due in part to the high periphyton population and the low discharge occurring during the irrigation season, with high solar radiation and water temperatures. The general shape of the periphyton curves and the maximum DO curves tend to indicate that there may be a cause-effect relation ship because of oxygen being a waste product of algal metabolism.

Figure 21 shows a relationship between minimum DO and BODU , as described by equation 1.

DO = 11.6 - 6.91 logio BODU (1)

where

DO = minimum DO, in milligrams per liter, and

BODu = ultimate carbonaceous biochemical oxygen demand, in milligrams per liter.

The regression equation has a correlation coefficient of 0.84.

The equation indicates that low DO concentrations are found where high BODu concentrations exist. It should not be concluded that the low DO con centrations are caused only by BODu, because nitrification is known to exist and periphyton are causing large diel variations in DO concentrations.

83

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20

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50,000

20,000

10,000

85< - 5000

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ta isocUJ

500

200

100

50

EXPLANATION

June-July data

August data

October data

107 102 108 104

1977 DIEL SITES (Direction of flow

105 109

Figure 20. Dissolved oxygen and related data at die! sites in Bear Creek basin.

84

Sampling site and number Line of best fit

3 4 5 6789 10 ULTIMATE BIOCHEMICAL OXYGEN DEMAND, IN MILLIGRAMS PER LITER

Figure 21 . Comparison of minimum dissolved oxygen with ultimate biochemical oxygendemand in Bear Creek basin.

It seems more likely that nitrification and periphyton-caused DO fluctuations coincide with sites having high BODU concentrations resulting in the minimum DO concentrations. If this is true, reduction in ammonia and BODU concentration and a reduction of growth of periphyton should raise the mini mum DO concentrations in Bear Creek.

PH

In table 21, data collected at the diel sites during 1976 and 1977 are summarized in a downstream order. The diel data indicate major differences between the upstream sites (107, 101, 102, 108, and 103) and those downstream (104, 105, 106, and 109). Upstream sites have lower periphyton cell counts and lower water temperatures than do the downstream sites. The higher numbers of periphyton at downstream sites probably indicate a stable streambed that permits algae to be attached.

Water at the upstream sites was generally within the State pH standards- only three measurements exceeded State standards in 1976, when 32 measurements were taken, and no values exceeding 8.5 were noted in 1977. At downstream sites, however, 25 percent of the measurements in 1976 and 32 percent of the measurements in 1977 indicated values that exceeded the pH State standard.

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Per

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easu

rem

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Die

l D

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ange

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Inst

anta

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s

char

ge (

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mpe

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re

rang

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Per

iphy

ton

(tho

usan

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of

cells

/in2 )

H

pa

cr a I I

50,000

EXPLANATION

O- June-July data

- August data

October data

8S5°W Q. (-

Q2<8.5

§5552"8.0 <X50

Maximum state standard

102 108 104


106 109

Figure 22. pH and related data at diel sites in Bear Creek basin.

87

Figure 22 shows a similar pattern of curves for periphyton, maximum DO, and maximum pH. Whereas solar radiation and water temperatures were quite different for the three samplings, it seems that periphyton has a dominant effect on maximum pH values and DO concentrations. No apparent relation exists between the maximum pH and DO data and the irrigation and nonirrigation season.

Figure 23 shows a comparison of the diel pH fluctuations with the diel DO fluctuations. The equation of the best-fit line is:

A pH = 0.28 + 0.149 DO (2)

where

ApH = diel pH fluctuations, in pH units, and

ADO = diel DO fluctuations, in milligrams per liter.

The regression equation has a correlation coefficient of 0.86 from 18 data sets. The data show that as the magnitude of DO fluctuations increases, the magnitude of pH fluctuations also tend to increase.

2.0

1.6

~ 1.2

I a

.8

.4

EXPLANATION

Sampling site and number

105

Line of best fit J05

104 »»104

109

J04 105

J07 J09

,109

102.

107. 1 °*/.108.107108

.102

102

2 46 8 10 12

DIEL DISSOLVED OXYGEN FLUCTUATION, IN MILLIGRAMS PER LITER

14

Figure 23. Comparison of diel pH fluctuations with diel dissolved-oxygen fluctuations in Bear Creek basin.

88

A comparison of the die! pH fluctuations with the diel temperature fluc tuations (see fig. 24) shows that data from sites 102 and 108 are more constant than the data from sites 107, 104, 105, and 109. The regression equation for sites 104, 105, 107, and 109 is:

where

ApH = 0.33 + 0.12Atemp

temp = diel temperature fluctuations, in degrees Celsius.

(3)

This regression used 12 data points and has a correlation coefficient of 0.73, Equation 3 indicates that generally the larger the magnitude of the temper ature fluctuations during 24 hours, the larger the magnitude of the pH fluc tuations for sites 107, 104, 105, and 109. Review of figure 19 and equations 2 and 3 indicates that solar radiation, in conjunction with photosynthesis and respiration of the biota, causes the fluctuations observed in pH, DO, and temperature over 24 hours.

2.0

1.6

ID.

1.2

.8

.4

EXPLANATION

J05105

Sampling site and number

Line of best fit for sites 104, 105, 107, and 109

Line of best fit for sites 102, and 108

105

108

102

J02

2 4 6 8 10 12

DIEL WATER TEMPERATURE FLUCTUATION, IN DEGREES CELSIUS

14

Figure 24. Comparison of diel pH fluctuations with diel water-temperature fluctuationsin Bear Creek basin.

89

Specific Conductance and Alkalinity

Figure 25 shows different patterns of specific conductance and alkalinity values measured during the irrigation regimen compared to the nonirrigation regimen. Whereas discharge decreased in a downstream direction during the irrigation regimen, specific conductance and alkalinity increased. A very low discharge at site 105, however, did not show a proportional increase in spe cific conductance and alkalinity, probably because the source of water is not dependent on flow during the irrigation regimen.

During the nonirrigation regimen, discharge increased and specific con ductance decreased in a downstream direction. Also, an extreme low flow at site 107 corresponded to an extreme high specific conductance value, which indicates that the source of water during the irrigation regimen is not the same for different sites. Also, during the nonirrigation regimen, alkalinity values show a slight increase from sites 102 to 105 compared to nearly equal values in specific conductance. This may be due to the sewage-treatment-plant effluent and to the increase in maximum pH in the two downstream sites (sites 104 and 105). Thus, alkalinity seems to correlate mainly with specific con ductance and, to a lesser degree, with pH. A regression analysis shows that alkalinity can be related to the specific conductance of Bear Creek water. The equation of the line of best fit is:

Alk = 28 + 0.34SC (4)

where

Alk = median alkalinity, in milligrams per liter as CaC03, and

SC = median specific conductance, in micromhos per centimeter at 25°C.

For this regression, there were 18 data points and a correlation coefficient of 0.98.

