Salt and Selenium in Grand Valley Rivers and Streams

Joshua LinardU.S. Geological Survey Hydrologist

jilinard@usgs.gov

Presentation Outline

• Importance of salt and selenium• Environmental processes controlling the movement

of salt and selenium• Water-quality standards for salt and selenium• Salt and selenium in the Colorado River• Salt and selenium in Grand Valley tributaries• Concentration vs. load• Control initiatives• Current investigations

What are Salt and Selenium?

• Salt– Total Dissolved Solids: the mass of all cations and

anions in an aqueous solution• Selenium

– A naturally occurring trace element• It’s essential to life, but in excess can be harmful

Why Study Salt and Selenium?• High salinity water

– Clogs and corrodes household pipes and fixtures– Limits agricultural productivity

• High selenium in water– Limits reproductive ability and can even be fatal to biological

organisms– Colorado Pike Minnow, Razor Back Sucker, Boney Tail Chub, Hump

Back Chub

Spatial Distribution of Mancos Shale

Environmental Processes

Sources of Water

• Average annual precipitation: 8 in/yr• Canals• Irrigation: 11-70 in/yr

– Residential areas– Agricultural areas

Concentration vs Load• Seasonality in salt and selenium are, generally,

explored in units of …– Concentration

• Units of mass/volume

– Load• Units of mass/time

– Salinity: tons/day– Selenium: lbs/day

Water-Quality Standards• Standards focus on concentrations• Colorado Department of Health and Environment

– Salinity• Established in 1976 for the entire Colorado River Basin• Flow-weighted annual values shouldn’t exceed 723 mg/l (ppm) below

Hoover Dam

– Selenium• The water-quality standards are the 85th percentile for the

most recent 5 year period– If 100 samples are available, 85 must be below the standard

• Established in 2000• Acute = 18.4 μg/l (ppb)• Chronic = 4.6 μg/l (ppb)

Water-Quality Standards for Salinity and the Grand Valley

• Salinity standard at Hoover Dam: 723 mg/L

Stream Gage Mean-Daily Salinity Concentration (mg/L)

Colorado River near Cameo, CO 368

Gunnison River near Grand Junction, CO 786

Colorado River near Colorado-Utah State Line 604

Persigo Wash at River Road 2,063

Water-Quality Standards for Selenium and the Grand Valley

• CDPHE chronic standard for selenium: 4.6 μg/L

Stream Gage Mean-Daily Selenium Concentration (μg/L)

Colorado River near Cameo, CO 0.6

Gunnison River near Grand Junction, CO 4.5

Colorado River near Colorado-Utah State Line 4.0

Persigo Wash at River Road 35.5

Why are concentrations so much higher in tributaries than in the Colorado River?

• Seasonal changes in the availability of water effect the amount of salt and selenium in streams– The Colorado River has more water to dilute

tributary inputs of salt and selenium– Tributary water has more interaction with the

Mancos Shale in the Grand Valley

Leib, K.J. 2008. Concentrations and Loads of Selenium in Selected Tributaries to the Colorado River in the Grand Valley, Western Colorado, 2004-2006. U.S. Geological Survey Scientific Investigations Report 2008-5036.

Concentration and Load vs Streamflow

• Relationships to streamflow are general• At a particular point, as flow increases the load

increases and concentration decreases

• Vary between salt and selenium• Vary from place to place

Concentration and Load vs Streamflow

Concentrations and Loads of Salt and Selenium Measured at the Colorado River near Colorado-

Utah State Line

Concentrations and Loads of Salt and Selenium Measured at Persigo Wash at River Road

Salt and Selenium Control

• Management options– Increase flow to dilute salt and selenium

• Not really an option in the arid environment

– Decrease load to lower concentrations• Control initiatives are aimed at minimizing loads

– Minimize source loads– Decreases tributary loads– Decreases concentrations in the Colorado River

Methods to Control Salt and Selenium

• Irrigation delivery system improvements– Lining and piping of canals and laterals

• Irrigation system improvements– Sprinklers, drips, micro, etc.

• Best Management Practices for residential areas• Line Ponds• Indirect effects from land-use change and

population growth

Effects of Land-use Change on Source Loads

1. Quantify irrigation water use and deep percolation in representative areas where agricultural land has been converted to suburban use.

2. Compare irrigation water use and deep percolation at similar agricultural and suburban sites in the Grand Valley.

3. Quantify deep percolation from pond seepage for a selected number of ponds.

From Mayo, J.W. 2008. Estimating the effects of conversion of agricultural land to urban land on deep percolation of irrigation water in the Grand Valley, Western Colorado. U.S. Geological Survey Scientific Investigations Report 2008-5086.

