Technical Memorandum - VBgov.com

Technical Memorandum

301 Bendix Road, Suite 400

Virginia Beach, VA 23452

T: 757.518.2400

F: 757.518.2401

Prepared for: The City of Virginia Beach Department of Public Works

Project title: Lake James Water Quality Monitoring and Evaluation

Project no.: 150929.002


Subject: 2017 Water Quality Monitoring of Lake James and Nearby Waters

Date: April 20, 2018

To: Tara Gallagher, City of Virginia Beach

From: Clifton Bell and Kristina Kowalski

Copy to: Melanie Coffey, City of Virginia Beach

2017 Water Quality Monitoring of Lake James and Nearby Waters

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WO25 T1 Final Lake James WQ Eval_04-20-2018

Table of Contents

Executive Summary .................................................................................................................................................. 1

Section 1: Introduction ............................................................................................................................................. 2

1.1 Description of Study Area ............................................................................................................................... 2

1.2 Summary of Previous Monitoring ................................................................................................................... 3

Section 2: Methods .................................................................................................................................................. 4

2.1 Sampling Locations ......................................................................................................................................... 4

2.2 Sampling Dates and Conditions ..................................................................................................................... 5

2.3 Field Methods .................................................................................................................................................. 6

2.4 Laboratory Methods ........................................................................................................................................ 6

Section 3: Results..................................................................................................................................................... 7

3.1 Field Parameters ............................................................................................................................................. 7

3.1.1 Lake Profiles ...................................................................................................................................... 7

3.1.2 Spatial Patterns ............................................................................................................................... 10

3.2 Nitrogen ......................................................................................................................................................... 19

3.3 Phosphorus .................................................................................................................................................... 24

3.4 Total Suspended Solids ................................................................................................................................ 26

3.5 Chlorophyll-a and Algae................................................................................................................................. 27

Section 4: Discussion ............................................................................................................................................. 29

4.1 General Factors Affecting Cyanobacterial Blooms ...................................................................................... 29

4.2 Potential Nutrient Limitations in Lake James .............................................................................................. 30

4.3 Conceptual Model of Lake James ................................................................................................................ 31

Section 5: Conclusions and Recommendations ................................................................................................... 33

References .............................................................................................................................................................. 35

Attachment A: Water Quality Monitoring Data ..................................................................................................... A-1

Attachment B: Technical Memorandum on May 2017 Sampling ...................................................................... B-1


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List of Figures

Figure 1. Map of sampling locations for dry and wet weather events .................................................................. 5

Figure 2. Graph of temperature profile in Lake James (Sites 2 and 3) and Lake Christopher (Site 7) .............. 8

Figure 3. Graph of pH profile in Lake James (Sites 2 and 3) and Lake Christopher (Site 7) .............................. 8

Figure 4. Graph of specific conductance profile in Lake James (Sites 2 and 3) and Lake Christopher (Site 7) 9

Figure 5. Graph of dissolved oxygen profile in Lake James (Sites 2 and 3) and Lake Christopher (Site 7) ..... 10

Figure 6. Map of spatial patterns of temperature in Cedar Hill Canal during the probe-based survey

(11/6/2017) .................................................................................................................................................... 11

Figure 7. Longitudinal profile of temperature in Cedar Hill Canal from upstream to downstream during the

probe-based survey (11/6/2017) .................................................................................................................. 12

Figure 8. Graph of temperature at sample sites during the synoptic sampling events of (September–

November 2017). Mid-lake sites (2, 3, and 7) were only sampled during dry weather events. HRRC (site

8) was only actively pumping during one of the four sample events. .......................................................... 12

Figure 9. Map of spatial patterns of pH in Cedar Hill Canal during the probe-based survey (11/6/2017) ..... 13

Figure 10. Longitudinal pattern of pH in Cedar Hill Canal from upstream to downstream during the probe-

based survey (11/6/2017) ............................................................................................................................. 14

Figure 11. Graph of pH at sample sites during the synoptic sampling events (September–November 2017).

Mid-lake sites (2, 3, and 7) were only sampled during dry weather events. HRRC (site 8) was only actively

pumping during one of the four sample events. ............................................................................................ 14

Figure 12. Map of spatial patterns of specific conductance in Cedar Hill Canal during the probe-based survey

(11/6/ 2017) ................................................................................................................................................... 15

Figure 13. Longitudinal profile of specific conductance in Cedar Hill Canal from upstream to downstream

during the probe-based survey (11/6/2017) ................................................................................................ 16

Figure 14. Graph of specific conductance at sample sites during the synoptic sampling events (September–



Figure 15. Map of spatial patterns of dissolved oxygen in Cedar Hill Canal during the probe-based survey

(11/6/2017) .................................................................................................................................................... 17

Figure 16. Longitudinal profile of dissolved oxygen in Cedar Hill Canal from upstream to downstream during

the probe-based survey (11/6/2017) ............................................................................................................ 18

Figure 17. Graph of dissolved oxygen at sample sites during the synoptic sampling events (September–



Figure 18. Graph of ammonia concentrations in Cedar Hill Canal during the probe-based survey

(11/6/2017) .................................................................................................................................................... 20

Figure 19. Graph of ammonia-N concentrations in Cedar Hill Canal from upstream to downstream during the

probe-based survey (11/6/2017) .................................................................................................................. 21

Figure 20. Graph of ammonia concentrations in study sites during the synoptic sampling events

(September–November 2017). Mid-lake sites (2, 3, and 7) were only sampled during dry weather events.

HRRC (site 8) was only actively pumping during one of the four sample events. ....................................... 21


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Figure 21. Graph of nitrate and nitrite concentrations in study sites during the synoptic sampling events



Figure 22. Graph of total Kjeldahl nitrogen concentrations in study sites during the synoptic sampling events



Figure 23. Graph of total phosphorus concentrations in study sites during the synoptic sampling events



Figure 24. Graph of orthophosphate concentrations in study sites during the synoptic sampling events



Figure 25. Graph of total suspended solids concentrations in study sites during the synoptic sampling events



Figure 26. Graph of corrected chlorophyll-a during the dry weather sampling events (September–November

2017) ................................................................................................................................................................ 28

List of Tables

Table 1. Sampling Dates and Site Conditions ........................................................................................................ 5

Table 2. Laboratory Analysis Methods .................................................................................................................... 7

Table 4. Total Algal Biomass (mg/L) in Lake James and Lake Christopher ....................................................... 27

Table 5. Cyanobacteria Density (cells/mL) in Lake James and Lake Christopher ............................................. 28

Table 6. Cyanotoxin Concentrations (ug/L) in Lake James and Lake Christopher ............................................ 29

Table 7. Dissolved Inorganic Nitrogen: Orthophosphate Molar Ratios from Synoptic Sampling Events .......... 31

Table A1-1. Raw Data Measured at Shore Adjacent Sites .................................................................................. A-3

Table A1-2. Raw Data Measured at In-Lake Sites ............................................................................................... A-5

Table A1-3. Results from HRSD Lab: Nutrient and Sediment .......................................................................... A-11

Table A1-4. Results from GreenWater Lab: Algal Properties and Cyanotoxins ............................................... A-17

Table A1-5. Results from GreenWater Lab: Cyanobacteria Composition ........................................................ A-19


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List of Abbreviations

µg microgram(s)

°C degree(s) Celsius

BC Brown and Caldwell

City City of Virginia Beach

cm centimeter(s)

DEQ (Virginia) Department of Environmental Quality

DI deionized

DO dissolved oxygen

EPA U.S. Environmental Protection Agency

ft foot/feet

GWL GreenWater Laboratory

HRRC Hampton Roads Recovery Center

HRSD Hampton Roads Sanitation District

ID identifier

L liter(s)

LF landfill

mg milligram(s)

mL milliliter(s)

mS millisiemens

N nitrogen

ng nanogram(s)

P phosphorus

s.u. standard unit(s)

TKN total Kjeldahl nitrogen

TM technical memorandum

TSS total suspended solids

VDH Virginia Department of Health

WHO World Health Organization


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Executive Summary Lake James is a ~94-acre water body between Indian River Road and Centerville Turnpike in Virginia Beach

that is subject to periodic cyanobacteria blooms. Prior studies have indicated that Lake James had elevated

nutrient and algal levels, and concluded that pumping from the former E.V. Williams borrow pit (now called

the Hampton Roads Recovery Center [HRRC]) to the Cedar Hill Canal may be a pollutant source. This tech-

nical memorandum (TM) presents methods and results of water quality monitoring performed on Lake

James and nearby waters in 2017, performed to interpret potential causes of algal blooms in the lake, and

to provide insight into potential management actions.

The 2017 sampling study involved water quality sampling in Lake James and the Cedar Hill Canal under both

dry and wet weather conditions, and under both summer and fall conditions. Samples were analyzed for vari-

ous water quality constituents including nutrients, chlorophyll-a, algal type, and algal toxins. A special field

study was conducted in November 2017 to map ammonia-nitrogen (ammonia-N) concentrations in the Ce-

dar Hill Canal at a detailed spatial resolution. Samples were also collected from nearby Lake Christopher,

which serves as a reference lake because it has characteristics similar to Lake James, but is not affected by

the canal overflows.

Major findings of the 2017 sampling study are as follows:

1. Lake James had relatively favorable water quality conditions during the 2017 sampling events. During

the 2017 sampling events, algal and nutrient concentrations were relatively low, and nutrient concentra-

tions were comparable with those in Lake Christopher. Although cyanobacteria were present in Lake

James at higher densities than in Lake Christopher, cyanotoxins were not detected above advisory

thresholds. The sampling results reveal that Lake James can experience relatively good water quality

under the observed conditions. However, higher nutrient concentrations or algal levels would be ex-

pected when the canal is, or has recently been, directly discharging to the lake, or when other conditions

(e.g., seasonal lake turnover) make higher levels of nutrients available to algae at the surface.

2. The Cedar Hill Canal was confirmed to have elevated concentrations of nutrients derived from HRRC.

The 2017 water quality monitoring evaluation generally confirmed previous findings that the Cedar Hill

Canal experiences elevated concentrations of several constituents—most notably ammonia-N—derived

primarily from the HRRC discharge.

3. Lake James can experience either phosphorus- or nitrogen-limiting conditions for algal growth. An eval-

uation of nitrogen (N)-to-phosphorus (P) ratios revealed that Lake James can experience either phospho-

rus or nitrogen limitation at different times. Under nitrogen-limiting conditions, the lake would be more

sensitive to ammonia inputs from the Cedar Hill Canal or watershed. The mixed or alternating limitation

may explain why different cyanobacteria taxa—including nitrogen fixers and non-nitrogen fixers—are dom-

inant during different bloom events.

4. Lake James has characteristics unrelated to the canal inputs that probably favor periodic cyanobacte-

ria blooms. Lake James’ long retention time, stratification/turnover cycles, and developed watershed

make it prone to sustain a moderate cyanobacteria biomass regardless of the canal water quality. This is

evident by the fact that Lake Christopher also had moderate densities of cyanobacteria. However, it is

reasonable to conclude that the nutrient inputs from the canal may be capable of triggering and sustain-

ing larger blooms in Lake James that would otherwise not occur. The recent pattern of cool weather

blooms may also be favored by lake turnover and the presence of cyanobacteria taxa with a wide range

of temperature tolerance.


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The following are specific recommendations that could limit the adverse effects of cyanobacteria blooms in

Lake James:

1. Implement best management practices in direct discharge areas. Reduction of nutrient loading is often

the most effective way to reduce both the frequency and magnitude of cyanobacteria blooms. It could be

recommended that residents of the watershed continue to reduce nutrient loads from suburban

sources. Such measures include avoidance of lawn fertilization near the lake, collection of pet waste,

keeping yard waste out of streets, and prevention of irrigation runoff.

2. Divert the HRRC discharge from the Cedar Hill Canal, or reduce its nutrient content. Based on 2017

sampling results, the HRRC discharge is the primary source of nutrients in the Cedar Hill Canal. This dis-

charge appears to be complying with its effluent permit limits and was not observed to cause exceed-

ances of Virginia’s water quality criterion for ammonia. Given the importance of Lake James for storm-

water management and downstream flood control, it is probably more feasible to improve the quality of

the HRRC discharge than to disconnect the canal from Lake James under all hydrologic conditions. The

City is currently evaluating the feasibility of diverting the HRRC discharge away from the Cedar Hill Canal.

In addition, HRRC is expected to stop dewatering its pit in 5 to 7 years, after which the quality of the dis-

charge to the Cedar Hill Canal is expected to be significantly improved.

3. Conduct algacide treatments as needed. Although prevention of algae blooms is a preferred technique,

Lake James may experience periodic cyanobacteria blooms even after the canal water quality is im-

proved. For this reason, occasional algacide treatments may continue to be necessary.

4. Perform artificial mixing or aeration. These in-lake management techniques are sometimes effective for

reducing cyanobacterial blooms. However, they have a mixed record of success, and some of the fail-

ures can be attributed to undersizing the systems. If this option were pursued for Lake James, it would

be recommended to carefully consider Lake James’ specific characteristics. Larger systems are more

likely to be effective but also have higher capital and operational costs.

Section 1: Introduction This TM presents methods and results of water quality monitoring performed on Lake James and nearby wa-

ters in 2017. The monitoring was performed to improve the City of Virginia Beach’s (City’s) understanding of

the spatial, seasonal, and hydrologic variability in water quality of Lake James and the Cedar Hill Canal. This

information can be used to interpret potential causes of algal blooms in the lake, and to provide insight into

potential management actions.

1.1 Description of Study Area

Lake James is a ~94-acre water body between Indian River Road and Centerville Turnpike in Virginia Beach

(Figure 1). Originally created as a borrow pit for the construction of Interstate 64, the lake is currently used

for stormwater management and is also valued as a neighborhood amenity. The surrounding community in-

cludes more than 270 homes, over 100 of which are on the lakefront. The maximum lake depth is approxi-

mately 40 feet (Bass and Schafran 2009). Although residents sometimes use the lake for boating, gas mo-

tors are not allowed on the lake. The City does not recommend swimming in stormwater management

features, including Lake James.

Lake James receives drainage from the surrounding residential lands, the Kemps River Crossing Shopping

Center, and the Cedar Hill Canal. The lake is connected to the canal by two short channels on the western

side of the lake. Although these connecting channels have weir structures, flow from the canal to the lake

can occur when the weirs are overtopped during wet weather events. Under other hydrologic conditions,


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Lake James discharges to the canal via these same connecting channels. Lake James receives an undeter-

mined amount of direct groundwater discharge. The Cedar Hill Canal discharges to the eastern branch of the

Elizabeth River about 2 miles north of Lake James. The Hampton Road Recovery Center (HRRC) is permitted

to discharge flow from its pit dewatering operation to the canal upstream of Lake James.