Ammonia and Nitrite

Table 22 shows dissolved nitrite and un-ionized ammonia nitrogen concen trations above the reference levels of 0.06 and 0.02 mg/L, respectively. The nitrite concentrations were above this level eight of 20 times, and the un ionized ammonia concentrations were above the reference level 13 of 30 times. The high concentrations of nitrite and un-ionized ammonia in the Ashland subarea are mostly the result of effluent from a sewage-treatment plant. The high concentrations of un-ionized ammonia in the Phoenix, Medford, and Central Point subareas are caused primarily by sewage-treatment-plant effluent in combination with low streamflows, high temperatures, and high pH values. (See Thurston and others, 1974, table 2.)

90

oCD Q DZ00

zS wwcc O w CC o-

100

50

20

10

5 -

O June-July data

D August data

October data

107 102 108 104


105 109

Figure 25. Specific conductance, alkalinity, pH, and discharge data at diel sites inBear Creek basin.

91

\Table 22.--Concentrations of ammonia and nitrite in Bear Creek during

1977 diel studies

Sitenumber

107

102

108

104

105

109

Date(1977)

6-28

8-15

10-18

6-28

8-15

10-18

6-298-1610-19

6-298-1610-19

6-308-1710-20

6-308-1710-20

Time(2400 hours)

082512451845093012401935084513001830

080012451800100012301820092012301800

124512151500

123012301400

124512001200

123012451330

Nitriteas N

(fflg/L)

<0.02<.02<.02------

<.02<.02<.02

.02

.14

.15------.07.10.27

.14--.06

.04--.08

<.02--.04

.09--.04

Ammoniaas N(mg/L)

0.07.05.10.08.07.11.12.10.08

.511.71.81.92.31.71.64.04.7

.571.4.97

.14

.16

.12

.22

.19

.05

.581.0.12

Un-ionizedammonia as N

(mg/L)

0.002.004.003.003.004.004.002.002.002

.012

.080

.081

.034

.063

.064

.016

.080

.085

.018

.048

.017

.036

.045

.014

.045

.065

.005

.016

.093

.005

92

Periphyton

Periphyton identifications for 1977 are reported by Wittenberg and McKenzie (1978, table 11). The periphyton were collected by scraping 1 square inch of periphyton growth from each of 10 rocks randomly selected in the cross section of a riffle near each site. An inverted microscope was then used to identify the algae to species, using a method described by Greeson, Ehlke, Irwin, Lium, and Slack (1977), and the results are reported as thousands of cells per square inch.

Periphyton data collected in Bear Creek in 1977 are shown in table 23. Interpretation of the data indicates the following:

1. Mean periphyton counts, water temperatures, and magnitudes of fluc tuations in DO and pH are lower in the three upstream sites (107, 102, and 108) than in the three downstream sites (104, 105, and 109) Summary data are shown below.

Parameter

Mean periphyton count (thousands of cells per square inch)

Mean water temperature (°C)

Mean dissolved oxygen fluctuations (milligrams per liter)

Mean pH fluctuations (pH units)

Sites 107, 102, 108

800

17

1.9

.5

Sites 104, 105, 109

11,000

19

5.9

1.2

2.

Some of these results are apparent in figures 23 and 24.

Navicula cryptocephala was the most dominant alga in four of 18 samples and second most dominant in two of 18 samples. A summary of 3,391 phytoplankton samples collected between 1974 and 1976 across the United States (U.S. Geological Survey files) shows Navicula to be present in 76 percent of samples. The genus Navicula was present in 100 percent of the Bear Creek samples.

93

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4. For each sample shown in table 23, the Mclntosh Diversity Index (MD) (Pielou, 1969) is calculated as shown in equation 5.

2N- nim = IT-IT- <5 >

where0 < MD < 1,

n^ = the number of individuals in the ith species, and N = the number of individuals in the sample.

As MD approaches 1, the diversity increases.The MD values at site 107 were more constant than at other sites, and the mean MD values at sites 107 and 108 were about equal. Site 104 showed the lowest mean MD, and the single lowest MD occurred at site 102 in June. The mean MD for the irrigation and nonirrigation regimens were about equal. In the June to October sampling period, site 102 showed increases in MD, whereas sites 104 and 109 showed decreases.

Benthic Invertebrates

The benthic invertebrate data were reported by Wittenberg and McKenzie (1978, table 12). The benthic invertebrates were collected from a riffle near each site using a Surber sampler covering 1 square foot of area. Identifi cation (by E. L. Quan, Oregon Dept. of Environmental Quality) was to genus, where possible, and are reported as organisms per square foot. The data are summarized in table 24. Interpretation of the table indicates the following:

1. Site 102 has the largest population of organisms, and black flies and midges are the dominant organisms. Sewage-treatment-plant effluent may influence this site because (a) both species are facul tative to organic waste and (b) the dominant organisms average 78 percent of the total at this site as compared to an average of 58 percent for the other five sites.

2. During the irrigation regimen, facultative-codominant organisms averaged 59 percent of the total organisms present; intolerant organisms averaged 27 percent. During the nonirrigation regimen, the percentage of facultative and intolerant codominants were about equal, at 41 and 42 percent, respectively. This might indicate some what better conditions in the stream for intolerant organisms during the nonirrigation regimen.

3. Midges (Chironomidae) were present in 11 of 18 samples as a dominant and averaged 56 percent of the total organisms in the 11 samples.

95

Table 24.-Summary of 1977 benthic invertebrate data from Bear Creek [Italicized names are of the genus taxonomic level]

Site

107

102

108

104

105

109

Date

6-28-77

8-15-77 10-18-77

6-28-77

8-15-77

10-18-776-29-77

8-16-77

10-19-77

6-29-77

8-16-77

10-19-77

6-30-77

8-17-77 10-20-77

6-30-77

8-17-77 10-20-77

Total number of organisms

(per square foot)

81

111 199

187

608

42261

145

241

76

166

54

128

6648

92

81 36

Dominant

Name

Chironomidae Ephemarella Baetis Hydropsyche BaetisChironomidae Simuliidae

do. Baetis SimuliidaeChironomidae Baetis Simuliidae Baetis Simuliidae BaetisChironomidae Baetis Elmidae Hydropsyche Chironomidae Baetis ChironomidaeHydropsyche Chironomidae

do. Baetis Chironomidae

do. Elmidae Hydropsyche Chironomidae

do. Baetis

or codominant organisms

Common name

Midges May flies

do. Caddis flies May fliesMidges Black flies

'do. May flies Black fliesMidges May flies Black flies May flies Black flies May fliesMidges May flies Riffle beetles Caddis flies Midges May flies MidgesCaddis flies Midges

do. May flies Midges

do. Riffle beetles Caddis flies Midges

do. May flies

Percent of

total

67 15 68 44 2068 31 79 19 8643 30 55 28 39 3941 30 28 51 31 63 2055 37 85 65 2941 23 20 76 72 19

Tolerance to organic waste!/

Facultative. Do.