22

Grand Valley Sites

Ponds

Weather Stations

Homes & Fields

Explanation

• 14 Homes

• 4 Gated-Pipe Fields

• 3 Ponds

• 2 CSU Weather Stations

• Monitored for 2 irrigation seasons (2005 & 2006)

23

Typical Residential Sites

5-Acre Estate - bluegrass

¼-Acre Subdivision - bluegrass

5-Acre Estate - Native Plants

5-Acre Estate – Orchard Grass

24

Typical Gated Pipe Sites

CSU – orchard grass

Quail Run – orchard grass

25

Typical Pond Sites

Paradise Hills Pond

Chipeta Pines Pond

26

Irrigation Water Use and Deep Percolation(average acre-feet of water per acre for irrigation season)

1 Acreage for ¼ acre subdivisions in study was 40 percent irrigated on average

2 Acreage for 5 acre estates in study was 32 percent irrigated on average

3 Acreage for gated-pipe and alfalfa sites was assumed to be 90 percent irrigated

4 Acreage for irrigation holding ponds was assumed to be 100 percent covered with water

5 Numbers in parentheses are the range of values

Subdivision Lots

(bluegrass) 1

n=10

5 Acre

Estates

(bluegrass) 2

n=7

5 Acre Estates(native, orchard grass) 2

n=3

Gated Pipe Fields (orchard grass) 3

n=4

NRCS

Alfalfa

Sites 3 n=67

Irrigation Holding Ponds 4

n=4

Irrigation Water Use

(ac-ft/ac)

1.1(0.8 – 1.2)5

0.9 (0.8 – 1.3)

0.3(0.1 – 0.9)

1.5(0.6 – 2.7)

3.8(1.6 – 5.8)

n/a

Deep Percolation

(ac-ft/ac)

0.14(0.00 – 0.42)

0.08(0.01 – 0.17)

0.0(0.0 – 0.04)

0.6(0.0 – 1.5)

1.27(0.0 – 3.3)

9.55(8.2 – 11.8)

27

Salt Loading(tons per acre per year)

• NRCS salt-loading factor for the Grand Valley is 4.1 tons per acre-foot of water applied, with an estimated 50 percent of the load reaching the Colorado River.

Subdivision Lots

(bluegrass)

n=10

5 Acre Estates

(bluegrass)

n=7

5 Acre Estates(native,

orchard grass)

n=3

Gated Pipe Fields

(orchard grass)

n=4

NRCS

Alfalfa Sitesn=67

Irrigation Holding Ponds

n=4

0.28 0.17 0.0 1.37 2.89 19.6

Can we see the effects of their implementation in the water-quality of the streams?

Stream Gage 1986-2003

Colorado River near Cameo, CO -193,000

Gunnison River near Grand Junction, CO -202,000

Colorado River near Colorado-Utah State Line -322,000

From 1986 to 2003 the salinity load measured at the Colorado-Utah Stateline has decreased by over 300,000 tons.

Butler, D.L., 1996, Trend analysis of selected water-quality data associated with salinity-control projects in the Grand Valley, in the Lower Gunnison River Basin, and at Meeker Dome, Western Colorado: U.S. Geological Survey Water-Resources Investigations Report 95-4274, 38 p.

Bauch, N.J., and Spahr, N.E., 1998, Salinity Trends in Surface Waters of the Upper Colorado River Basin, Colorado: Journal of Environmental Quality, v. 27, no. 3, p. 640-655.

Leib, K.J. and Bauch, N.J., 2007, Salinity trends in the Upper Colorado River Basin upstream from the Grand Valley Salinity Control Unit, Colorado, 1986-2003, U.S. Geological Survey Scientific Investigations Report 2007-5288.

Summary

• Underlying geology is the source of salt and selenium– Ground water transports salt and selenium to the

rivers and streams in the Grand Valley• Water-quality at the Colorado-Utah State Line meets

standards• Concentrations and Loads vary

– Seasonally– Between salt and selenium– Place to place

Summary• Minimizing source loads in tributaries of the Grand

Valley, minimizes concentrations in the Colorado River• Controlling sources of salt and selenium

– Irrigation practices– Best management practices– Land-use

• Conversion from previously irrigated land to residential reduces source loading

• Long-term trends indicate control initiatives are working

Websites:http://co.water.usgs.gov/index.html

http://waterdata.usgs.gov/co/nwis/rt/

http://rmgsc.cr.usgs.gov/cwqdr/Piceance/index.shtml

http://wdr.water.usgs.gov/nwisgmap/