Lake James is subject to periodic algal blooms. According to anecdotal reports from residents, the lake’s al-

gal levels increased during the years leading up to 2009, prompting the homeowners to sponsor a monitor-

ing study (Bass and Schafran 2009). This prior study indicated that Lake James had higher nutrient and

chlorophyll-a concentrations than nearby Lake Christopher, and concluded that pumping from the former

E.V. Williams borrow pit to the Cedar Hill Canal may be a pollutant source. More recently, cyanobacterial

blooms in January and February 2017 and January 2018 caused visible algal scums on the surface, prompt-

ing algacide treatments. In summer 2017, the City engaged Brown and Caldwell (BC) to perform a water

quality monitoring study of Lake James and the Cedar Hill Canal. The results are intended to support inter-

pretations of pollutant sources, causes, and potential mitigative measures for algal blooms on Lake James.

1.2 Summary of Previous Monitoring

The monitoring by Bass and Schafran indicated that several water quality parameters were elevated in Lake

James compared to Lake Christopher, which is also a man-made lake and is considered a comparable lake

without the influence of the Cedar Hill Canal (Bass and Schafran 2009). For example, specific conductance

in Lake James was as reported in the 0.6–1.1 millisiemens per centimeter (mS/cm) range in Lake James,

compared with 0.3–0.4 mS/cm in Lake Christopher. Similarly, inorganic nitrogen (N) (ammonia plus nitrate)

concentrations were reported as approaching the 2-milligram per liter (mg/L) range in Lake James but less

than 1 mg/L in Lake Christopher. This study also indicated that these constituents were elevated in the Ce-

dar Hill Canal and E.V. Williams borrow pit discharge. For example, inorganic nitrogen (ammonia plus nitrate)

concentrations were 3 to 8 mg/L in the canal, and exceeded 30 mg/L in some groundwater seeps from the

borrow pit wall. Total phosphorus (P) was also elevated (> 2mg/L) in the groundwater seepage, although the

difference in phosphorus concentrations between Lake James and Lake Christopher was not as significant

as that for the nitrogen species.

Malcolm Pirnie performed an investigation of water quality of the Cedar Hill Canal on behalf of the City of Vir-

ginia Beach (Malcolm Pirnie 2009). This investigation confirmed elevated ammonia concentrations in the

canal and groundwater being pumped from the E.V. Williams borrow pit. However, the study report indicated

that Virginia water quality criteria for ammonia was not exceeded, and found no potential public health risk

associated with the borrow pit discharge. A suite of potential solid waste constituents, including dissolved

metals and volatile organic compounds, were determined to be at similar levels in Lake James and Lake

Christopher. Malcolm Pirnie concluded that nitrogen from the canal was not a major factor for algal growth in

Lake James, and that cyanobacteria proliferation was attributable to other lake characteristics (Malcolm

Pirnie 2009).

Solitude Lake Management performed water quality sampling in Lake James in June 2013 on behalf of the

Lake James Homeowners Association. Ammonia concentrations were less than 0.1 mg/L in the lake but

about 3 mg/L in the canal. Similarly, total phosphorus concentrations were 0.06 mg/L or less in the lake but

about 0.20 mg/L in the canal. Solitude concluded that the canal was the primary source of phosphorus en-

tering the lake.

The Virginia Department of Environmental Quality (DEQ) sampled Lake James during the cyanobacterial

bloom of February 2017. Results revealed high densities of a potential cyanotoxin former, Aphanizomenon

flos-aquae, and low densities of another potential toxin-former, Planktothrix isothrix. Cyanotoxins were not

being monitored during this sampling event. In contrast, DEQ samples of the January 2018 bloom showed

that it was dominated by Planktothrix species at a density of 8,225,400 cells per milliliter (mL). During this


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event, the cyanotoxin microcystin was detected at concentrations greater than 20 micrograms per liter

(µg/L), which exceeded the Virginia Department of Health’s (VDH’s) advisory threshold (6 µg/L).

On behalf of the City of Virginia Beach Department of Public Works, BC sampled water quality at seven loca-

tions on Lake James and the Cedar Hill Canal in May 2017. These sampling results confirm elevated meas-

urements of several water quality parameters in the Cedar Hill Canal, most notably specific conductance

(0.8–2.1 mS/cm) and ammonia-N (0.4–5.0 mg/L). These parameters were significantly lower in Lake James

than in the canal; for example, specific conductance in the lake was about 0.3 mS/cm, and ammonia-N was

0.03–0.10 mg/L. The bioavailable form of phosphorus (orthophosphorus) was relatively low (0.01–0.02

mg/L) in both the canal and the lake. Attachment B provides more information on this sampling effort.

Lake water samples from the May 2017 BC sampling event were analyzed for several cyanotoxins and cya-

nobacterial species composition. The cyanotoxin cylindrospermopsin was detected at a level lower than the

U.S. Environmental Protection Agency’s (EPA’s) draft recreational contact guideline. The cyanotoxin microcys-

tin-LR was detected at 4.7 µg/L, which was below but close to VDH’s advisory threshold (6 µg/L). The cyano-

bacteria presently included moderate densities of the same two potential toxin formers detected by DEQ in

March 2017: Aphanizomenon flos-aquae and Planktothrix agardhii. Full results of the May 2017 sampling

event are included in Attachment B to this TM.

Section 2: Methods The City retained BC in 2017 to conduct additional monitoring and to perform four field sampling events be-

tween August and December 2017. Two of these events were conducted during dry weather conditions, and

the other two were conducted during wet weather conditions (≥ 0.1 inch of rainfall). One wet and one dry

event were captured in September (henceforth referred to as the warm month samples) as well as October

and November (cooler months). In addition, in November 2017, a probe-based water quality survey was per-

formed on the Cedar Hill Canal and Lake James. This section describes the methodology of water quality

sampling collection and the canal survey.

2.1 Sampling Locations

Under dry weather conditions, water quality samples were collected at nine sampling locations (Figure 1).

Wet weather sampling was performed at the same sites excluding sites within Lake James (Sites 2 and 3)

and Lake Christopher (Site 7). Sites 1 and 6 are located on the Lake James side of the northern and south-

ern weir, respectively. Site 4 is located in the Cedar Hill Canal at the outfall that drains the HRRC. This sam-

ple is intended to analyze the quality of water in the canal near the HRRC discharge site. HRRC pumps

groundwater into a small onsite retention pond, which drains to Site 4. If HRRC was pumping during sam-

pling events, the field crew sampled the pumped water at Site 8. This occurred once during the wet weather

event conducted on September 14, 2017. Site 5 is located in the Cedar Hill Canal to the west of the HRRC

outfall. Although this site appears to be upstream of the HRRC outfall, field investigations showed that the

water pumped from HRRC can flow both east and west in the canal, so Site 5 can also be affected by the

discharge.

As in previous studies, Site 7 on Lake Christopher provides a point of comparison with Lake James. Site 9 is

located in the City landfill retention pond. Although the landfill retention pond does not discharge to the Ce-

dar Hill Canal, this site was sampled to support evaluations of whether the HRRC discharge could be di-

verted to the pond.


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Figure 1. Map of sampling locations for dry and wet weather events

2.2 Sampling Dates and Conditions

Table 1 contains the dates and weather events in which samples were collected.

Table 1. Sampling Dates and Site Conditions

Sample Date Season Event

9/8/2017 Warm Dry weather

9/14/2017 Warm Wet weather

10/24/2017 Cool Wet weather

11/6/2017 Cool Canal survey

11/16/2017 Cool Dry weather


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2.3 Field Methods

At each sampling site, the field crew used a YSI multimeter probe to measure temperature, pH, specific con-

ductance, and dissolved oxygen (DO) as well as a WQ770 meter to measure turbidity. These probes were

calibrated within 24 hours prior to sampling events. Both probes were rinsed twice with deionized (DI) water

before and in between immersing the sensors in sample water. Once the values displayed on the probe

screen stabilized, the field crew recorded measurements on a data sheet or a waterproof notebook when

necessary. During dry weather events, the field crew used single-person kayaks to access sites within Lake

James and Lake Christopher. The same parameters were measured at the surface of these sites as well as

every 3 feet down the water column to the bottom of the lake.

Grab samples were collected from each sample location. Parameters for local laboratory analysis were total

Kjeldahl nitrogen (TKN), nitrate-plus-nitrite, ammonia, total phosphorus, orthophosphate, and total sus-

pended solids (TSS) (Table 2). Ten percent of the samples collected were either duplicate samples or field

equipment blanks for quality assurance. At sites located near the shore, the field crew used a swing sampler

with sampling bottle to fill each of the laboratory bottles. Prior to filling the laboratory bottles, the field crew

labeled each bottle with the site identifier (ID), date and time sampled, and sampler’s name. This infor-

mation was also recorded on a data sheet and transferred to the laboratory chain-of-custody form. The swing

pole and bottle were rinsed twice with DI water before the first sample as well as between sample sites. Ad-

ditionally, the sampling crew rinsed the sampling bottle with sample water before officially collecting the

sample. For sites located within Lake James or Lake Christopher, the field crew used a pre-labeled labora-

tory bottle (with no preservative) to fill the smaller laboratory bottles. These bottles were sterilized in the la-

boratory; no DI rinse was required. For the in-lake sites, samples were also collected and shipped for analy-

sis of cyanobacteria, microcystins and nodularin, cylindrospermopsin, anatoxin-a, chlorophyll-a, and total

algal biomass.

For local analysis, the collected samples were immediately stored in a cooler with ice and delivered to the

laboratory within 48 hours. If the samples could not be delivered to the lab within 24 hours of collection, the

water samples were intentionally cooled below 6 degrees Celsius (°C) to aid preservation. For algal analysis,

the samples were placed in a small cooler with ample ice and shipped overnight on the day of sampling via

FedEx.

In addition to the wet and dry weather sampling events, the field crew performed a survey on Cedar Hill Ca-

nal. The purpose of this survey was to map the canal’s ammonia concentrations at a higher spatial solution

than was practical with grab samples, and to confirm that HRRC was the only significant source under dry

weather conditions. Ammonia concentrations and other field parameters were measured with a YSI multime-

ter probe. No grab samples were collected for this portion of the study. Probes were calibrated on the morn-

ing of the survey and rinsed with DI water prior to taking measurements. Investigators recorded measure-

ments approximately 1,000 feet downstream of the Lake James outlet and moved upstream in 150-foot

increments until they reached approximately 600 feet upstream of the HRRC outfall.

2.4 Laboratory Methods

Hampton Roads Sanitation District (HRSD) analyzed nutrient and sediment parameters in Virginia Beach.

Currently, HRSD is not accredited for algal analysis. For that reason, algal parameters were analyzed at

GreenWater Laboratories (GWL) in Palatka, Florida. Table 2 lists the analytes and corresponding methods of

analysis.


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Table 2. Laboratory Analysis Methods

Analyte Method Analyte Method

Ammonia EPA 350.1 Algal biomass SM-10200-H

Nitrate and nitrite EPA 353.2 Chlorophyll-a, -b,

-c SM-10200-H

TKN EPA 351.2 Corrected chloro-

phyll-a SM-10200-H

Orthophosphate EPA 365.1 Pheophytin SM-10200-H

Total phosphorus EPA 365.1 Anatoxin-a EPA 545

TSS SM 2540 D-2011 Microcystins and

nodularins EPA 546

Cylindrosper-

mopsin EPA 545

Section 3: Results This section presents the results from the September–November 2017 monitoring efforts on Lake James

and nearby waters. The results are presented in subsections by major parameter category. The subsequent

Section 4 (Discussion) draws upon the results in Section 3 to make inferences regarding pollutant sources

and controls on algae growth in Lake James.

3.1 Field Parameters

Results from the onsite measurements are reported in this section. Emphasis was placed on the spatial pat-

terns in water quality, including both the difference between stations and lake vertical profiles. Secondary

interpretations of interest were differences between the dry and wet weather sampling events, and between

the warm weather and cooler weather events.

3.1.1 Lake Profiles

Figures 2 through 5 represent the field parameter profiles measured in Lake James and Lake Christopher.

Results show that surface temperatures were similar between Lake James and Lake Christopher, both expe-

riencing higher surface temperatures in the warm months (Figure 2). Temperature stratification can be seen

in all sites except Lake Christopher in the cool months, which had similar temperatures in deep water in the

warm months, which is evidence of a fall turnover. In the warm months, deep water in the western area of

Lake James (Site 3) had cooler temperatures than the eastern part of the lake (Site 2) and Lake Christopher.

Temperature stratification was generally stronger during the warm weather events than during the cooler

weather events.


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Figure 2. Graph of temperature profile in Lake James (Sites 2 and 3) and Lake Christopher (Site 7)

As seen in Figure 3, pH in surface waters was consistently higher in Lake James than in Lake Christopher. In

addition, warmer months saw consistently higher pH surface water than during cooler months. Algal photo-

synthesis is a common cause of higher daytime pH values in lakes and ponds, which explains why pH was

higher near the surface and in the warmer months. Higher pH in Lake James would be consistent with higher

algal levels, compared with Lake Christopher. The pH was not observed to exceed Virginia’s water quality cri-

terion for pH (6–9 standard units [s.u.]).

Figure 3. Graph of pH profile in Lake James (Sites 2 and 3) and Lake Christopher (Site 7)

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As seen in Figure 4, specific conductance was higher in Lake James than in Lake Christopher. Specific con-

ductance in surface waters was similar between warm and cool months. The stratification pattern in specific

conductance was the inverse of the temperature stratification pattern, with higher values (denser water) on

the bottom.

Figure 4. Graph of specific conductance profile in Lake James (Sites 2 and 3) and Lake Christopher (Site 7)

As seen in Figure 5, distinct DO stratification was observed in all sites except Lake Christopher during the

cool months. In all sites, a sharp decrease in DO occurred deeper in the water column in the cool months. In

contrast, in the warm months, DO started to decrease higher in the water column. In Lake James, surface

waters in warm months had higher DO than in cool months; however, the inverse was true for Lake Christo-

pher. The low dissolved concentrations in the low portion of the water column are typical of stratified lakes.

In the epilimnion (i.e., upper layer), DO was not observed to fall below Virginia’s minimum water quality crite-

rion of 4.0 mg/L in either Lake James or Lake Christopher.