Intolerant. Very tolerant.

Do.Facultative.

Do. Do.

Intolerant. Facultative.

Do.Intolerant. Facultative. Intolerant. Facultative. Intolerant.Facultative. Intolerant. Facultative. Very tolerant. Facultative. Intolerant. Facultative.Intolerant. Facultative.

Do. Intolerant. Facultative.

Do. Do.

Intolerant. Facultative.

Do. Intolerant.

!/ From Cairns and Dickson(1971), Roback (1974), Weber (1973), and E. L. Quan (Oregon Dept. of Environmental Quality, oral commun., April 12, 1978).

96

REFERENCES CITED

Alley, W. A., 1977, Guide for collection, analysis, and use of urban storm- water data: American Society of Civil Engineers, 115 p.

Bell, H. L., 1971, Effect of low pH on the survival and emergence of aquatic insects: Water Research, v. 5, p. 313-319.

Bordner, Robert, and Winter, J. A., 1978, Microbiological methods for monitor ing the environment, water, and wastes: U.S. Environmental Protection Agency, Environmental Monitoring and Support Laboratory, Office of Research and Development, 338 p.

Britton, L. J., Averett, R. C., and Ferreira, R. F., 1975, An introduction to the processes, problems, and management of urban lakes: U.S. Geo logical Survey Circular 601-K, 22 p.

Brown, E. M. , Skougstad, M. W., and Fishman, M. F., 1970, Methods for col lection and analysis of water samples for dissolved minerals and gases: U.S. Geological Survey Techniques of Water-Resources Investigations, book 5, chap. Al, 160 p.

Brown, W. M., III, Hines, W. G., Rickert, D. A., and Beach, G. L., 1979, Asynoptic approach for analyzing erosion as a guide to land-use planning: U.S. Geological Survey Circular 715-L, 45 p.

Cairns, John, Jr., and Dickson, K. L., 1971, A simple method for the bio logical assessment of the effects of waste discharges on aquatic bottom- dwelling organisms: Water Pollution Control Federal Journal, v. 43, p. 755-772.

Columbia Basin Inter-Agency Committee, Hydrology subcommittee, June 1967, River mile index, Rogue River and tributaries in Oregon: 28 p.

European Inland Fisheries Advisory Commission, 1965, Water quality criteriafor European freshwater fish, report on finely divided solids and inland fisheries: International Journal of Air and Water Pollution, v. 9, p. 151-155.

______1969, Water quality criteria for European freshwater fish--extreme pH values and inland fisheries: Prepared by European Inland Fisheries Advisory Commission Working Party on Water Quality Criteria for European freshwater fish, Water Research, v. 3, p. 593-611.

Federal Water Pollution Control Administration, 1967, Temperature and aquatic life: Federal Water Pollution Control Administration Laboratory Investi gation no. 6, Technical Advisory and Investigations Branch, Cincinnati, Ohio.

______1969, Current practices in microbiology: Federal Water PollutionControl Administration training manual, 293 p.

97

\Fetter, C. W. , Jr., Slory, W. E., and Spangler, F. L., 1978, Use of a natural

marsh for wastewater polishing: Water Pollution Control Federation Journal, v. 50, no. 2, p. 290-307.

Geldreich, E. E., 1970, Applying bacteriological parameters to recreational water quality. Journal of the American Water Works Association, v. 62, no. 2, February 1970, p. 113-120.

Greeson, P. E., Ehlke, T. A., Irwin, G. A., Lium, B. W., and Slack, K. V., 1977, Methods for collection and analysis of aquatic biological and microbiological samples: U.S. Geological Survey Techniques of Water- Resources Investigations, book 5, chap. A4, 332 p.

Guy, H. P., 1970, Fluvial sediment concepts: U.S. Geological Survey Tech niques of Water-Resources Investigations, book 3, chap. Cl, 55 p.

Guy, H. P., Norman, V. W., 1970, Field methods for measurement of fluvialsediment: U.S. Geological Survey Techniques of Water-Resources Investi gations, book 3, chap. C2, 59 p.

Hines, W. G., McKenzie, S. W. , Rickert, D. A., and Rinella, F. A., 1977, Dissolved-oxygen regimen of the Willamette River, Oregon, under con ditions of basinwide secondary treatment: U.S. Geological Survey Circular 715-1, 152 p.

Kennedy, V. C., and Malcolm, R. L., 1977, Geochemistry of the Mattole Riverin northern California: U.S. Geological Survey Open-File Report 78-205, 324 p.

Kramer, J. R. , Herbes, S. E., and Alien, H. E., 1972, Phosphorus: Analysis of water, biomass, and sediments, in. Alien, H. E., and Kramer, J. R., eds., Nutrients in natural waters: New York, Wiley-Interscience, 457 p.

Langbein, W. B., and Iseri, K. T., 1960, General introduction and hydrologic definitions: U.S. Geological Survey Water-Supply Paper 1541-A, 29 p.

La Riviere, J. R., no date, The water quality of Bear Creek and middle Rogue River basins, Basic data and preliminary water-quality assessment, October 1975 through September 1976: Jackson County Department of Planning and Development, 98 p.

La Riviere, J. R., Quan, E. L., Westgarth, W. C., and Culver, R. I., 1977, Apreliminary assessment of water quality and rural nonpoint sources in the Bear Creek basin, Jackson County, Oregon: Medford, Oreg., Rogue Valley Council of Governments publication, 38 p.

Latham, F. H., 1963, The Bear Creek valley drainage investigation: U.S. Soil Conservation Service, 37 p.

Linn, D. W., no date, A years survey (December 1968-1969) of some physical, chemical, and biological characteristics of Bear Creek, Jackson County, Oregon: Ashland, Oreg., Southern Oregon State College report, 27 p.

98

Mackenthun, K. M., 1973, Toward a cleaner aquatic environment: U.S. Environ mental Protection Agency, 273 p.

McKenzie, S. W., Wittenberg, L. A., 1977, 1976 water-quality data in BearCreek basin, Medford, Oregon: U.S. Geological Survey Open-File Report 77-90, 44 p.

National Technical Advisory Committee, 1968, Water quality criteria: Federal Water Pollution Control Administration, 234 p.

Nelson, L. M., 1979, Sediment transport by irrigation return flows on theYakima Indian Reservation, Washington, 1975 and 1976 irrigation seasons: U.S. Geological Survey Open-File Report 78-947, 42 p.

Oregon Department of Environmental Quality, 1977, Regulations relating to water quality control in Oregon, Sections from Oregon Administrative Rules, chapter 340: Oregon Department of Environmental Quality.