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Figure 5. Graph of dissolved oxygen profile in Lake James (Sites 2 and 3) and Lake Christopher (Site 7)

3.1.2 Spatial Patterns

This section interprets the spatial differences in field parameters observed during the probe-based survey

and synoptic sampling events. Figure 6 displays temperature results from the Cedar Hill Canal survey. Lake

James was slightly warmer than the canal, likely due to lower shading. The apparent downstream decrease

in canal temperature (Figure 7) may be partly due to the fact that the probe-based survey was performed

from downstream to upstream, and temperature increased over the course of the day. However, the shal-

lower depth and narrower width of the canal upstream of Centerville Turnpike may also contribute to high

temperatures in that segment. Otherwise, temperatures were similar across sample sites, excluding Site 5,

which was somewhat warmer, probably because it was very shallow and had little canopy cover (Figure 8).

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-20

-15

-10

-5

0

0 1 2 3 4 5 6 7 8 9

Hei

ght

of

Mea

sure

men

t (f

t)

Dissolved Oxygen (mg/L)



11


Figure 6. Map of spatial patterns of temperature in Cedar Hill Canal during the probe-based survey (11/6/2017)


12


Figure 7. Longitudinal profile of temperature in Cedar Hill Canal from upstream to downstream during the probe-

based survey (11/6/2017)

Figure 8. Graph of temperature at sample sites during the synoptic sampling events of (September–November 2017).

Mid-lake sites (2, 3, and 7) were only sampled during dry weather events. HRRC (site 8) was only actively pumping

during one of the four sample events.

LF = landfill.

Figure 9 displays the pH results from the canal survey. The pH was slightly higher in Lake James than in the

canal, likely because of higher algal photosynthesis in the lake. The pH was higher in the upstream portions

15

16

17

18

19

20

21

22

23

24

25

0 5 10 15 20 25 30 35 40 45

Tem

per

atu

re (

°C)

Sequence ID

0

5

10

15

20

25

30

35

Site 4 Site 5 Site 8 Site 1 Site 2 Site 3 Site 6 Site 7 Site 9

Cedar Hill Canal Lake James Lake Chris. LF Pond

Tem

per

atu

re (

°C)

Dry- Warm Wet- Warm Dry - Cool Wet - Cool


13


of the canal than in the downstream portion (Figure 10), probably because of increased dilution of the HRRC

discharge as it moved downstream. However, pH at all locations was within the typical range (6–8) of sur-

face water (USGS 2016). pH was also within the expected range during the synoptic sampling events, exclud-

ing Site 5, which had values greater than 9 during two of the three sampling events (Figure 11). The HRRC

discharge (Site 8) did not exceed pH = 9, so the high pH values at Site 5 are more likely due to localized al-

gae growth in the canal.

Figure 9. Map of spatial patterns of pH in Cedar Hill Canal during the probe-based survey (11/6/2017)


14


Figure 10. Longitudinal pattern of pH in Cedar Hill Canal from upstream to downstream during the probe-based

survey (11/6/2017)

Figure 11. Graph of pH at sample sites during the synoptic sampling events (September–November 2017). Mid-lake

sites (2, 3, and 7) were only sampled during dry weather events. HRRC (site 8) was only actively pumping during one

of the four sample events.

LF = landfill.

6.80

6.90

7.00

7.10

7.20

7.30

7.40

7.50

7.60

7.70

7.80

0 5 10 15 20 25 30 35 40 45

pH

Sequence ID

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

10.0



pH



15


Figure 12 displays the specific conductance results from the probe-based survey. Specific conductance in

the canal ranged from 0.29 to 1.37 mS/cm. Similarly, sample sites located downstream of the canal (Sites

1, 2, 3, and 6) had lower specific conductance than those located upstream (Sites 4, 5, 8, and 9; Figure 14).

Specific conductance was significantly lower in Lake James than in the canal. Lake Christopher was found to

have the lowest specific conductance of all the sites studied; specific conductance on Lake Christopher was

about half that of Lake James.

Freshwater typically has a specific conductance of 0.050 to 0.850 mS/cm (Hem 1989), ocean water is typi-

cally 50 mS/cm, and groundwater ranges from 0.05 mS/cm to 50 mS/cm (Sanders 1998). Site 8 (the HRRC

discharge) was found to have a moderately high specific conductance (~1.6 mS/cm). Similarly, canal Sites 4

and 5 were found to have consistently elevated specific conductance, regardless of whether groundwater

was actively being pumped at that time. This suggests that the canal contains a substantial proportion of

water derived from the HRRC discharge even when pumping is not active. Presumably, the discharge accu-

mulates in the canal and is not readily flushed under dry conditions or during small rain events.

Figure 12. Map of spatial patterns of specific conductance in Cedar Hill Canal during the probe-based survey (11/6/

2017)


16


Figure 13. Longitudinal profile of specific conductance in Cedar Hill Canal from upstream to downstream during the

probe-based survey (11/6/2017)

Figure 14. Graph of specific conductance at sample sites during the synoptic sampling events (September–November

2017). Mid-lake sites (2, 3, and 7) were only sampled during dry weather events. HRRC (site 8) was only actively

pumping during one of the four sample events.

LF = landfill.

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1.60

0 5 10 15 20 25 30 35 40 45

Spec

ific

Co

nd

uct

ance

(m

S/cm

)

Sequence ID

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1.60

1.80

2.00



Spec

ific

Co

nd

uct

ance

(m

S/cm

)



17


Figure 15 displays the DO results from the canal survey. Unlike other parameters studied, DO had no obvi-

ous longitudinal pattern in the Cedar Hill Canal. Virginia’s water quality criteria for DO are 4 mg/L (minimum)

and 5.0 mg/L (daily average). During the probe-based survey, only two points in the Cedar Hill Canal had DO

levels slightly lower than 4 mg/L. Most DO concentrations were consistently above this threshold in the ca-

nal; however, levels dropped below 2 mg/L at Site 4 during the wet, cool sampling event (Figure 17).

Sources of oxygen demanded in the canal include ammonia nitrification and decaying vegetation. DO con-

centrations were somewhat higher in Lake James than in nearby canal locations, and were similar between

Lake James and Lake Christopher.

Figure 15. Map of spatial patterns of dissolved oxygen in Cedar Hill Canal during the probe-based survey (11/6/2017)


18


Figure 16. Longitudinal profile of dissolved oxygen in Cedar Hill Canal from upstream to downstream during the

probe-based survey (11/6/2017)

Figure 17. Graph of dissolved oxygen at sample sites during the synoptic sampling events (September–November

2017). Mid-lake sites (2, 3, and 7) were only sampled during dry weather events. HRRC (site 8) was only actively

pumping during one of the four sample events.

LF = landfill.

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

0 5 10 15 20 25 30 35 40 45

Dis

solv

ed O

xyge

n (

mg/

L)

Sequence ID

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0



Dis

solv

ed O

xyge

n (

mg/

L)



19


3.2 Nitrogen

During the probe-based survey, ammonia-N was relatively high (>0.5 mg/L as N) in the Cedar Hill Canal, and

decreased from upstream to downstream (Figures 18 and 19). Ammonia concentrations were above 2 mg/L

until downstream of the outfall draining to Brandon Middle School. Upstream of that point, ammonia-N was

close to or above 3 mg/L on the day of the survey. The school outfall was not discharging on the day of the

survey, so the source of apparent dilution of ammonia at this point was not clear. Sequence ID point 5 repre-

sents the water draining directly from the HRRC pond (Site 4). This point had the highest ammonia concen-

trations in the entire canal. On the day of the probe-based survey, ammonia concentrations in Lake James

were significantly lower than in the Cedar Hill Canal (0.24–0.6 mg/L as N).

Based on the synoptic survey grab sample data, ammonia concentrations were not consistently different be-

tween warm and cool seasons or between wet and dry weather events (Figure 20). However, the cool, dry

event had a higher average ammonia concentration than the other seasons and weather events. Lake

James and Lake Christopher (Sites 2 and 3; Site 7, respectively) did not have significantly different average

ammonia concentrations. Site 4 had significantly higher ammonia than any of the other sites. When HRRC

was pumping water into its retention pond (Site 8), the ammonia concentrations were very similar to those

measured at Site 4. This shows that the major source of ammonia at Site 4 is discharge from HRRC (Site 8).

Virginia’s water quality criteria for ammonia are dependent on pH and temperature. No sites in Lake James

or the canal were observed to exceed Virginia’s acute ammonia criteria (Table 3). The chronic ammonia crite-

ria is expressed as a 30-day average value, and so should not be evaluated in individual grab samples. How-

ever, the 2017 results demonstrate the potential for exceedance of the chronic ammonia criteria in the ca-

nal if concentrations remain above ~3 mg/L for extended periods. The 2013 USEPA criteria is more stringent

(lower) than Virginia’s existing ammonia criteria, and Virginia is likely to adopt those criteria sometime in the

future. Ammonia was observed to exceed the 2013 ammonia criteria in a small number of canal samples

(Table 3).


20


Figure 18. Graph of ammonia concentrations in Cedar Hill Canal during the probe-based survey (11/6/2017)


21


Figure 19. Graph of ammonia-N concentrations in Cedar Hill Canal from upstream to downstream during the probe-

based survey (11/6/2017)

Figure 20. Graph of ammonia concentrations in study sites during the synoptic sampling events (September–

November 2017). Mid-lake sites (2, 3, and 7) were only sampled during dry weather events. HRRC (site 8) was only

actively pumping during one of the four sample events.

LF = landfill.

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

0 5 10 15 20 25 30 35 40 45

Am

mo

nia

(m

g/L

as N

)

Sequence ID

0.001

0.010

0.100

1.000

10.000



Am

mo

nia

(m

g/L

as N

)

Dry-Warm Wet-Warm Dry-Cool Wet-Cool


22


Table 3. Comparison of Ammonia Concentrations to State and Federal Water Quality Criteria

Location Site Date

Measured

Ammonia

(mg/L as N)

Virginia

Chronic

Criterion

(mg/L as N)

EPA 2013

Chronic

Criterion

(mg/L as N)

Virginia

Acute

Criterion

(mg/L as N)

EPA 2013

Acute

Criterion

(mg/L as N)

Cedar Hill

Canal

Site 4 9/8/2017 7.13 1.24 0.57 9.06 2.60

Site 5 9/8/2017 0.06 0.12 0.06 1.16 0.17

Site 4 9/14/2017 7.17 1.76 0.80 17.03 4.35

Site 5 9/14/2017 0.09 0.16 0.07 1.11 0.25

Site 8 9/14/2017 7.36 1.79 0.81 16.49 4.43

Site 4 10/24/2017 5.08 3.21 1.46 20.19 9.85

Site 4 11/16/2017 6.84 3.34 1.52 15.19 9.74

Site 5 11/16/2017 0.05 2.99 1.36 13.25 8.29

Lake James

Site 1 9/8/2017 0.02 1.06 0.48 7.22 2.11

Site 2 9/8/2017 0.02 1.12 0.51 7.50 2.26

Site 3 9/8/2017 0.01 0.91 0.41 5.84 1.75

Site 6 9/8/2017 0.02 1.57 0.71 12.36 3.58

Site 1 9/14/2017 0.02 1.29 0.59 9.06 2.74

Site 6 9/14/2017 0.04 1.74 0.79 13.02 4.13

Site 1 10/24/2017 0.01 1.78 0.81 7.08 4.11

Site 6 10/24/2017 0.02 3.01 1.37 13.25 8.36

Site 1 11/16/2017 0.17 4.38 1.99 22.66 15.15

Site 2 11/16/2017 0.15 3.51 1.60 16.76 10.58

Site 3 11/16/2017 0.15 2.67 1.22 16.23 7.41

Site 6 11/16/2017 0.14 1.81 0.82 10.51 4.24

Lake Chris. Site 7 9/8/2017 0.01 1.41 0.64 10.51 3.07

Site 7 11/16/2017 0.13 1.81 0.82 10.51 4.24

LF Pond

Site 9 9/8/2017 0.02 1.00 0.45 7.94 1.95

Site 9 9/14/2017 0.02 1.11 0.50 8.73 2.23

Site 9 10/24/2017 0.02 3.30 1.50 14.94 9.58

Site 9 11/16/2017 0.14 2.30 1.04 14.44 5.97

LF Pond = Landfill pond

Nitrite-plus-nitrate concentrations were relatively low at most sites. As seen in Figure 21, only Site 4 and Site

8 had nitrite and nitrate concentrations greater than 0.1 mg/L as N. Based on the synoptic survey grab sam-

ple data, significant differences were not found between site, season, or weather event. However, on aver-

age nitrite and nitrate concentrations were higher during the cool, dry event than during the other events. In

addition, nitrate and nitrite concentrations were essentially the same between Sites 4 and 8 while groundwa-

ter was actively being pumped. Concentrations were not significantly different between Lake James and

Lake Christopher.


23


Nitrite-plus-nitrate nitrogen accounts for only a minority (1 to 11 percent) of the total nitrogen in Cedar Hill

Canal (Site 4). Rather, the majority (25 to 88 percent) was in the form of ammonia-N. Similar to the canal,

both Lake James and Lake Christopher had more nitrogen contribution from ammonia (2 to 27 percent and

2 to 26 percent, respectively) than from nitrite and nitrate (2 to 4 percent and 2 to 6 percent, respectively).

Most of the nitrogen in the lakes was in the form of organic nitrogen (computed as TKN minus ammonia),

likely created by algal uptake of inorganic nitrogen.

Figure 21. Graph of nitrite and nitrate concentrations in study sites during the synoptic sampling events (September–



Bars with < above them represent concentrations below the limit of quantification (0.01 mg/L as N). LF = landfill.

No appreciable difference was observed in TKN concentrations between seasons or weather events (Figure

22). In addition, synoptic samples displayed no appreciable difference in TKN between Lake James and Lake

Christopher. TKN concentrations were found to be significantly higher at Site 4 on the canal than at any

other site. At Site 4, TKN concentrations were at least three times higher in the warm, dry event than during

the other events. Similar to ammonia and nitrite-plus-nitrate concentrations, when high-nitrogen water was

being actively pumped into the retention pond, TKN concentrations at Site 4 were very similar to those at

Site 8. Based on a comparison of ammonia concentrations (Figure 20) with TKN concentrations (Figure 21),

ammonia accounted for the majority (2 to 88 percent) of the TKN in the canal.

0.001

0.010

0.100

1.000



Nit

rite

an

d N

itra

te (

mg/

L as

N)


< < < < < < < < << < <<


24


Figure 22. Graph of total Kjeldahl nitrogen concentrations in study sites during the synoptic sampling events

(September–November 2017). Mid-lake sites (2, 3, and 7) were only sampled during dry weather events. HRRC (site

8) was only actively pumping during one of the four sample events.