Oregon State Health Division, 1976, Water quality standards: Oregon Admini strative Rules, chap. 333, sec. 42-210, subsec. 2A.

Palmer, C. M. , 1968, A composite rating of algae tolerating organic pollution: Presented at symposium sponsored by Phycological Society of America and the Phycological Section, Botanical Society of America, Columbus, Ohio, September 1968, p. 78-82.

Pickering, R. J., 1976, Measurement of "turbidity" and related character istics of natural waters: U.S. Geological Survey Open-File Report 76-153, 7 p.

Pielou, E. C., 1969, An introduction to mathematical ecology: New York, Wiley-Interscience.

Pugsley, J. A., 1972, Turbidity of Emigrant Reservoir: U.S. Bureau of Rec lamation, 20 p.

Rickert, D. A., Kennedy, V. C., McKenzie, S. W., and Hines, W. G., 1977a, A synoptic survey of trace metals in bottom sediments of the Willamette River, Oregon: U.S. Geological Survey Circular 715-F, 27 p.

Rickert, D. A., Peterson, R. R., McKenzie, S. W., Hines, W. G., and Wille,S. A., 1977b, Algal conditions and the potential for future algal prob lems in the Willamette River, Oregon: U.S. Geological Survey Circular 715-G, 39 p.

Rickert, D. A., Hazen, H. H., Jackson, J. E., Anderson, D. M. , Beach, G. L., Suwijn, Elizabeth, and Benton, E. T., 1978a, Oregon's statewide assess ment of nonpoint source problems: Portland, Oregon Department of Environmental Quality, 71 p.

99

Rickert, D. A., Beach, G. L., Jackson, J. E., Anderson, D. M., Hazen, H. H., and Suwijn, Elizabeth, 1978b, Oregon's procedure for assessing the impacts of land management activities on erosion related nonpoint source problems: Portland, Oregon Department of Environmental Quality, 219 p.

Roback, S. S., 1974, Chapter 10, Insects (Arthropoda: Insecta), in HartC. W., Jr., and Fuller, S. L. H., eds., Pollution ecology of freshwater invertebrates: New York, San Francisco, Academic Press, p. 313-376.

Robison, J. H., 1971, Availability and quality of ground water in the Medford area, Jackson County, Oregon: U.S. Geological Survey Hydrologic Investi gations Atlas HA-392.

______1972, Availability and quality of ground water in the Ashland quadrangle, Jackson County, Oregon: U.S. Geological Survey Hydrologic In vestigations Atlas HA-421.

Rogue Valley Council of Governments, 1976, Water quality management planning resource inventory: Medford, Oreg., Rogue Valley Council of Governments publication, 182 p.

Sawyer, C. N., and McCarty, P. L., 1967, Chemistry for sanitary engineers: New York, McGraw-Hill, 518 p.

Schindler, D. W., 1971, Carbon, nitrogen, and phosphorus and the eutrophi- cation of freshwater lakes: Journal of Phycology, v. 7, no. 4, p. 321-329.

Somerville, J. E., 1977, City of Ashland, Oregon, water resources plan and facilities study: James M. Montgomery, Consulting Engineers, Incor porated, approximately 200 p.

Stevens, H. H., Jr., Ficke, J. F., Smoot, G. F., 1975, Water temperature- influential factors, field measurement, and data presentation: U.S. Geologica-1 Survey Techniques of Water-Resources Investigations, book 1, chap. Dl, 65 p.

Stumm, Werner, and Morgan, J. J., 1970, Aquatic chemistry: New York, Wiley- Interscience, 583 p.

Thurston, R. V., Russo, R. C., and Emerson, Kenneth, 1974 (revised 1977),Aqueous ammonia equilibrium calculations: Bozeman, Montana State Uni versity, Fisheries Bioassay Laboratory, Technical report no. 74-1, 20 p.

U.S. Bureau of Reclamation, 1966, Medford Division, Rogue River basin project, Oregon: Boise, Idaho, U.S. Bureau of Reclamation, 79 p.

U.S. Environmental Protection Agency, 1976, Quality criteria for water: U.S. Environmental Protection Agency, 256 p.

100

U.S. Public Health Service, 1965, Water quality control study, Rogue Riverbasin, Oregon, Medford Division, Bear Creek: Portland, Oreg., U.S.Public Health Service, 31 p.

Velz, C. J., 1970, Applied stream sanitation: New York, John Wiley, 619 p.

Weber, C. I., ed., 1973, Biological field and laboratory methods for measur ing the quality of surface waters and effluents: U.S. Environmental Protection Agency, Environmental Monitoring Series, EPA-670/4-73-001-.

Wittenberg, L. A., 1978, Storm-water data for Bear Creek basin, JacksonCounty, Oregon, 1977-78: U.S. Geological Survey Open-File Report 79-217, 28 p.

Wittenberg, L. A., and McKenzie, S. W., 1978, Hydrologic data in Bear Creek basin and western Jackson County, Oregon, 1976-77: U.S. Geological Survey Open-File Report 78-230, 181 p.

101

WATER-QUALITY CHARACTERISTICS AND CAUSE-EFFECT RELATIONSHIPS

This part of the report provides a background of how water-quality char acteristics are measured, how they interact with one another, and their indi vidual roles in cause-effect relationships.

Discharge

The seasonal streamflow cycle in the Pacific Northwest includes high discharge during periods of high precipitation in winter and low discharge and little precipitation in summer and early fall. Discharge is measured as a volume of water, in cubic feet per second, passing a given point.

The concentration of dissolved solids in natural water varies with streamflow, depending on whether the water in the stream is from surface runoff or from ground-water sources. The chemical quality of streams is also affected by water entering the stream from point or nonpoint sources. If the source inflow is constant, as is often true with point sources, and the dis charge of the stream varies, the effect on the stream will be less at high flows and greater at low flows.

Discharge has a cause-effect relationship with suspended-sediment con centration and temperature. The energy associated with periods of increasing and high stream velocities causes erosion and transport of suspended sediment. (See Brown and others, 1979, for greater detail.) Periods of high flow can also be associated with high turbidity.

Figure 26 shows the medians of mean monthly discharges for Bear Creek at Medford, station 14357500. The 1959-75 line shows the median for 17 mean monthly discharges for each month. The 1976 and 1977 lines are mean monthly discharges. The 1976 values are similar to the 1959-75 values, except for February and March, when Emigrant Reservoir was being filled. As a result of scant precipitation that caused streamflows to be reduced significantly, mean monthly discharges for 1977 were very low except for the months of May and September. Natural streamflow in most of the small tributaries during 1977 was very low or nonexistent. Therefore, the reader should be aware that 1977 samples were collected during atypical climatic and hydrologic conditions.