Bars with < above them represent concentrations below the limit of quantification (0.5 mg/L). LF = landfill.

3.3 Phosphorus

As with nitrogen, total phosphorus concentrations were high in the Cedar Hill Canal relative to the lake sites.

In addition, total phosphorus concentrations were not significantly different between Lake James and Lake

Christopher. Concentrations were found to be appreciably higher at Sites 4, 5, and 8 than at the other sites

(Figure 23). When HRRC was actively pumping, total phosphorus was similar between Sites 4 and 8.

0.10

1.00

10.00

100.00



Tota

l Kje

ldah

l Nit

roge

n (

mg/

L)


< < < < < < <


25


Figure 23. Graph of total phosphorus concentrations in study sites during the synoptic sampling events (September–




Orthophosphate concentrations were found to be relatively low (≤ 0.06 mg/L as P) at all sites and in all sea-

sons (Figure 24). No appreciable difference was observed between phosphorus concentrations in Lake

James and Lake Christopher (Sites 2 and 3; Site 7, respectively). For all sites, average orthophosphate con-

centrations were below 0.04 mg/L as P. As with total phosphorus, both Sites 4 and 8 had very similar ortho-

phosphate concentrations. Based on the low orthophosphate concentrations, most of the total phosphorus

was probably in organic or particulate, non-bioavailable forms.

0.001

0.010

0.100

1.000

10.000



Tota

l Ph

osp

ho

rus

(mg/

L)


< < < < <


26


Figure 24. Graph of orthophosphate concentrations in study sites during the synoptic sampling events (September–



Bars with < above them represent concentrations below the limit of quantification (0.01 mg/L at P in all cases except: Site 1 during wet, cool event

0.02 mg/L as P). LF = landfill.

3.4 Total Suspended Solids

Excluding Sites 4, 5, and 8, TSS concentrations were consistently below 10 mg/L, regardless of season or

weather event. TSS concentrations were not significantly different between seasons or weather events, or

between Lake James and Lake Christopher. Results from Site 4 show high concentrations of suspended sed-

iments during the warm, dry season as well as the cool, wet season (Figure 25). Because of the shallow na-

ture of these sites, TSS concentrations might have been affected by resuspension from the bottom. In con-

trast to other parameters, Site 8 showed higher concentrations of TSS than Site 4 when HRRC was actively

pumping.

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07



Ort

ho

ph

osp

hat

e (m

g/L

as P

)


< <

<< < << <

<


27


Figure 25. Graph of total suspended solids concentrations in study sites during the synoptic sampling events

(September–November 2017). Mid-lake sites (2, 3, and 7) were only sampled during dry weather events. HRRC (site

8) was only actively pumping during one of the four sample events.


3.5 Chlorophyll-a and Algae

As seen in Table 4, total algal biomass was found to be higher in Lake James (Sites 2 and 3) than in Lake

Christopher (Site 7) in the warm season. However, in the cool season, total algal biomass was similar be-

tween lakes. Chlorophyll-a was relatively low at all sites during the 2017 sampling, and did not reflect active

bloom conditions.

Table 4. Total Algal Biomass (mg/L) in Lake James and Lake Christopher

Season Site 2

(Lake James)

Site 3

(Lake James)

Site 7

(Lake Christopher)

Warm 1.7 1.5 0.3

Cool 0.4 0.3 0.3

0.100

1.000

10.000

100.000

1,000.000

10,000.000



Tota

l Su

spen

ded

So

lids

(mg/

L)


< <


28


Figure 26. Graph of corrected chlorophyll-a during the dry weather sampling events (September–November 2017)

In both seasons, total cyanobacteria concentrations were an order of magnitude higher in Lake James than

in Lake Christopher during both warm and cool weather sampling events (Table 5). During the warm season,

Site 7 in Lake Christopher had the greatest amount of potentially toxigenic cyanobacteria of all three study

sites, but densities were relatively low. During the cool season, all sites had at least a 90 percent decrease

in the total number of cyanobacteria, compared to the warm season. However, the sites in Lake James had

higher potentially toxigenic cyanobacteria in the cool months, compared to warm months.

For context, the World Health Organization (WHO) has categorized cyanobacteria densities based on the risk

of acute health events from contact recreation (Chorus and Bartram 1999). The risk categories are low

(<20,000 cells/mL), moderate (20,000–100,000 cells/mL), high (100,000–10,000,000 cells/mL), and

very high (>10,000,000 cells/mL). These thresholds were developed with the assumption that the cyanobac-

teria population are dominated by potential toxin formers. In contrast, VDH uses thresholds based on a sin-

gle potentially toxigenic cyanobacteria taxon (Microcystis) rather than total cyanobacteria. Specifically, VDH

recommends that local health districts and environmental agencies should be alerted when Microcystis den-

sities become greater than 5,000 cells/mL, and that the public should be notified for concentrations greater

than 20,000 cells/mL.

Table 5. Cyanobacteria Density (cells/mL) in Lake James and Lake Christopher

Season Analyte Site 2

(Lake James)

Site 3

(Lake James)

Site 7

(Lake Christopher)

Warm Total 225,036 233,514 23,558

Potentially toxigenic 1,390 750 3,836

Cool Total 20,176 11,201 1,152

Potentially toxigenic 18,003 9,206 22

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

Site 2 Site 3 Site 7

Lake James Lake Christopher

Co

rrec

ted

Ch

loro

ph

yll-a

(ug/

L)

Warm Cool


29


The cyanobacteria densities reported in Table 5 do not indicate exceedance of the VDH thresholds in Lake

James or Lake Christopher. The warm weather samples in Lake James did exceed the WHO thresholds for

high risk for acute health effects, but the low densities of potentially toxigenic cyanobacteria suggest that the

actual risk was not high at the time of sampling. These sampling results do not represent large bloom events

in Lake James. Interestingly, the results appear to demonstrate that the total cyanobacteria density is not a

reliable indicator of the potentially toxigenic cyanobacteria density in Lake James. The results may also sug-

gest that the potentially toxigenic cyanobacteria may actually be favored under cooler weather conditions,

which would be consistent with the recent blooms (e.g., February 2017 and January 2018) that also oc-

curred in relatively cool conditions.

The cyanotoxin cylindrospermopsin was not detected in Lake Christopher in either season, but was detected

at both Lake James sites (Table 6). Cylindrospermopsin concentrations were higher at Site 3 than at Site 2,

and both of these sites had slightly higher cylindrospermopsin concentrations in the cool months. None of

the values approached EPA’s draft recreational advisory value (8 micrograms per liter [µg/L]). Other cyano-

toxins that were analyzed (microcystins, nodularins, and anatoxin-a), were not detected in any samples.

Table 6. Cyanotoxin Concentrations (ug/L) in Lake James and Lake Christopher

Season Analyte Site 2 Site 3 Site 7

Warm

Cylindrospermopsin 0.07 0.11 <0.05

Microcystins/nodularins <0.15 <0.15 <0.15

Anatoxin-a <0.05 <0.05 <0.05

Cool

Cylindrospermopsin 0.3 0.33 <0.05

Microcystins/nodularins <0.15 <0.15 <0.15

Anatoxin-a <0.05 <0.05 <0.05

Section 4: Discussion This section interprets the water quality data collected in 2017 regarding potential controls on algae in Lake

James. It starts with a brief review of the scientific literature about factors that can favor cyanobacteria

blooms (Section 4.1). This is followed by observations on potential nutrient limitations in Lake James (Sec-

tion 4.2). Finally, a conceptual model of the lake algae dynamics is presented in Section 4.3.

4.1 General Factors Affecting Cyanobacterial Blooms

General factors that affect cyanobacterial blooms are relevant to this investigation because an understand-

ing of these factors can support interpretations of why cyanobacterial blooms occur in Lake James and other

water bodies. Cyanobacteria are natural components of Virginia’s microflora, and commonly present in Vir-

ginia’s lakes and ponds (Marshall 2013). Cyanobacteria have generally increased regionally since 1985

(Marshall et al. 2008). Some factors that promote the expansion of cyanobacterial blooms include nutrient

over-enrichment, lake aging, increased temperatures, low light conditions, water column stability, and low

flushing rates (Pearl and Otten 2013; Rolland et al. 2013; Romo et al. 2012). In systems with low flushing

rates, the impact of eutrophication is exacerbated by the extended residence time within the waterway.

Blooms are also enabled by conditions that make it easier for cyanobacteria to remain near the surface

where solar radiation is more intense, such as lakes with vertical stratification and calm surfaces (Pearl and

Otten 2013). Moreover, some cyanobacteria have lower light requirements than competing algae, and thus

can thrive under turbid or low-light conditions (Dokulil and Teubner 2000). Human disturbances that cause


30


dramatic changes in environmental conditions make it easier for aggressive primary colonizing cyanobacte-

ria to bloom (Pearl and Otten 2013).

Beyond the general factors that promote cyanobacteria dominance, various environmental factors favor or

disfavor specific bloom-forming taxa. For example, some cyanobacteria are nitrogen-fixers, and thus can be

favored under low-nitrogen conditions (Blomqvist et al. 1994). Cyanobacteria can be highly variable in their

preferred temperature ranges and degree of water turbulence. Two genera that have been observed in Lake

James are Planktothrix and Aphanizomenon. These two taxa can occur in the same water body but are typi-

cally not dominant at the same time (Teubner et al. 1999). While nutrient availability plays a large role, the

dominant species in cyanobacteria blooms is heavily dependent on the species composition prior to when

proper nutrients become accessible (Teubner et al. 1999).

Planktothrix is a non-nitrogen fixing genus (Pearl and Otten 2013) with species that thrive in well-stratified

waters, such as P. rubenscens, and that favor well-mixed waters, P. agardhii and P. isothrix (Bonilla et al.

2001; Dokulil and Teubner 2000). Blooms of Planktothrix are often observed in nitrogen-rich lakes (Pearl

and Otten 2013), but some species are also good competitors in nitrogen-limited ecosystems (Teubner et al.

1999). This genus tolerates low light conditions and some species have even been shown to grow slower

under prolonged periods of intense light (Chorus and Bartram 1999). Compared to other genera with similar

environmental ranges, Planktothrix is highly competitive, especially under high phosphorus and low light con-

ditions (Bonilla et al. 2001; Teubner et al. 1999).

Aphanizomenon is a nitrogen-fixing genus, which makes it an excellent competitor in low-nitrogen systems

(Teubner et al. 1999; Dokulil and Teubner 2000). Like many other cyanobacteria, Aphanizomenon possess

gas vesicles that maintain their buoyancy and help keep them close to the water’s surface where light availa-

bility is highest. This is important because nitrogen fixation requires considerable amounts of energy (Chorus

and Bartram 1999). Although blooms typically occur during warm months, multiple varieties of Aphani-

zomenon flos-aquae have been shown to increase biomass in winter when populations of other phytoplank-

ton are less dense (Yamamoto 2009). While both genera are generally poor competitors in low-phosphorus

conditions (Teubner et al. 1999), studies have found that the species Aphanizomenon flos-aquae has a

lower affinity for phosphorus compared to Planktothrix agardhii (Dokulil and Teubner 2000). This difference

in affinity might be why Aphanizomenon abundance has been observed to change more dramatically be-

cause of seasonal nutrient shifts (Teubner et al. 1999).

The discussion above illustrates the array of physiological mechanisms, very broad tolerances, and adapta-

bility of cyanobacteria. These are among the reasons that these organisms have survived and thrived as one

of earth’s oldest organismal groups. It also highlights the difficulty in implementing strategies to control

these species, because their ubiquitous nature and ability to withstand various stresses often requires sub-

stantial effort and dramatic steps to prevent their proliferation.

4.2 Potential Nutrient Limitations in Lake James

Nitrogen-to-phosphorus (N:P) ratios are often studied alongside species composition of cyanobacteria in ar-

eas that frequently experience blooms (Teubner et al. 1999; Dokulil and Teubner 2000; Yamamoto 2009;

Pearl and Otten 2013). These ratios are one tool for diagnosing whether the algal biomass is more likely to

be limited by the nitrogen or phosphorus supply. As a general rule, molar N:P ratios >20:1 represent phos-

phorus-limited ecosystems, N:P ratios <5:1 represent nitrogen-limited systems, and intermediate N:P ratios

represent indeterminate or mixed limitation (Thomann and Mueller 1987). The ratios are calculated using

the molar ratios of dissolved inorganic nutrient species; i.e., as the sum of ammonia nitrate-plus-nitrate nitro-

gen over orthophosphorus. N:P ratios should not be taken as a definitive indication of nutrient limitation;

other factors (e.g., light) might impose more of a limitation than either nitrogen or phosphorus. However, the


31


ratios do provide insights into whether one nutrient is obviously much less abundant than the other, and

thus more likely to control growth rates.

Table 7 provides the ratios of inorganic N:P, as measured in this study. Some ratios are presented as cen-

sored (> or <) because they were computed from censored data. During all sampling events, Site 4 in the

Cedar Hill Canal had very high N:P ratios, driven mainly by the high ammonia concentrations at these sites.

However, Lake James and Lake Christopher appeared to experience either nitrogen or phosphorus limitation

at different times. It is notable that Lake James could sometimes experience a nitrogen or mixed limitation

despite the high nitrogen concentrations in the adjoining Cedar Hill Canal. A likely explanation is that much

of the ammonia-N from the canal is utilized or attenuated during periods when the canal is not flowing into

the lake, which represents most sampling conditions. Presumably, the N:P ratios in Lake James can be much

higher when the lake and canal are directly exchanging water, and phosphorus-limiting conditions would pre-

vail.

Table 7. Dissolved Inorganic Nitrogen: Orthophosphate Molar Ratios from Synoptic Sampling Events

Lake James Canal Lake Chris.

Weather

Event Site 1 Site 2 Site 3 Site 6 Site 4 Site 5 Site 7

Dry warm CC >7:1 <4:1 1:1 809:1 17:1 <3:1

Wet warm CC -- -- CC 555:1 CC --

Wet cool CC -- -- >7:1 >1176:1 -- --

Dry cool CC >35:1 >38:1 <33:1 >1693:1 40:1 >35:1

CC = cannot compute ratio, both values were censored.