Temperature

Temperature is an important physical parameter in the aquatic system. Temperature varies over a 24-hour period (diel), seasonally, and with dis charge. Solar radiation is generally the most significant natural source of direct and indirect heat, which results in increased temperature. The energy components affecting stream temperature were discussed in detail by Stevens, Ficke, and Smoot (1975). According to the Federal Water Pollution Control Administration (1967), "Temperature, a catalyst, a depressant, an activator, a restrictor, a stimulator, a controller, a killer, is one of the most import ant and most influential water-quality characteristics to life in water."

105

250

200Q

.-IO OT

°£ rr 150

1 I I I T

< O

311O

100

50

OCT NOV DEC JAN FEB MAR APR MAY JUNE JULY AUG SEPT ANNUAL

Figure 26. Medians of mean monthly discharges for 1959-1975 water years and mean monthly dischargesfor 1976 and 1977 water years.

Physically, temperature partly controls the concentration of DO in the water and the transport and settling characteristics of sediment. Chemically, temperature affects the rate of reaction, dissociation, and corrosion and also affects ionic strength, conductivity, and solubility. Biologically, temper ature limits the species of life found in the water, affects growth and death rates of micro-organisms, and influences the rate of biochemical-oxygen demand (Hines and others, 1977, p. 40; Velz, 1970, p. 146). Many aquatic organisms are called "cold-blooded" because their metabolism and their ability to re produce and survive are directly controlled by the temperature of the water in which they live. For instance, certain salmonid fishes can live and spawn only within a very narrow temperature range. The U.S. Environmental Protection Agency (1976) recommended that maximum weekly average temperatures not exceed 75°F for growth or migration routes of trout arid some salmonids and 55°F for spawning and egg development of salmon and brook trout. Temperature, there fore, is a physical parameter that affects, to a large extent, the beneficial use of water.

The DEQ (1977) has established a standard for allowable temperature in creases in freshwater that reads as follows: "No measurable increases shall be allowed when stream temperatures are 58° F. or greater; or more than 0.5° F. increase due to a single-source discharge when receiving water temperatures are 57.5° F. or less; or more than 2° F. increase due to all sources combined when stream temperatures are 56° F. or less, except for specifically limited duration activities which may be specifically authorized by DEQ under such conditions as it may prescribe and which are necessary to accommodate legit imate uses or activities where temperatures in excess of this standard are unavoidable." Because this standard was established to regulate point sources only, it cannot be used for nonpoint sources in Bear Creek.

106

Suspended Sediment

Suspended sediment is primarily inorganic sand-, silt-, and clay-sized particles; small fragments of organic vegetation; and unattached algae held in suspension mainly by turbulent flow. Suspended sediment is sampled by use of special samplers designed to take depth-integrated, velocity-weighted samples through a vertical column of water. The sampler is lowered into a stream, at a constant rate, to near the bottom and is then raised back to the top. To obtain a representative sample, the procedure is repeated several times in the cross section of the stream (Guy and Norman, 1970).

Erosional processes result in sediment being introduced into the water ways. Areas of erosion include road cuts; plowed fields; barren ground; stream and canal banks; and steep, unstable slopes. Also, landslides and mud- flows can move large quantities of material into waterways. When rains are heavy, overland runoff occurs, which is largely responsible for transporting sediment into the stream. If the velocity is great enough, particles of sand may be brought into suspension along with silt- and clay-sized particles. As velocities decrease, sediment settles out on the stream bottom. Grass and other rooted vegetation tend to reduce the velocity of the water, thus allow ing the suspended particles to settle out.

Sediment can also be deposited in waterways by wind. Particles of soil that are blown from fields without vegetative cover may contribute to the suspended sediment and turbidity of the water.

Pools in streams, as well as ponds, canals, and reservoirs, serve as settling areas for sediment. Large volumes of sediment settle in Reeder Res ervoir during flood periods (Somerville, 1977). Irrigation-supply ponds also allow the sediment to settle out, thus reducing maintenance costs for pumps and sprinkler systems (National Technical Advisory Committee, 1968). The sed iment deposited in reservoirs, ponds, and canals must be removed at times, which results in additional expense for municipalities, farmers, and irri gation districts, and may involve sediment-disposal problems. Sediment also settles on spawning gravels, rendering them unfit for fish spawning, egg hatching, or embryo survival. Suspended sediment is not only a problem in itself, but is a carrier of other material, such as organic chemicals, toxic metals, and bacteria, that adheres to the surface of silt- and clay-sized particles.

Suspended sediment can adversely affect fish and fish-food populations in four ways (European Inland Fisheries Advisory Commission, 1965: "(1) by acting directly on the fish swimming in water in which solids [sediment] are suspended and either killing them or reducing their growth rate, resistance to disease, et cetera; (2) by preventing the successful development of fish eggs and larvae; (3) by modifying natural movements and migrations of fish; and (4) by reducing the abundance of food available to the fish."

DEQ has no established standard for suspended sediment.

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Turbidity

Turbidity is a measure of the light scattered by particulate matter in a sample of water. The Hach_/ turbidimeter, model 2100, that measures the inten sity of light scattered at right angles by the suspended matter, was used in this study. Turbidity values are reported in Jackson Turbidity Units (Jtu). To obtain consistent results, it was necessary to dilute samples until (1) their turbidities were below 40 Jtu's or (2) the calculated turbidities re mained constant upon further dilution. Water that contains very fine sus pended particles generally has more turbidity than does water containing the same weight of coarser suspended sediment. Pickering (1976) reported: "Within certain size and concentration ranges, and with certain types of sus pended material, it is possible to estimate sediment concentration based upon turbidity or optical measurements. However, it is almost impossible to transfer the relationship between sediment concentrations and optical char acteristics from one environment or type of sediment to another."

Turbid waters are not considered to be esthetically pleasing and also reduce the penetration of light needed by aquatic .plants for growth. The National Technical Advisory Committee (1968) recommends that the turbidity in salmon-trout streams should not exceed 10 Jtu. The U.S. Environmental Pro tection Agency (1976) lists the following criterion for freshwater fish and other aquatic life: "Settleable and suspended solids should not reduce the depth of the compensation point for photosynthetic activity by more than 10 percent from the seasonally established norm for aquatic life."

DEQ (1977) has set a standard for turbidity that relates primarily to point sources. It reads as follows: "No more than a 10 percent cumulative increase in natural stream turbidities shall be allowed except for certain specifically limited duration activities which may be specifically authorized by DEQ under such conditions as it may prescribe and which are necessary to accommodate essential dredging, construction, or other legitimate uses or activities where turbidities in excess of this standard are unavoidable."

Specific Conductance and Dissolved Solids

Specific conductance is a measure of the ability of a liquid to carry an electrical charge and is expressed in micromhos per centimeter at 25°C. The concentration of dissolved solids is proportional to specific conductance.

_/ The use of brand names in this report is for identification purposes only and does not imply endorsement by the U.S. Geological Survey.