Studies have shown that the most abundant cyanobacteria species in an area prior to ideal bloom condi-

tions often dictates which species will dominate during blooms (Teubner et al. 1999). During times when ni-

trogen is limiting and phosphorus is abundant, species of nitrogen-fixing cyanobacteria, such as Aphani-

zomenon flos-aquae, could be more common. On the other hand, during times of nitrogen abundance and

phosphorus limitations, cyanobacteria with high phosphorus affinities, such as Planktothrix agardhii, could

be favored. The fact that Lake James can experience either phosphorus or nitrogen limitation may explain

why either of these two cyanobacteria taxa can be dominant during different sampling events.

4.3 Conceptual Model of Lake James

Several of Lake James’ characteristics match those that the literature would indicate favor high algal bio-

mass and cyanobacterial blooms. These include:

• Low flushing rate: As a former borrow pit that usually does not experience flow-through from a perennial

stream, Lake James can be expected to have very low flushing rates and a long hydraulic retention time.

Although data is insufficient to construct an accurate hydrologic budget of the lake, simple consideration

of the lake volume, drainage area, and typical precipitation rates would indicate that the lake hydraulic

retention time could approach or exceed 2 years barring high rates of inflow from the Cedar Hill Canal.

The lake inlet/outlet channels are both on the west side of the lake, so water in much of the eastern por-

tion of the lake may have a longer retention time than the water near the inlet/outlet channels. High re-

tention times provide longer periods for algae to use the available nutrients, and lower rates of flushing

of the algae that is produced.


32


• Stratification and seasonal turnover: Monitoring in 2017 revealed that Lake James was relatively deep

(>40 feet) and subject to relatively strong stratification (Figures 2-5) with low DO concentrations in

deeper waters. Low DO in the deeper layer can lead to mobilization of phosphorus from the lake sedi-

ments, which can cause blooms when changing seasonal temperatures or wind may cause the lake to

turn over--i.e., mix vertically—and thus bring the nutrients up into the shallow layer where light is availa-

ble to support algal growth. The combination of stratification and low flushing can also lead to quiescent

water conditions, which can favor buoyant, scum-forming cyanobacteria over other taxa such as dia-

toms. Lake turnover can also resuspend dormant cyanobacterial algal cells from the lake bottom, allow-

ing them to multiply and lead to blooms. Recent bloom events have been more common in cooler

months (January–March), which suggests that the blooming taxa have a relative high range of tempera-

ture tolerance and may also be taking advantage of nutrients from waters that are isolated from the sur-

face by thermal stratification during the warmer months.

• Nutrient and sediment inputs from the watershed and the Cedar Hill Canal: The monitoring results pre-

sented in this TM are generally consistent with previous evaluations of the Cedar Hill Canal, which

showed higher levels of specific conductance, nitrogen, phosphorus, and suspended sediment in the

canal water, compared to Lake James. Unlike the results of Bass and Schafran (2009), the 2017 moni-

toring did not indicate that nutrient concentrations in Lake James were significantly higher than those in

Lake Christopher, but this is probably highly dependent on hydrologic conditions and whether the canal

is actively flowing into Lake James. Although Lake James may be prone to cyanobacterial occurrence

regardless of the canal, it is reasonable to conclude that the nutrient inputs from the canal are capable

of triggering and sustaining larger blooms than would otherwise occur. Turbidity from the canal might

favor cyanobacteria that can out-compete other taxa under low-light conditions. Because of the low

flushing rates of Lake James, “pulses” of canal water into the lake—followed by dry periods—could cause

input from the canal to remain in Lake James for weeks or months.

Lake Christopher shares with Lake James some of the same characteristics that favor cyanobacteria, such

as a relatively low flushing rate, stratification, and a developed watershed. The monitoring results of 2017

revealed that Lake Christopher is capable of hosting low to moderate densities of cyanobacteria, including

potentially toxigenic taxa. However, Lake Christopher was slightly shallower than Lake James, and did not

experience stratification as strong as that observed in Lake James. It is logical to posit that the canal inputs

are a major reason why Lake James experiences higher cyanobacterial densities than Lake Christopher. The

two lakes have similar characteristics and watershed, and even similar cyanobacteria taxa, with the main

differences being the magnitude of algal productivity, higher density of cyanobacteria, and the canal connec-

tion.

In summary, the authors conclude that Lake James is probably prone to relatively high algal growth rates

and cyanobacterial dominance by its “bathtub” character, which includes a low flushing rate and strong

stratification. Highly competitive taxa such as Aphanizomenon and Planktothrix can take advantage of both

internal and external nutrient sources when conditions are otherwise favorable. Which species blooms at a

given time may be controlled by antecedent temperature and nutrient conditions, and by species availability.

Inputs from the Cedar Hill Canal can temporarily increase nutrient concentrations and sustain larger blooms

than would occur without the canal inputs. The lake almost certainly has a supply of nutrients in bottom sedi-

ments that can sometimes be re-mobilized to support algal growth even when the canal is not actively flow-

ing into the lake. Hence, blooms may continue to occur in Lake James even if the canal water quality was

significantly improved, particularly during or soon after the lake mixes vertically in cooler weather.


33


Section 5: Conclusions and Recommendations The major conclusions of the 2017 monitoring of Lake James and nearby waters can be stated as follows:

1. Lake James had relatively favorable water quality conditions during the 2017 sampling events. During

the five 2017 sampling events (including the May 2017 event), algal concentrations were relatively low,

and nutrient concentrations were comparable with those in Lake Christopher. Although cyanobacteria

were present in Lake James at higher densities than in Lake Christopher, cyanotoxins were not detected

above advisory thresholds. These sampling conditions did not reflect active algal blooms or discharges

from the canal into the lake. The sampling results reveal that Lake James can experience relatively good

water quality under the observed conditions.

2. The Cedar Hill Canal was confirmed to have elevated concentrations of nutrients derived from HRRC.

The 2017 water quality monitoring evaluation generally confirmed previous findings that the Cedar Hill

Canal experiences elevated concentrations of several constituents—most notably ammonia-N—derived

primarily from the HRRC discharge. This discharge appears to be complying with its effluent permit limits

and was not observed to cause exceedances of Virginia’s water quality criteria for ammonia.

3. Lake James can experience either phosphorus- or nitrogen-limiting conditions for algal growth. The

simple evaluation of N:P ratios revealed that Lake James might experience either phosphorus or nitro-

gen limitation at different times. Under nitrogen-limiting conditions, algal productivity in the lake would

be more sensitive to ammonia inputs from the Cedar Hill Canal or watershed. The mixed or alternating

limitation may explain why different cyanobacteria taxa—including nitrogen fixers and non-nitrogen fix-

ers—are dominant during different bloom events.

4. Lake James has characteristics unrelated to the canal that may favor periodic cyanobacteria blooms.

Lake James’ long retention time, stratification/turnover cycles, and developed watershed make it prone

to harbor a moderate cyanobacteria biomass regardless of the canal water quality. This is evidenced by

the fact that Lake Christopher also had moderate densities of cyanobacteria. However, it is reasonable

to conclude that the nutrient inputs from the canal are capable of triggering and sustaining larger

blooms in Lake James than would otherwise occur.

The following are specific recommendations that could limit the adverse effects of cyanobacteria blooms in

Lake James:

1. Implement best management practices in direct discharge areas. Reduction of nutrient loading is often

the most effective way to reduce both the frequency and magnitude of cyanobacteria blooms. Infor-

mation is currently insufficient to quantify the proportion of nutrient inputs to Lake James that are de-

rived from the 326-acre direct drainage area versus the Cedar Hill Canal. This is primarily due to the lack

of information on the seasonal and annual volumes of water passing between the canal and the lake.

Regardless, it would be recommended that residents of the watershed continue to reduce nutrient loads

from suburban sources. Such measures include avoidance of lawn fertilization near the lake, collection

of pet waste, keeping yard waste out of streets, and prevention of irrigation runoff.

2. Divert the HRRC discharge from the Cedar Hill Canal, or reduce its nutrient content. Based on 2017

sampling results, the HRRC discharge is the primary source of nutrients in the Cedar Hill Canal (Figures

20, 23). This discharge appears to be complying with its effluent permit limits and was not observed to

cause exceedances of Virginia’s water quality for ammonia. However, as discussed above, it is a poten-

tial contributor to algal blooms in Lake James. Given the importance of Lake James for stormwater man-

agement and downstream flood control, it is more feasible to improve the quality of the HRRC discharge

than to disconnect the canal from Lake James under all hydrologic conditions.

The City is currently evaluating the feasibility of diverting the HRRC discharge away from the Cedar Hill

Canal. In addition, HRRC is expected to stop dewatering its pit in 5 to 7 years, after which the discharge


34


will consist primarily of stormwater runoff routed through a retention basin yet to be built (personal com-

munication, Charles Plott, HRRC, November 30, 2017). The quality of the discharge to the Cedar Hill Ca-

nal is expected to be significantly improved at that time, and groundwater-derived ammonia may be

largely absent.

3. Conduct algacide treatments as needed. Although prevention of algae blooms is a preferred technique,

Lake James is likely to experience periodic cyanobacteria blooms even if the canal water quality is im-

proved. For this reason, algacide treatments may continue to sometimes be necessary. It should be em-

phasized that algacide treatments do not make it safe to have contact recreation in water affected by

cyanobacterial blooms, and can in fact temporarily increase cyanotoxin concentrations. Contact recrea-

tion is not recommended in Lake James or any other stormwater management facility regardless of

whether a bloom is present.

4. Perform artificial mixing or aeration. Several related categories of in-lake management techniques are

sometimes effective for reducing cyanobacterial blooms. Aeration can maximize the ability of a lake to

absorb phosphorus, prevent phosphorus re-mobilization, and enhance the nitrification of ammonia

(Holmroos et al. 2016). Increasing turbulence in the water column can favor non-cyanobacteria taxa

(e.g., diatoms) over buoyant cyanobacteria (Huisman et al. 2004; Visser et al. 2015). These techniques

have a mixed record of success for controlling cyanobacteria, and some of the failures can be attributed

to under-sizing the systems so that the necessary level of turbulence and destratification was not

achieved (Goodwin 2016). If this option were pursued for Lake James, it would be recommended to

carefully consider Lake James’ specific characteristics. Larger systems are more likely to be effective,

but also have higher capital and operational costs.

Other potential in-lake treatment includes dredging of nutrient-rich lake sediments and alum treatments,

which are intended to prevent the mobilization of phosphorus from the bottom sediments. Dredging is a

cost-prohibitive option in most lake settings. The potential effectiveness of alum treatment would de-

pend upon the sediment phosphorus content and the relative magnitude of this nutrient source com-

pared to external inputs. Due to uncertainties in this regard, it would first be recommended to address

known nutrient sources (e.g., improving the canal water quality) prior to employing costly in-lake man-

agement methods of uncertain effectiveness.


35


References Bass, L. and Schafran, G. 2009. Lake James Water Quality Study: Ten Week Update. Report prepared for the Lake James

Homeowner’s Association. 10 p.

Blomqvist, P., A. Pettersson and P. Hyenstrand, 1994. Ammonium nitrogen: A key regulatory factor causing dominance of

nonnitrogen-fixing cyanobacteria in aquatic systems. Arch. Hydrobiol. 132: 141–164.

Bonilla, S., L. Aubriot, M.C.S. Soares, M. González-Piana, A. Fabre, V. L.M. Huszar, M. Lürling, D. Antoniades, J. Padisák, C.

Kurk, “What drives the distribution of the bloom-forming cyanobacteria Planktothrix agardhii and Cylindrospermopsis

raciborskii?” FEMS Microbiology Ecology, March 2001, Volume 79, Issue 3, 594–607 p.

Chorus, I., and Bartram, J. 1999. Toxic Cyanobacteria in Water: A guide to their public health consequences, monitoring and

management. World Health Organization report. 400 p.

Dokulil, M.T. and K. Teubner, “Cyanobacterial dominance in lakes,” Hydrobiologia, June 2000, Volume 438, 1–12 p.

Goodwin, P. 2016. Aeration Effect on Algae: A Review of Success and Failures. Presentation to the 2016 Michigan Inland

Lakes Convention. 33 p.

Hem, J.D. Study and Interpretation of the Chemical Characteristics of Natural Water. U.S. Geological Survey Water-Supply Pa-

per 2254, 1989, 263 p.

Holmroos, H., Horppila, J., Laakso, S., Niemisto, J., and Hietanen, S. 2016. Aeration-Induced Changes in Temperature and

Nitrogen Dynamics in a Dimictic Lake. J Environ Qual. 2016 Jul;45(4):1359–1366

Huisman J., Sharples J., Stroom J.M., Visser P.M., Kardinaal W.E.A., Verspagen J.M.H., Sommeijer B. 2004. Changes in turbu-

lent mixing shift competition for light between phytoplankton species. Ecology 85:2960–2970.

Malcolm Pirnie. 2009. Lake James and City of Virginia Beach Landfill No. 2 Phase 2 Water Quality Assessment. Technical

memo from Steve Nesbitt to Phil Davenport, prepared on behalf of the City of Virginia Beach. 18 p.

Marshall, H.G., Burchardt, L., Egerton, T.A., Stefaniak, K., and Lane, M. 2008. Potentially toxic cyanobacteria in Chesapeake

Bay and a Virginia Lake. in Cyanobacterial Harmful Algal Blooms: State of the Science and Research Needs. H. Kenneth

Hudnell, ed. Springer Science.

Marshall. 2013. Phytoplankton in Virginia Lakes and Reservoirs. Virginia Journal of Science, 64 (1-1), 3–15.

Pearl, H.W. and T.G. Otten, “Harmful Cyanobacterial Blooms: Causes, Consequences, and Controls,” Microb. Ecol., May 2013,

Volume 65, Issue 4. 995–1010 p.

Rolland, D.C., Bourget, S., Warren, A., Laurion, I., and Vincent, W. 2013. Extreme variability of cyanbacterial blooms in an ur-

ban drinking water supply. Journal of Plankton Research 35(4): 744–758.

Romo, S., Soria, J., Fernandez, F., Oauhid, Y., and Baron-Sola, A. 2012. Water residence time and the dynamics of toxic cyano-

bacteria. Freshwater Biology 58 (3): 513–522.

Sanders, L.L., A Manual of Field Hydrogeology, Prentice Hall Professional Technical Reference, Upper Saddle River, NJ, March

18, 1998, 381p.

Teubner, K., R. Feyerabend, M. Henning, A. Nicklisch, P. Woitke, and J.G. Kohl, “Alternative blooming of Aphanizomenon flow-

aquae or Planktothrix agardhii induced by the timing of the critical nitrogen: phosphorus ration in hypertrophic riverine

lakes,” Arch. Hydrobiol. Spec. Issues Advanc. Limnol. April 1999, Volume 54, 325-344 p.

Thomann, R.V., and Mueller, J.A. 1987. Principles of Surface Water Quality Modeling and Control. Harper and Row Publishers,

New York, N.Y. 644 p.

U.S. Geological Survey (USGS). 2016. “pH- Water Properties,” https://water.usgs.gov/edu/ph.html (December 19, 2017)

Visser, P.M., Ibelings, B.W., Bormans, M., and Huisman, J. 2015. Artificial mixing to control cyanobacterial blooms: a review.

Aquatic Ecology 50(3): 423–441.

Yamamoto, Y., “Environmental factors that determine the occurrence and seasonal dynamics of Aphanizomenon flos-aquae,”

Journal of Limnology, February 2009, Volume 68, Issue 1, 122–132 p.

https://water.usgs.gov/edu/ph.html


36


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A-1


Attachment A: Water Quality Monitoring Data


A-2




A-3


Table A1-1. Raw Data Measured at Shore Adjacent Sites

Weather

Event Site Date Time

Tempera-

ture (°C) pH

Specific

Conduct-

ance

(mS/cm)

Dissolved

Oxygen

(mg/L)

Turbidity

(NTU) Comments

Dry 1 9/8/2017 11:40 25.6 8.08 0.279 6.84 2

Several ducks and turtles observed at time

of sampling. Duplicate sample collected at

Site 1.

Dry 4 9/8/2017 14:45 25.8 7.96 1.580 7.36 1,671++ Notably more turbid than Site 5. Very shal-

low, muddy water.

Dry 5 9/8/2017 14:30 34 9.09 1.430 9.99 1671 Shallow water, unable to avoid disturbing

bottom during sampling.

Dry 6 9/8/2017 11:30 25.7 7.79 0.280 6.58 2 No comments

Dry 8 9/8/2017 NA NA NA NA NA NA No water being pumped during visit. Next

closest sampling point was at Site 4.

Dry 9 9/8/2017 2:15 27.7 8.03 0.530 7.87 13.5 Sample taken where pump hose leads into

the water.

Wet 1 9/14/2017 14:25 25.2 7.96 0.283 7.17 2 No comments

Wet 4 9/14/2017 15:50 27.2 7.60 1.580 9.38 97 No comments

Wet 5 9/14/2017 15:15 28.7 9.12 1.930 13.82 604

Canal was dry directly before the outfall,

sampled ~800 ft upstream at the first area

with standing water.

Wet 6 9/14/2017 14:20 24.6 7.76 0.284 6.50 2 No comments

Wet 8 9/14/2017 16:10 26.6 7.62 1.590 8.00 101.5 Heavy flow at time of sampling. Collected

sample directly from outflow.

Wet 9 9/14/2017 15:00 27.2 7.98 0.530 8.25 6 No comments

Wet 1 10/24/2017 8:35 21.7 7.88 0.286 7.08 0 No comments

Wet 4 10/24/2017 9:55 20.2 7.63 1.260 1.06 54.2 No comments

Wet 5 10/24/2017 NA NA NA NA NA NA Canal had no standing water.

Wet 6 10/24/2017 8:50 21.7 7.88 0.286 7.08 0 No comments

Wet 8 10/24/2017 NA NA NA NA NA NA No water being pumped during visit. Next



A-4


Table A1-1. Raw Data Measured at Shore Adjacent Sites

Weather

Event Site Date Time

Tempera-

ture (°C) pH

Specific

Conduct-

ance

(mS/cm)

Dissolved

Oxygen

(mg/L)

Turbidity

(NTU) Comments

Wet 9 10/24/2017 9:15 21.4 7.70 0.540 6.73 0 No comments

Dry 1 11/16/2017 13:15 16.3 7.75 0.289 7.31 NR No comments

Dry 4 11/16/2017 15:29 19.4 7.49 1.610 5.08 NR

Noticeably clearer than any other visit.

Small fish could be seen in the ponded wa-

ter.

Dry 5 11/16/2017 16:16 17.3 8.09 1.830 6.44 NR

Construction had recently been done at the

outfall. Small pools of water were present

near the sampling point but further up-

stream was too shallow (where water was

pooling) to sample.


Dry 8 11/16/2017 NA NA NA NA NA NA No water being pumped during visit. Next




A-5


Table A1-2. Raw Data Measured at In-Lake Sites

Site Date Time Depth Site/Depth

ID

Tempera-

ture (°C) pH

Specific

Conduct-

ance

(mS/cm)

Dissolved

Oxygen

(mg/L)

Turbid-

ity

(NTU)

Comments

2 9/8/2017 10:10 Sur-

face 2_00 25.2 8.06 0.28 8.11 2.0 No comment

2 9/8/2017 10:10 -3 ft 2_03 25.2 8.16 0.281 8.13 2.0 No comment

2 9/8/2017 10:10 -6 ft 2_06 25.2 8.16 0.281 8.05 2.0 No comment

2 9/8/2017 10:10 -9 ft 2_09 25.2 8.17 0.281 8.19 2.0 No comment

2 9/8/2017 10:10 -12 ft 2_12 25.2 8.16 0.281 8.25 2.5 No comment

2 9/8/2017 10:10 -15 ft 2_15 25.2 8.16 0.281 8.35 2.5 No comment

2 9/8/2017 10:10 -18 ft 2_18 25.1 8.15 0.281 8.14 3.0 No comment

2 9/8/2017 10:10 - 21 ft 2_21 21.4 7.37 0.304 2.15 3.0 No comment

2 9/8/2017 10:10 -24 ft 2_24 17.2 7.15 0.314 1.03 3.0 No comment

2 9/8/2017 10:10 -27 ft 2_27 14.8 7.17 0.333 0.09 4.5 No comment

2 9/8/2017 10:10 -30 ft 2_30 15.0 7.22 0.342 0.05 3.0 No comment

2 9/8/2017 10:10 -33 ft 2_33 15.4 7.26 0.334 0.05 NA No comment

2 9/8/2017 10:10 -36 ft 2_36 15.5 7.24 0.337 0.05 NA No comment

2 9/8/2017 10:10 -39 ft 2_39 16.0 7.16 0.312 0.07 NA No comment

2 9/8/2017 10:10 -42 ft 2_42 15.8 7.14 0.3 0.06 NA No comment

3 9/8/2017 10:45 Sur-

face 3_00 25.3 8.19 0.281 8.24 39.0 No comment

3 9/8/2017 10:45 -3 ft 3_03 25.3 8.19 0.281 8.18 15.0 No comment

3 9/8/2017 10:45 -6 ft 3_06 25.2 8.19 0.281 8.21 13.0 No comment

3 9/8/2017 10:45 -9 ft 3_09 25.2 8.19 0.281 8.25 10.5 No comment

3 9/8/2017 10:45 -12 ft 3_12 25.2 8.19 0.281 8.22 9.0 No comment

3 9/8/2017 10:45 -15 ft 3_15 25.2 8.19 0.281 8.28 3.0 No comment


A-6




ID

Tempera-

ture (°C) pH

Specific

Conduct-

ance

(mS/cm)

Dissolved

Oxygen

(mg/L)

Turbid-

ity

(NTU)

Comments

3 9/8/2017 10:45 -18 ft 3_18 25.2 8.19 0.281 8.35 5.0 No comment

3 9/8/2017 10:45 - 21 ft 3_21 25.2 8.19 0.281 8.35 3.0 No comment

3 9/8/2017 10:45 -24 ft 3_24 22.8 7.53 0.296 3.84 3.0 No comment

3 9/8/2017 10:45 -27 ft 3_27 16.1 7.15 0.316 0.43 3.0 No comment

3 9/8/2017 10:45 -30 ft 3_30 12.1 7.12 0.341 0.03 NA No comment

3 9/8/2017 10:45 -33 ft 3_33 11.4 7.17 0.341 0.03 NA No comment

3 9/8/2017 10:45 -36 ft 3_36 11.2 7.19 0.398 0.02 NA No comment

3 9/8/2017 10:45 -39 ft 3_39 11.3 7.22 0.407 0.02 NA No comment

7 9/8/2017 12:20 Sur-

face 7_00 25.6 7.88 0.130 8.26 5.5 No comment

7 9/8/2017 12:20 -3 ft 7_03 25.6 7.86 0.133 7.75 4.0 No comment

7 9/8/2017 12:20 -6 ft 7_06 25.6 7.83 0.133 8.03 4.0 No comment

7 9/8/2017 12:20 -9 ft 7_09 25.4 7.81 0.133 8.18 4.0 No comment

7 9/8/2017 12:20 -12 ft 7_12 25.4 7.78 0.133 8.18 4.0 No comment

7 9/8/2017 12:20 -15 ft 7_15 25.3 7.73 0.133 7.71 4.0 No comment

7 9/8/2017 12:20 -18 ft 7_18 19.0 7.35 0.149 0.19 4.0 No comment

7 9/8/2017 12:20 - 21 ft 7_21 21.0 7.15 0.141 2.14 4.0 No comment

7 9/8/2017 12:20 -24 ft 7_24 14.7 7.21 0.217 0.04 4.0 No comment

7 9/8/2017 12:20 -27 ft 7_27 14.9 7.33 0.215 0.04 6.0 No comment

7 9/8/2017 12:20 -30 ft 7_30 15.0 7.41 0.194 0.03 NA No comment

7 9/8/2017 12:20 -33 ft 7_33 15.1 7.4 0.215 0.02 NA No comment

7 9/8/2017 12:20 -36 ft 7_36 15.3 7.42 0.191 0.02 NA No comment


A-7




ID

Tempera-

ture (°C) pH

Specific

Conduct-

ance

(mS/cm)

Dissolved

Oxygen

(mg/L)

Turbid-

ity

(NTU)

Comments

2 11/16/2017 11:21 Sur-

face 2_00 16.1 7.68 0.289 7.91 NA

Turbidity meter not functional on

day of the sampling

2 11/16/2017 11:22 -3 ft 2_03 16.1 7.65 0.289 7.72 NA No comment

2 11/16/2017 11:23 -6 ft 2_06 16.0 7.64 0.289 7.67 NA No comment

2 11/16/2017 11:24 -9 ft 2_09 15.9 7.62 0.289 7.59 NA No comment

2 11/16/2017 11:24 -12 ft 2_12 15.9 7.62 0.289 7.51 NA No comment

2 11/16/2017 11:26 -15 ft 2_15 15.9 7.62 0.289 7.50 NA No comment

2 11/16/2017 11:28 -18 ft 2_18 15.9 7.62 0.289 7.51 NA No comment

2 11/16/2017 11:29 - 21 ft 2_21 15.9 7.63 0.288 7.59 NA No comment

2 11/16/2017 11:30 -24 ft 2_24 15.9 7.63 0.288 7.55 NA No comment

2 11/16/2017 11:30 -27 ft 2_27 15.9 7.63 0.288 7.60 NA No comment

2 11/16/2017 11:31 -30 ft 2_30 15.9 7.63 0.289 7.53 NA No comment

2 11/16/2017 11:32 -33 ft 2_33 13.5 7.09 0.352 0.60 NA No comment

2 11/16/2017 11:33 -36 ft 2_36 11.5 7.06 0.356 0.31 NA No comment

2 11/16/2017 11:34 -39 ft 2_39 11.3 6.98 0.38 0.27 NA No comment

2 11/16/2017 11:35 -42 ft 2_42 11.9 7.01 0.451 0.24 NA No comment

2 11/16/2017 11:36 -45 ft 2_45 12.4 6.99 0.491 0.23 NA No comment

2 11/16/2017 11:37 -48 ft 2_48 12.7 6.98 0.497 0.21 NA No comment

2 11/16/2017 11:38 -51 ft 2_51 13.7 6.99 0.495 0.19 NA No comment

2 11/16/2017 11:45 -54 ft 2_54 11.9 7.06 0.407 0.30 NA No comment

2 11/16/2017 11:47 -57 ft 2_57 12.1 6.99 0.536 0.25 NA No comment

2 11/16/2017 11:48 -60 ft 2_60 12.4 6.98 0.537 0.24 NA No comment

2 11/16/2017 11:48 -63 ft 2_63 12.6 6.98 0.536 0.24 NA No comment


A-8




ID

Tempera-

ture (°C) pH

Specific

Conduct-

ance

(mS/cm)

Dissolved

Oxygen

(mg/L)

Turbid-

ity

(NTU)

Comments

2 11/16/2017 11:49 -66 ft 2_66 13.5 6.99 0.532 0.18 NA No comment

2 11/16/2017 11:51 -69 ft 2_69 15.6 7.03 0.520 0.18 NA Spec. Cond fluctuated between

0.5-0.535, mostly around 0.520

2 11/16/2017 11:52 -72 ft 2_72 15.6 7.04 0.530 0.18 NA No comment

2 11/16/2017 11:53 -75 ft 2_75 15.6 7.06 0.502 0.18 NA No comment

2 11/16/2017 11:54 -78 ft 2_78 15.9 7.07 0.502 0.17 NA

Mud residue was found on the

probe when pulled back to the sur-

face

3 11/16/2017 12:13 Sur-

face 3_00 16.1 7.67 0.289 7.62 NA No comment

3 11/16/2017 12:14 -3 ft 3_03 16.1 7.66 0.289 7.64 NA No comment

3 11/16/2017 NR -6 ft 3_06 16.0 7.66 0.289 7.60 NA No comment





3 11/16/2017 12:18 - 21 ft 3_21 15.9 7.63 0.289 7.40 NA No comment

3 11/16/2017 12:19 -24 ft 3_24 15.9 7.63 0.289 7.37 NA No comment

3 11/16/2017 12:20 -27 ft 3_27 15.9 7.62 0.289 7.29 NA No comment

3 11/16/2017 12:21 -30 ft 3_30 11.9 7.13 0.570 0.25 NA No comment






A-9




ID

Tempera-

ture (°C) pH

Specific

Conduct-

ance

(mS/cm)

Dissolved

Oxygen

(mg/L)

Turbid-

ity

(NTU)

Comments


3 11/16/2017 NR -48 ft 3_48 12.1 6.97 0.470 0.13 NA

Observed cord was at ~45° angle,

potentially due to wind pushing

the boat or current pushing the

water




3 11/16/2017 NR - 60 ft 3_60 13.7 6.97 0.467 0.11 NA No comment

3 11/16/2017 12:29 -63 ft 3_63 14.6 7.00 0.458 0.10 NA No comment

7 11/16/2017 2:31 Sur-

face 7_00 15.6 7.41 0.138 8.40 NA No comment






7 11/16/2017 2:35 -18 ft 7_18 15.5 7.34 0.138 8.40 NA No comment

7 11/16/2017 NR - 21 ft 7_21 15.4 7.32 0.138 8.30 NA No comment



7 11/16/2017 2:38 -30 ft 7_30 15.3 7.27 0.146 7.36 NA No comment




A-10




ID

Tempera-

ture (°C) pH

Specific

Conduct-

ance

(mS/cm)

Dissolved

Oxygen

(mg/L)

Turbid-

ity

(NTU)

Comments



7 11/16/2017 2:43 -45 ft 7_45 15.4 7.16 0.145 7.49 NA No comment

7 11/16/2017 2:45 -48 ft 7_48 15.4 7.23 0.124 7.67 NA No comment

7 11/16/2017 2:46 -51 ft 7_51 15.4 7.25 0.125 7.75 NA No comment


A-11


Table A1-3. Results from HRSD Lab: Nutrient and Sediment

Sample ID Sample Date Weather

Event Analyte

Result

(mg/L)

Below Level of

Quantitation

(Y/N)

Flag

LJ_01 9/8/2017 Dry Total Kjeldahl nitrogen 0.50 Y Above temp.