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The relationship between specific conductance and dissolved solids applicable to the Bear Creek basin is expressed as follows:

DS = 13 + 0.583 SC (6)

where

DS = dissolved solids, in milligrams per liter, andSC = specific conductance, in micromhos per centimeter at 25°C.

The correlation coefficient for this equation is: 0.98. The correlation co efficient here is a measure of the relationship between specific conductance and DS data. A perfect relationship would have a value of +1.00, and 0.00 indicates random data (no relationship). The Bear Creek data used for this equation are in U.S. Geological Survey files.

For a given area under natural conditions, surface water generally has a lower specific-conductance value than does ground water. Specific-conductance levels may vary greatly from stream to stream, but they normally follow a consistent annual pattern on individual streams. Abnormal deviations from this pattern suggest the possibility of discharges high in dissolved solids. Water-quality problems associated with high levels of dissolved solids include the obvious taste and odor problems such as those associated with certain ground water or mineral springs (for example, lithia water in Ashland).

No standards for specific conductance or dissolved solids have been established by DEQ.

Dissolved Oxygen

Dissolved oxygen (DO) in water comes from two sources--the atmosphere and photosynthetic activity of aquatic plants. The solubility of oxygen in water is dependent on temperature, partial pressure of oxygen in the atmos phere, and mineral content of the water. For Bear Creek basin, the lower the temperature and the lower the elevation (higher partial pressure), the higher the concentration of DO at saturation. The rate of solution of oxygen is controlled by (1) the degree of saturation of the water, (2) the temperature of the water, and (3) the amount of water surface in contact with the atmos phere relative to the volume of water.

Photosynthesis is the process by which plants, in the presence of sun light, water, carbon dioxide, and nutrients, grow and produce organic matter while giving off oxygen. When present in large numbers, aquatic plants can be a significant source of DO during daylight hours. A change in DO concen trations can result from oxygen production in photosynthesis and from oxygen consumption in respiration (oxidation of organic material) by both plants and animals. In the dark, only respiration occurs. The amount of oxygen consumed in the dark, added to the oxygen produced in the light, is an estimation of gross photosynthesis. In a stream, diel (24-hour) variations in DO concen trations are common (discussed in detail by Hines and others [1977]).

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DEQ (1977) has established the following DO standards for freshwater in the Rogue River basin: "DO concentrations shall not be less than 80% of saturation at the seasonal low, or less than 95% of saturation in spawning areas during spawning, incubation, hatching, and fry stages of salmonid fishes."

EH

The acidity or alkalinity of a solution may be referred to as pH. Spe cifically, the negative common logarithm of the hydrogen-ion activity is reported as pH. Water with a pH of less than 7 is considered to be acidic, and more than 7 is considered to be basic or alkaline. Most water is near neutral, having a pH value of near 7. Some natural factors that affect the pH of surface water include aquatic biological activity, chemical composition of rocks in the area, ground-water inflow, precipitation, and tributary inflow. Median pH values were used to analyze the data in this report.

In water, carbon dioxide (C02) forms carbonic acid, a weak acid. Any increase in C0£ concentration in water therefore results in a decrease in pH; that is, the water becomes more acidic. Conversely, a decrease in C0£ concen tration in water results in an increase in pH; that is, the water becomes more basic. During photosynthesis, C02 is utilized by plants, and its concentra tion in water is decreased; during respiration C0£ is produced as a metabolic waste product and its concentration is increased. Thus, when photosynthesis is greater than respiration, pH of the water will increase; and when respi ration is greater than photosynthesis, the pH will decrease. The magnitude of the pH change depends on many factors, including the abundance of aquatic plants per unit volume of water, the intensity of sunlight, and availability of nutrients.

Ground-water inflow has an influence on pH in the streams of Bear Creek basin. The alluvium yields water of calcium bicarbonate type. The Roxy and Colestin Formations yield calcium bicarbonate- and sodium bicarbonate-type water (Robison, 1971, 1972). These bicarbonate waters act to buffer the streams and hold the pH values near neutral.

Rapid increases in pH can increase ammonia toxicity to aquatic organisms. Ammonia has been shown to be 10 times as toxic at pH 8.0 as at pH 7.0 (European Inland Fisheries Advisory Commission, 1969).

Bell (1971) performed bioassays with nymphs of caddisflies (two species), stoneflies (four species), dragonflies (two species), and mayflies (one species). Results indicate that caddisflies are the most tolerant to low pH and that mayflies are the least tolerant. The pH values at which only 50 per cent of the organisms emerged ranged from 4.0 to 6.6, with the percentage of emergence increasing with increased pH values above 6.6.

For irrigation use, the pH of water is not normally a critical parameter. Because of the buffering capacity of the soil matrix, the pH of applied water is rapidly changed to approximately that of the soil. To avoid undesirable effects, the pH of irrigation water should not exceed a range of 4.5 to 9.0 (U.S. Environmental Protection Agency, 1976).

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The pH criterion for freshwater aquatic life, as listed by the U.S. Environmental Protection Agency (1976), includes a range of 6.5 to 9.0. The pH State standard, established by DEQ (1977), includes an allowable range of 6.5 to 8.5.

Nitrogen

Nitrogen is an essential component of protein in plants and animals. Nitrite and nitrate are soluble in water, readily available as inorganic forms of nitrogen, and are essential nutrients to plants. Bacteria , by a biochemical process known as nitrification, oxidize ammonia to nitrite and nitrate, con suming DO in the process. Plants convert nitrate to organic nitrogen. Organic nitrogen, found in plants, animals, and surface water, is gradually converted to ammonia by micro-organisms. Sources of nitrogen entering fresh water are the atmospheric fallout, domestic-sewage effluents, animal manure, fertilizer, and agricultural runoff.

Heavy nutrient (nitrogen and phosphorus) concentrations in water commonly result in large numbers of some blue-green and green algae and some diatoms that produce odors and scums. This makes the water less desirable for swim ming, both for esthetic reasons and because some people are allergic to many species of algae. Under certain conditions, several species of blue-green algae produce toxic organic substances that kill fish, birds, and domestic animals. Some of the genera that contain species that may produce toxins are Anabaena, Anacysti s, Aphanizomenon, Coelosphaerium, Cloeotrichia, Nodularia, and Nostoc; some species of Chlorella, a green alga } also are toxic (National Technical Advisory Committee, 1968). Filamentous algae, may interfere with the operation of irrigation systems by clogging ditches, wiers, and screens, thus seriously impeding the flow of water.

High concentrations of nitrate in infant drinking or formula water may cause cyanosis resulting from methemoglobinemia (blue-baby effect). Water containing more than 10 mg/L of nitrate nitrogen should not be used in infant feeding (Brown and others, 1970).