LJ_01 9/8/2017 Dry Total phosphorus 0.01 Y Above temp.

LJ_01 9/8/2017 Dry Nitrate + nitrite as N 0.01 Y Above temp.

LJ_01 9/8/2017 Dry Ammonia as N 0.02 N Above temp.

LJ_01 9/8/2017 Dry Orthophosphate as P 0.01 Y Above temp.

LJ_01 9/8/2017 Dry Total suspended solids 6.30 N Above temp.

LJ_01_Dup 9/8/2017 Dry Total Kjeldahl nitrogen 0.51 N Above temp.

LJ_01_Dup 9/8/2017 Dry Total phosphorus 0.01 Y Above temp.

LJ_01_Dup 9/8/2017 Dry Nitrate + nitrite as N 0.01 Y Above temp.

LJ_01_Dup 9/8/2017 Dry Ammonia as N 0.01 N Above temp.

LJ_01_Dup 9/8/2017 Dry Orthophosphate as P 0.01 Y Above temp.

LJ_01_Dup 9/8/2017 Dry Total suspended solids 2.00 N Above temp.


LJ_02 9/8/2017 Dry Total phosphorus 0.01 Y Above temp.

LJ_02 9/8/2017 Dry Nitrate + nitrite as N 0.01 N Above temp.



LJ_02 9/8/2017 Dry Total suspended solids 1.00 Y Above temp.


LJ_03 9/8/2017 Dry Total phosphorus 0.01 N Above temp.



LJ_03 9/8/2017 Dry Orthophosphate as P 0.01 N Above temp.

LJ_03 9/8/2017 Dry Total suspended solids 1.00 Y Above temp.

LJ_04 9/8/2017 Dry Total Kjeldahl nitrogen 28.10 N Above temp.





LJ_04 9/8/2017 Dry Total suspended solids 4,73 N Above temp.






A-12




Event Analyte

Result

(mg/L)

Below Level of

Quantitation

(Y/N)

Flag


LJ_05 9/8/2017 Dry Total suspended solids 115 N Above temp.











LJ_07 9/8/2017 Dry Orthophosphate as P 0.02 N N/A


LJ_08 9/8/2017 Dry Total Kjeldahl nitrogen N/A N/A N/A

LJ_08 9/8/2017 Dry Total phosphorus N/A N/A N/A

LJ_08 9/8/2017 Dry Nitrate + nitrite as N N/A N/A N/A

LJ_08 9/8/2017 Dry Ammonia as N N/A N/A N/A

LJ_08 9/8/2017 Dry Orthophosphate as P N/A N/A N/A

LJ_08 9/8/2017 Dry Total suspended solids N/A N/A N/A







LJ_01 9/14/2017 Wet Total Kjeldahl nitrogen 0.50 Y N/A

LJ_01 9/14/2017 Wet Total phosphorus 0.01 N N/A

LJ_01 9/14/2017 Wet Nitrate + nitrite as N 0.01 Y N/A

LJ_01 9/14/2017 Wet Ammonia as N 0.02 N N/A

LJ_01 9/14/2017 Wet Orthophosphate as P 0.01 Y N/A

LJ_01 9/14/2017 Wet Total suspended solids 7.50 N N/A

LJ_04 9/14/2017 Wet Total Kjeldahl nitrogen 8.47 N N/A



A-13




Event Analyte

Result

(mg/L)

Below Level of

Quantitation

(Y/N)

Flag

LJ_04 9/14/2017 Wet Nitrate + nitrite as N 0.36 N N/A


LJ_04 9/14/2017 Wet Orthophosphate as P 0.03 N N/A







LJ_05 9/14/2017 Wet Total suspended solids 74 N N/A




















LJ_01 10/24/2017 Wet Total phosphorus 0.01 Y N/A



LJ_01 10/24/2017 Wet Orthophosphate as P 0.02 Y Possible matrix

interference


A-14




Event Analyte

Result

(mg/L)

Below Level of

Quantitation

(Y/N)

Flag








LJ_04_Dup 10/24/2017 Wet Total Kjeldahl nitrogen 8.24 N N/A

LJ_04_Dup 10/24/2017 Wet Total phosphorus 0.54 N N/A

LJ_04_Dup 10/24/2017 Wet Nitrate + nitrite as N 0.23 N N/A

LJ_04_Dup 10/24/2017 Wet Ammonia as N 5.12 N N/A

LJ_04_Dup 10/24/2017 Wet Orthophosphate as P 0.02 N N/A

LJ_04_Dup 10/24/2017 Wet Total suspended solids 504 N N/A


LJ_06 10/24/2017 Wet Total phosphorus 0.01 Y N/A











LJ_01 11/16/2017 Dry Total Kjeldahl nitrogen 0.62 N N/A

LJ_01 11/16/2017 Dry Total phosphorus 0.02 N N/A

LJ_01 11/16/2017 Dry Nitrate + nitrite as N 0.01 Y N/A

LJ_01 11/16/2017 Dry Ammonia as N 0.17 N N/A

LJ_01 11/16/2017 Dry Orthophosphate as P 0.01 Y Possible matrix

interference

LJ_01 11/16/2017 Dry Total suspended solids 1.90 N N/A




A-15




Event Analyte

Result

(mg/L)

Below Level of

Quantitation

(Y/N)

Flag

LJ_02 11/16/2017 Dry Nitrate + nitrite as N 0.01 N N/A


LJ_02 11/16/2017 Dry Orthophosphate as P 0.01 Y N/A


















LJ_05 11/16/2017 Dry Orthophosphate as P 0.01 N N/A








LJ_07 11/16/2017 Dry Total Kjeldahl nitrogen 0.50 Y N/A







A-16




Event Analyte

Result

(mg/L)

Below Level of

Quantitation

(Y/N)

Flag

LJ_08 11/16/2017 Dry Total Kjeldahl nitrogen N/A N/A N/A

LJ_08 11/16/2017 Dry Total phosphorus N/A N/A N/A

LJ_08 11/16/2017 Dry Nitrate + nitrite as N N/A N/A N/A

LJ_08 11/16/2017 Dry Ammonia as N N/A N/A N/A

LJ_08 11/16/2017 Dry Orthophosphate as P N/A N/A N/A

LJ_08 11/16/2017 Dry Total suspended solids N/A N/A N/A


LJ_09 11/16/2017 Dry Total phosphorus 0.01 Y N/A





LJ_Blank 11/16/2017 Dry Total Kjeldahl nitrogen 0.50 Y N/A

LJ_Blank 11/16/2017 Dry Total phosphorus 0.01 Y N/A

LJ_Blank 11/16/2017 Dry Nitrate + nitrite as N 0.01 N N/A

LJ_Blank 11/16/2017 Dry Ammonia as N 0.01 Y N/A

LJ_Blank 11/16/2017 Dry Orthophosphate as P 0.01 Y N/A

LJ_Blank 11/16/2017 Dry Total suspended solids 1.00 Y N/A


A-17


Table A1-4. Results from GreenWater Lab: Algal Properties and Cyanotoxins

Sample ID Sample Date Analyte Result Unit

LJ_02 9/8/2017 Microcystins/nodularins ND µg/L

LJ_02 9/8/2017 Cylindrospermopsin 0.07 µg/L

LJ_02 9/8/2017 Anatoxin-a ND µg/L

LJ_02 9/8/2017 Algal biomass 1.7 mg/L

LJ_02 9/8/2017 Chlorophyll-a 25.6 µg/L

LJ_02 9/8/2017 Chlorophyll-b 0.8 µg/L

LJ_02 9/8/2017 Chlorophyll-c 1.4 µg/L

LJ_02 9/8/2017 Corrected chlorophyll-a 4.4 µg/L

LJ_02 9/8/2017 Pheophytin 34.7 µg/L

LJ_03 9/8/2017 Microcystins/nodularins ND ng/mL

LJ_03 9/8/2017 Cylindrospermopsin 0.11 ng/mL

LJ_03 9/8/2017 Anatoxin-a ND ng/mL




LJ_03 9/8/2017 Chlorophyll-c 0 µg/L


LJ_03 9/8/2017 Pheophytin 25 µg/L


LJ_07 9/8/2017 Cylindrospermopsin ND µg/L








LJ_02 11/16/2017 Microcystins/nodularins ND ng/mL

LJ_02 11/16/2017 Cylindrospermopsin 0.3 ng/mL

LJ_02 11/16/2017 Anatoxin-a ND ng/mL






A-18


Table A1-4. Results from GreenWater Lab: Algal Properties and Cyanotoxins

Sample ID Sample Date Analyte Result Unit




LJ_03 11/16/2017 Cylindrospermopsin 0.33 µg/L




LJ_03 11/16/2017 Chlorophyll-b 0 µg/L

LJ_03 11/16/2017 Chlorophyll-c 0 µg/L




LJ_07 11/16/2017 Cylindrospermopsin ND µg/L



LJ_07 11/16/2017 Chlorophyll-a 4 µg/L

LJ_07 11/16/2017 Chlorophyll-b 1 µg/L





A-19


Table A1-5. Results from GreenWater Lab: Cyanobacteria Composition

Sample

ID Site

Sampling

Date Genus Species

Number

Counted

Counting

Unit

Cells/

Unit

Species

(units/mL)

Species

(cells/mL)

Total Cyano

(units/mL)

Total Cyano

(Cells/mL)

LJ_2-2 2 9/8/2017 55865.384 225036.10

48

LJ_2-2 2 9/8/2017 Merismopedia tenuissima 78 Colony 7 15315.144 107206.0

1

LJ_2-2 2 9/8/2017

Cyanophyte

unicell,

oval/rod

spp. 121 Cell 1 23758.108 23758.10

8

LJ_2-2 2 9/8/2017 Planktolyngbya f. limnetica 5 Filament 18 981.74 17671.32

LJ_2-2 2 9/8/2017 Aphanocapsa delicatissima 9 Colony 9 1767.132 15904.18

8

LJ_2-2 2 9/8/2017 Aphanocapsa sp. 5 Colony 14 981.74 13744.36

LJ_2-2 2 9/8/2017 Cyanophyte cell

pair spp. 33 Colony 2 6479.484

12958.96

8

LJ_2-2 2 9/8/2017 Oscillatorialean

filament sp. 2 Filament 20 392.696 7853.92

LJ_2-2 2 9/8/2017 Aphanothece sp. 4 Colony 10 785.392 7853.92

LJ_2-2 2 9/8/2017 Aphanocapsa conferta 2 Colony 14 392.696 5497.744

LJ_2-2 2 9/8/2017 Cyanophyte tet-

rad spp. 6 Colony 4 1178.088 4712.352

LJ_2-2 2 9/8/2017 Cyanophyte

unicell, sphere spp. 17 Cell 1 3337.916 3337.916




LJ_2-2 2 9/8/2017 Nostocalean fil-

ament sp. 1 2 Filament 14 83.55234

1169.732

8

LJ_2-2 2 9/8/2017 Aphani-

zomenon

flos-aq-

uae/klebahn

ii

10 Filament 15 10 150


A-20



Sample

ID Site

Sampling

Date Genus Species

Number

Counted

Counting

Unit

Cells/

Unit

Species

(units/mL)

Species

(cells/mL)

Total Cyano

(units/mL)

Total Cyano

(Cells/mL)


ament sp. 2 4 Filament 10 4 40

LJ_2-2 2 9/8/2017 Cylindrosper-

mopsis raciborskii 3 Filament 10 3 30

LJ_2-2 2 9/8/2017 Chroococcus minutus 2 Colony 3 2 6

LJ_3-2 3 9/8/2017 64989.268 233513.55

72

LJ_3-2 3 9/8/2017 Merismopedia tenuissima 90 Colony 7 20195.794 141370.5

6

LJ_3-2 3 9/8/2017

Cyanophyte

unicell,

oval/rod

spp. 131 Cell 1 29396.101 29396.10

1



13015.06

7


2


7


4



rad spp. 7 Colony 4 1570.784 6283.136


9


unicell, sphere spp. 18 Cell 1 4039.1589

4039.158

9





584.8663

8


A-21



Sample

ID Site

Sampling

Date Genus Species

Number

Counted

Counting

Unit

Cells/

Unit

Species

(units/mL)

Species

(cells/mL)

Total Cyano

(units/mL)

Total Cyano

(Cells/mL)

LJ_3-2 3 9/8/2017 Chroococcus minutus 1 Colony 3 41.77617 125.3285

1

LJ_3-2 3 9/8/2017 Aphani-

zomenon

flos-aq-

uae/klebahn

ii

7 Filament 15 7 105


mopsis raciborskii 3 Filament 10 3 30


ament sp. 2 3 Filament 10 3 30

LJ_7-2 7 9/8/2017 5253.2054 23558.242

7


rad spp. 25 Colony 4 1308.9867

5235.946

7


LJ_7-2 7 9/8/2017 Pseudana-

baena sp. 4 Filament 18 209.43787

3769.881

6


7



2408.535

5


unicell, sphere spp. 20 Cell 1 1047.1893

1047.189

3

LJ_7-2 7 9/8/2017 cyanophyte uni-

cell, oval/rod spp. 15 Cell 1 785.392 785.392


3


7



colony sp. 1 Colony 10 13.92539 139.2539


A-22



Sample

ID Site

Sampling

Date Genus Species

Number

Counted

Counting

Unit

Cells/

Unit

Species

(units/mL)

Species

(cells/mL)

Total Cyano

(units/mL)

Total Cyano

(Cells/mL)