Levels of un-ionized ammonia in the range of 0.20 to 2.0 mg/L have been shown to be toxic to some species of freshwater aquatic life, trout being the most sensitive of the fishes. To provide safety for those life forms not examined, a criterion of one-tenth of the lower value of this toxic-effect range, or 0.02 mg/L of un-ionized ammonia, is suggested (U.S. Environmental Protection Agency, 1976).

Fisheries research has shown that no adverse effects on most warm-water fish should occur when nitrate nitrogen is at or below 90 mg/L or when nitrite nitrogen is at or below 5 mg/L. The research has also shown that no adverse effects on salmonid fish should occur when nitrite nitrogen is at or below 0.06 mg/L. These nitrite and nitrate concentrations are unlikely to occur in natural surface waters (U.S. Environmental Protection Agency, 1976).

The Oregon State Health Division (1976) has set a standard for drinking water not to exceed 10 mg/L of nitrate as N. DEQ has not established standards for nitrogen species in surface water.

Ill

Phosphorus

Phosphorus is prevalent in nature in both inorganic and organic forms. Phosphorus, like nitrogen, is continually being changed by decomposition and synthesis through its role in animal and vegetable metabolism. The concen tration of phosphate in water is limited by the relative insolubility of its salts. Common sources of organic and inorganic phosphorus in water are domestic-sewage effluents, fertilizer, normal decomposition of plants and animals, atmospheric fallout, and, to a limited extent, erosional materials in agricultural runoff (Brown and others, 1970; U.S. Environmental Protection Agency, 1976). High phosphate concentrations occur in winter when low temper atures cause low plant metabolic rates; low phosphate concentrations occur in summer when high temperatures cause high metabolic rates.

Mackenthun (1973) advised that keeping concentrations of total phosphorus below 0.1 mg/L should prevent plant nuisance in streams and other flowing waters. An orthophosphate as P concentration of 0.035 mg/L is reported to be above the concentration of phosphorus measured in some highly productive natural lake waters (Schindler, 1971). Researchers have found the ratio of nitrogen to phosphorus of 16N:1P to be desirable in supporting plant growth. This molar ratio is approximately equal to the N:P ratio found in algal cells (Stumm and Morgan, 1970; Kramer and others, 1972).

No standards have been established by DEQ for phosphate concentrations in streams.

Indicator Bacteria

The presence of indicator bacteria suggests in-water bacterial contami nation originating from excreta of warmblooded animals (including man, domestic and wild animals, and birds). According to the Federal Water Pol lution Control Administration (1969), the ideal bacterial indicator should:

1. Be applicable in all waters and give uniform results.2. Always be present in water with pathogenic (disease-causing)

bacteria and proportional to pathogens.3. Never be present in waters that do not contain pathogens.4. Lend itself to routine quantitative testing without interference.5. Have a greater survival time in water than do pathogens.

The following discussion of specific indicator bacteria indicates their usefulness in evaluating water quality.

Total Coliform Bacteria

Coliform organisms have long been used as indicators of sewage pollution. However, the total coliform group includes bacteria from soil, water, and veg etation, as well as from feces. The total coliform test remains the primary indicator of bacteriological quality for potable water, distribution-system water, and public drinking-water supplies.

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The coliform group is defined as the aerobic and facultative anaerobic, gram-negative, nonspore-forming, rod-shaped bacteria that ferment lactose with gas formation within 48 hours at 35°C. The membrane-filter method defines the total coliform group as all organisms that produce colonies with a golden- green metallic sheen within 24 hours when incubated at 35°C +1°C on M-Endo medium (Greeson and others, 1977).

The U.S. Environmental Protection Agency's (Bordner and Winter, 1978) total coliform criteria for agricultural water is 5,000 coliform per 100 mL. The DEQ currently (1979) uses the total coliform test as its State standard when checking water suspected of containing fecal material.

Fecal Coliform Bacteria

Fecal coliform are bacteria of the coliform group that are present in the gut or feces of warmblooded animals, including man. Within 24 hours, these bacteria will produce gas from lactose in a suitable culture medium at 44.5°C +0.2°C (Greeson and others, 1977). The presence of fecal coliform organisms may indicate recent and possibly dangerous contamination. In using the mem brane test, these organisms will produce blue colonies within 24 hours when incubated at 44.5°C +0.2°C on M-FC medium.

The presence of fecal coliform bacteria should relate to the probable occurrence of waterborne pathogens. Data have been collected showing that when there are more than 200 fecal coliform per 100 mL, Salmonella isolation approaches 100 percent frequency. On the basis of this information, the U.S. Environmental Protection Agency (1976) recommends the following stream

criteria based on a minimum of five samples over a 30-day period: irFecal coliform bacterial level should not exceed a log mean of 200 per ml, nor should more than 10 percent of the total samples taken during any 30-day period exceed 400 per 100 ml."

The U.S. Environmental Protection Agency's (Bordner and Winter, 1978) fecal coliform criteria for agricultural water is 1,000 fecal coliform per 100 mL.

The bacteria standard established by DEQ (1976) for Bear Creek and its tributaries states that average concentrations of "Organisms of the coliform group where associated with fecal sources * * * shall not exceed 1,000 per 100 mis, except during periods of high natural surface runoff." This study has used the membrane-filter fecal coliform test.

Fecal Streptococci Bacteria

The normal habitat of fecal streptococci organisms is the intestine of man and animals. Two additional fecal streptococci biotypes of limited sanitary significance live in the soil, in irrigation water, and in water exposed to temperatures of below 12°C for extended periods (Geldreich, 1970). When using the membrane test, all the above organisms will produce pink or red colonies within 48 hours when incubated at 35°C +1°C on KF agar (Greeson and others, 1977).

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\DEQ has no standards for fecal streptococci bacteria. The Jackson County

Health Department uses the fecal coliform and fecal streptococci standard of less than 200 colonies per 100 mL when evaluating bathing water (John La Riviere, written commun., May 1978).

Use of Indicator Bacteria Data in Irrigation Practices

Bacteriological data are useful in evaluating the types of irrigation commonly practiced. Because sprinkler water is applied directly to fruits and vegetables that may be consumed raw, it requires the best quality of water. Flooding a field with water containing pathogenic organisms may cause micro biological problems if the food is eaten without thorough cooking. Subirri gation and furrow irrigation present fewer problems because the water rarely reaches the upper parts of the plants.

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GLOSSARY OF SELECTED TERMS

[Many definitions were obtained or modified from Greeson and others (1977); Langbein and Iseri (1960); Britton, Averett, and Ferreira (1975); and Rickert and others (1978)]

Alga, algae (n), algal (adj).--Simple plants, many microscopic, containingchlorophyll. Most algae are aquatic and may produce a nuisance when con ditions are suitable for prolific growth and subsequent death and decay.

Aquatic (adj).--Pertaining to water; aquatic organisms such as algae or fish live in water.

Bacteria (n), bacterial (adj).--Microscopic unicellular organisms. Somebacteria cause disease whereas others perform an essential role in the recycling of materials.

Base flow or base runoff (n).--Sustained or fair-weather runoff. Inmost streams, base runoff is composed largely of ground-water effluent.

Beneficial use (n).--A desired use of water or a water body.

Benthos (n), benthic (ad.l).--The community of organisms living in or on the bottom of an aquatic environment.

Best management practice (n).--A land-management practice or combination of practices determined to be practicable and most effective in preventing or reducing nonpoint-source problems to a level compatible with water- quality goals.

Biochemical oxygen demand (BOD) (n).--The quantity of dissolved oxygen, inmilligrams per liter, used for the decomposition of carbonaceous organic material by micro-organisms, such as bacteria. A value may be for 5 days or an ultimate demand.

Blue-green algae (n).--A group of algae with a blue pigment in addition togreen chlorophyll. Members of this group often cause nuisance conditions in water.

Community (n).--Any naturally occurring group of different organisms inhabit ing a common environment and interacting with one another through food relationships.

Concentrator (n).--A land and(or) water activity that causes the concentration of a constituent at the outfall to exceed that at the inflow. This often occurs during irrigation when water is consumed through evapotranspiration.

Detention time (n).--Period of time for a unit of water to flow through a specified reach of stream.

Diatom (n).--A unicellular or colonial alga having a siliceous shell.

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\Diel (adj).--Relating to a 24-hour period that generally includes a day and

the adjoining night.

Diluter (n).--A land and (or) water activity that causes the concentration of a constituent at the outfall to be less than that at the inflow. An example is a pasture filtering out suspended material from irrigation water.

Discharge (n, adj).--A volume of water passing a given point in a specified period of time, in cubic feet per second.

Dissolved oxygen (DO) (n).--The oxygen dissolved in water, waste water, orother liquid, generally expressed in milligrams per liter or percent of saturation.

Facultative (adj).--Able to live and grow under more than one set of con ditions. Facultative bacteria can live in aerobic and anaerobic con ditions. Facultative benthic invertebrates can live in areas with or without organic enrichment.

Fecal coliform bacteria (n).--That part of the coliform group that is present in the gut or the feces of warmblooded animals, including man; they are indicators of possible sewage contamination. They are formally char acterized as gram-negative, non-spore-forming, rod-shaped bacteria which produce blue colonies within 24 hours when incubated at 44.5°C +0.2°C on M-FC medium.

Fecal streptococcal bacteria (n).--A particular group of bacteria found in the gut of warmblooded animals, including man; their presence in natural waters is considered to verify fecal contamination. They are formally characterized as gram-positive, cocci bacteria which produce red or pink colonies within 48 hours when incubated at 35°C + 1°C on KF agar.

Genus, genera (n).--The taxonomic category below family, consisting of species; the first part of the scientific name of organisms.

Green algae (n).--Algae that have pigments similar in color to those of higher green plants. Some forms produce algal mats or floating "moss" on lakes.

Ground-water runoff (n).--That part of the runoff that has passed into the ground, has become ground water, and has been discharged into a stream channel as spring or seepage water.

Invertebrate (n).--An animal without a backbone. Common aquatic examples are larva and pupa stages of insects.

Irrigation return flow (n).--That part of irrigation water that is not con sumed by evapotranspiration and that returns to its source or another body of water.

Jackson turbidity unit (Jtu) (n).--A unit of turbidity using the Jackson candle turbidimeter.

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Larva, larvae (n).--An active, immature stage of an animal during which its body form differs from that of the adult.

Loading (n).--The amount of a given substance or type of material discharged or otherwise entering a water body in a given unit of time.

Median (n).--The middle number in a given sequence of numbers, taken as the average of the two middle numbers when the sequence has an even number of numbers.

Nitrification (n).--The biological formation of nitrite or nitrate from com pounds containing reduced nitrogen.

Nonpoint source (n).- A stream or water body affected by the introduction of material from (1) diffuse sources of land runoff, or (2) an alteration of banks and adjacent areas along a stream corridor or other water bodies. This includes irrigation-return flows.

Nutrient (n).--Any chemical element, ion, or compound that is required by an organism for the continuation of growth, for reproduction, and for the life processes.

Nymph (n).--An immature stage of an insect that resembles the adult stage in body form.

Organic (n).--Pertaining or relating to a compound containing carbon.

Organisms (n).--Any living entity.

Overland flow (n).--The flow of rainwater or snowmelt over the land surface toward stream channels.

Pathogen (n), pathogenic (adj).--A disease-causing organism.

Periphyton (n).--The community of micro-organisms that are attached to or live upon submerged surfaces.

pH (n).--The reciprocal of the logarithm of the hydrogen-ion concentration.The pH value of water is a measure of the degree of its acid or alkaline reaction.

Photosynthesis (n).--The process by which simple sugars and starches are pro duced from carbon dioxide and water by living cells, with the aid of chlorophyll and in the presence of light. In the process, carbon dioxide is consumed and oxygen is released.

Phytoplankton (n).--The plant part of the plankton.

Plankton (n).--The community of suspended or floating organisms that drifts passively with water currents. The organisms are mostly microscopic and include both plants and animals.

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\Point source (n).--Any discernible confined and discrete conveyance includ

ing, but not limited to, any pipe, ditch, channel, or container from which material is or may be discharged.

Respiration (n).--A life process in which carbon compounds are oxidized to carbon dioxide and water.

Sample (n).--A small separate part of something that is representative of the whole.

Source (n).--A land and (or) water activity that causes the load (weight per time) of a constituent at the outflow to exceed that at the inflow. An example is erosion during irrigation.

Sink (n).--A land and (or) water activity that causes the load (weight pertime) of a constituent at the outflow to be less than that at the inflow. An example is the use of a pond to remove suspended sediment.

Species (n, sing and pi).--The basic unit for the classification of organisms; the taxonomic category below genus, and the second part of the scientific name of an organism.

Substrate (n).--The physical surface upon which something lives.

Suspended sediment (n).--Fragmental material, both mineral and organic, that is maintained in suspension in water.

Turbidity (n), turbid (adj).--The ability of materials suspended in water to reduce the penetration of light.

Water-quality problem (n).--When (1) kinds and amounts of matter dissolved or suspended in natural waters, and (2) the physical characteristics of the waters result in an impairment of the suitability of waters for any of the beneficial uses, actual or potential; for example, the aquatic en vironment is altered so that wildlife, fish, and other aquatic life are adversely affected.

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Water Quality of Bear Creek Basin, Jackson County, Oregon · 2010-11-26 · Water Quality of Bear Creek Basin, Jackson County, Oregon By Loren A. Wittenberg and Stuart W. McKenzie