33.33333

3



23.33333

3



6.666666

7


mopsis raciborskii 1 Filament 10 0.3333333

3.333333

3

LJ_2-2 2 11/16/20

17 1964.3432 20175.867

LJ_2-2 2 11/16/20

17

Aphani-

zomenon

flos-aq-

uae/klebahn

ii

11 Filament 27 345.57248 9330.457

LJ_2-2 2 11/16/20

17

Pseudana-


3204.399

4

LJ_2-2 2 11/16/20

17

Pseudana-


2733.164

2

LJ_2-2 2 11/16/20

17

Nostocalean fil-

ament sp. 7 Filament 25 58.486638 1462.166

LJ_2-2 2 11/16/20

17

Cyanophyte cell


1193.795

8

LJ_2-2 2 11/16/20

17 Planktothrix sp. 1 Filament 86 8.355234

718.5501

3

LJ_2-2 2 11/16/20

17

Cyanophyte

unicell,

oval/rod

spp. 21 Cell 1 659.72928 659.7292

8

LJ_2-2 2 11/16/20

17

Sphaerosper-

mopsis

aphani-

zomenoides 3 Filament 15 25.065702

375.9855

3

LJ_2-2 2 11/16/20

17 Merismopedia tenuissima 1 Colony 21 8.355234

175.4599

1

LJ_2-2 2 11/16/20

17

Dolichosper-

mum sp. 1 Filament 15 8.355234

125.3285

1


A-23



Sample

ID Site

Sampling

Date Genus Species

Number

Counted

Counting

Unit

Cells/

Unit

Species

(units/mL)

Species

(cells/mL)

Total Cyano

(units/mL)

Total Cyano

(Cells/mL)

LJ_2-2 2 11/16/20

17 Aphanocapsa sp. 1 Colony 400 0.2 80

LJ_2-2 2 11/16/20

17

Cyanophyte


LJ_2-2 2 11/16/20

17

Dolichosper-

mum

cf. planctoni-

cum 10 Filament 27 2 54

LJ_3-2 3 11/16/20

17 1713.8177

11200.517

26

LJ_3-2 3 11/16/20

17

Aphani-

zomenon

flos-aq-

uae/klebahn

ii

7 Filament 26 219.90976 5717.653

8

LJ_3-2 3 11/16/20

17

Cyanophyte cell


1256.627

2

LJ_3-2 3 11/16/20

17

Nostocalean fil-

ament sp. 8 Filament 16 66.841872 1069.47

LJ_3-2 3 11/16/20

17

Pseudana-


973.8860

8

LJ_3-2 3 11/16/20

17

Cyanophyte

unicell,

oval/rod

spp. 21 Cell 1 659.72928 659.7292

8

LJ_3-2 3 11/16/20

17

Pseudana-


502.6508

8

LJ_3-2 3 11/16/20

17

Sphaerosper-

mopsis

aphani-

zomenoides 3 Filament 19 25.065702

476.2483

4

LJ_3-2 3 11/16/20

17 Planktothrix sp. 10 Filament 120 2 240

LJ_3-2 3 11/16/20

17

Dolichosper-

mum sp. 2 Filament 13 16.710468

217.2360

9

LJ_3-2 3 11/16/20

17 Aphanocapsa incerta 1 Colony 200 0.2 40

LJ_3-2 3 11/16/20

17

Cyanophyte



A-24



Sample

ID Site

Sampling

Date Genus Species

Number

Counted

Counting

Unit

Cells/

Unit

Species

(units/mL)

Species

(cells/mL)

Total Cyano

(units/mL)

Total Cyano

(Cells/mL)

LJ_3-2 3 11/16/20

17

Dolichosper-

mum

cf. planctoni-

cum 2 Filament 16 0.4 6.4

LJ_3-2 3 11/16/20

17 Merismopedia sp. 1 Colony 31 0.2 6.2

LJ_3-2 3 11/16/20

17

cf. Dolichosper-

mum sp. 1 Filament 15 0.2 3

LJ_7-2 7 11/16/20

17 109.36804

1152.2131

66

LJ_7-2 7 11/16/20

17 Aphanocapsa incerta 2 Colony 17 39.2696 667.5832

LJ_7-2 7 11/16/20

17 Aphanocapsa conferta 1 Colony 12 19.6348 235.6176

LJ_7-2 7 11/16/20

17 Planktolyngbya f. limnetica 2 Filament 18 10.444043

187.9927

7

LJ_7-2 7 11/16/20

17

Cyanophyte

unicell,

oval/rod

spp. 2 Cell 1 39.2696 39.2696

LJ_7-2 7 11/16/20

17 Cuspidothrix

issatschen-

koi 6 Filament 29 0.75 21.75


B-1


Attachment B: Technical Memorandum on May 2017

Sampling


301 Bendix Road

Virginia Beach, VA 23452

T: 757.518.2400

F: 757.518.2401

Prepared for: City of Virginia Beach

Project Title: Work Order 18, Task 3 - Lake James Near Term Sampling

Project No.: 150503.003


Subject: May 2017 Lake James Water Quality Sampling

Date: June 22, 2017

To: Tara Gallagher and David Hostetler, City of Virginia Beach

From: Mira Micin and Clifton Bell, Brown and Caldwell

Copy to: Melanie Coffey, City of Virginia Beach

Stephanie Hanses, Brown and Caldwell

May 2017 Lake James Water Quality Sampling

1

Use of contents on this sheet is subject to the limitations specified at the beginning of this document.

WO18 T1 Lake James Near Term Sampling 06 13 2017.docx

Section 1: Introduction

In response to citizen concerns to water quality in Lake James, the City of Virginia Beach (City) has initiated a

monitoring study of the lake and its drainage area. The study will include five monitoring events in 2017.

This technical memo provides the results of the first sampling event, conducted on May 17, 2017. During

this event, the field team sampled at eight locations within the Lake James watershed. Two locations were

within the lake, four locations were in the Cedar Hill Canal, and two locations were in channels that connect

the Cedar Hill canal with Lake James. This technical memorandum describes the sampling methodologies,

conditions during the field visit, sampling parameters, site locations, results summary, and a limited interpre-

tation of the sampling results. More complete interpretations of these data will be provided at the comple-

tion of the full monitoring study.

Section 2: Methods

Field sampling was conducted on the morning of May 17 in the Lake James watershed. The weather was

partly cloudy and 68◦F with no antecedent rainfall for more than 72 hours before the field visit. At each of

the eight sample locations, basic water quality parameters (pH, dissolved oxygen, water temperature, and

specific conductance) were measured used YSI 556 MPS 556-02 multiparameter instrument that was cali-

brated prior to use. Turbidity was measured with a LaMotte 2020we turbidity meter.

Grab samples were collected at each location using sterile laboratory-supplied sample bottles with appropri-

ate preservatives. Water quality samples were placed on ice and delivered to the Hampton Roads Sanitation

District (HRSD) for analysis of the following constituents:

Ammonia

Nitrate-plus-nitrate

Total Kjeldahl nitrogen

Total phosphorus

Orthophosphorus

Total suspended solids

Samples for algal analysis were shipped on ice packs by express courier to the GreenWater Laboratory in

Florida.

Microcystin-LR

Cylindrospermopsin

Anatoxin-a

Cyanobacteria species identification and enumeration

All sites were sampled for basic water quality parameters and nutrient concentrations. Only the lake samples

(locations 2 and 3) were analyzed for algal toxins and algal/cyanobacteria species composition.

Figure 1 documents the eight sample locations. A description of the locations are as follows:

Site 1 – Located in the southern channel that connects the Cedar Hill Canal with Lake James, near

the weir at the outlet. At the time of sampling, there was flow leaving the lake into the canal.


2



Site 2 – Located on the lake side of the outlet weir in Lake James.

Site 3 – Located on the lake side of the inlet weir in Lake James. No visible inflow from the weir was

observed at the time of sampling.

Site 4 – Located in the northern channel that connects Cedar Hill Canal with Lake James, on the ca-

nal side of the weir. A sheen was observed on the water surface.

Site 5 – Located at the entrance to the Hampton Roads Reclamation Center (HRRC) at the most up-

stream portion of the Cedar Hill Canal.

Site 6 – Located in the Cedar Hill Canal near the discharge pipe from the HRRC groundwater pump-

ing upstream of Lake James. At the time of sampling, there was no flow from the pipe.

Site 7 – Located in the Cedar Hill Canal adjacent to the Brandon Middle School field upstream of

Lake James. A sheen was observed on the water surface.

Site 8 – Located in the Cedar Hill Canal downstream of Jake James at New Light Baptist Church on

the corner of Indian River Road and Centerville Turnpike.

Photos of sampling sites are included in Appendix A.


3



Figure 1 - Sampling Locations

Section 3: Sample Results

Sample results for basic water quality parameters, nutrient concentrations, algal toxin analysis, and cyano-

bacteria enumeration are included in this section. Table 3-1 summarized the results of the field and labora-

tory analyses.


4



Table 3-1. Results of May 2017 Sampling Event

Parameters

Site

1 2 3 4 5 6 7 8

pH (s.u.) 7.0 8.37 7.83 7.41 8.03 7.83 7.49 7.28

Dissolved Oxygen (mg/L) 4.13 7.52 5.53 2.70 5.20 5.70 2.94 3.03

Temperature (deg C) 20.8 21.9 21.8 20.5 24.2 23.2 22.2 25.1

Specific Conductance (µS/cm) 0.770 0.317 0.316 1.305 2.065 1.574 1.075 0.809

Turbidity (NTU) 12.7 7.39 4.95 21.8 99.8 29.1 46.0 18.8

Ammonia nitrogen (mg/L as N) 0.45 0.03 0.10 3.18 0.14 5.03 3.25 1.62

Nitrate-plus-nitrate nitrogen (mg/L) 0.14 <0.01 0.09 0.52 <0.01 0.45 0.53 0.20

Total Kjeldahl Nitrogen (mg/L) 1.10 0.99 0.72 3.94 4.78 5.85 3.80 2.25

Total Phosphorus (mg/L) 0.03 0.03 0.03 0.13 0.66 0.09 0.12 0.10

Orthophosphorus (mg/L as P) 0.01 0.02 <0.01 0.01 0.01 0.01 0.01 0.02

Total Suspended Solids (mg/L) 7.9 9.8 4.6 113 674 104 121 17.7

Anatoxin-a (µg/L) -- ND1 ND1 -- -- -- -- --

Cylindrospermopsin (µg/L) -- 0.12 0.09 -- -- -- -- --

Microcystin-LR (µg/L) -- 4.70 0.03 -- -- -- -- --

Cyanobacteria species Aphanizomenon flos-aquae/klebahnii (cells/mL)

-- 167,446 73,120 -- -- -- -- --

Cyanobacteria species Planktothrix agardhii (cells/mL)

-- 58,904 2,757 -- -- -- -- --

Cyanobacteria species Aphanothece sp. (cells/mL)

-- 2,513 -- -- -- -- -- --

Cyanobacteria species

Aphanocapsa sp. (cells/mL) -- 2,199 -- -- -- -- -- --


oscillatorialean filament sp. (cells/mL) -- -- 707 -- -- -- -- --


Geitlerinema/Jaaginema sp. (cells/mL) -- -- 627 -- -- -- -- --


Pseudanabaena sp. (cells/mL) -- -- 471 -- -- -- -- --


cyanophyte cell pair spp. (cells/mL) -- -- 314 -- -- -- -- --

Cyanobacteria species cyanophyte uni-cell, oval/rod spp. (cells/mL)

-- -- 157 -- -- -- -- --

1Not detected above the method detection limit. The Method Detection Limit for Microcystin is 0.15, Cylndrespermopsin is 0.09, and Anatoxin-a

is 0.03.


5



Section 4: Initial Observations

A full evaluation of the water quality monitoring data will be deferred until the completion of the 2017 Lake

James monitoring study, which will include collection of additional samples under dry-weather and wet-

weather conditions. Future monitoring will incorporate additional components and analysis including moni-

toring of lake water quality profiles in mid-lake locations, analysis of chlorophyll-a, sampling of Lake Christo-

pher, and a more detailed examination of the effects of the HRRC discharge on the canal water quality. Fol-

lowing are some initial observations from the data collected in May 2017:

There was a significant increase in ammonia concentrations between the upstream-most site on the

canal (site 5) and the site near the HRRC discharge (site 6). Ammonia concentrations increased from

0.14 mg/L to 5.03 mg/L between these two locations. Ammonia concentrations decreased down-

stream of site 6, but remain elevated throughout the canal.

TSS was also relatively high (>100 mg/L) in the canal, even upstream of the HRRC discharge. TSS

was much lower in the lake and in the canal, downstream of the lake.

Although total phosphorus concentrations were higher in the canal than the lake, bioavailable phos-

phorus (as measured by orthophosphorus) was relatively low in the canal: ~0.01 mg/L in most sam-

ples.

The lake results (sites 2 & 3) provide mixed results regarding whether N or P would limit algae

growth, as inferred from ratios of dissolved inorganic nitrogen (nitrate+nitrite+ammonia) to ortho-

phosphorus. Site 2 ratios suggest N-limitation, whereas site 3 ratios suggest P limitation. Some dis-

solved organic nitrogen might also be bioavailable. The potential for nutrient limitations will be evalu-

ated at the end of the study.

Regarding algal toxins in the two lake samples:

• Anatoxin-a was not detected in either sample.

• Cylindrospermopsin was detected but did not exceed EPA’s draft recreational guideline of

(8 ug/L).

• Microcystin was detected but did not exceed Virginia’s recreational advisory threshold (6

ug/L).

Regarding cyanobacteria counts in the two lake samples:

• The most abundant cyanophyte in both samples was Aphanizomenon flos-aq-

uae/klebahnii, a nitrogen-fixing taxon which is capable of producing cyanotoxins. • The second-most abundant taxon was Planktothrix agardhii, which is also capable of pro-

ducing cyanotoxins. • The total cyanobacteria abundance in samples [Site 2 and Site 3] were 231,062 and

78,153 cells/mL, respectively. For reference, the World Health Organization cites cyano-

bacteria abundance of 20,000 – 100,000 cells/mL as representing a “moderate” health

risk for full contact recreation, and values greater than 100,000 cell/mL as representing

a “high” risk. • The actual risk would depend more directly on the concentrations of cyanotoxins present,

rather than the cell count.


A-1



Attachment A: Sample Locations

Site visit was conducted on May 17, 2017.


A-2



Figure A-1 - Site 1


A-3



Figure A-2 - Site 2


A-4



Figure A-3 - Site 3


A-5



Figure A-4 - Site 4


A-6



Figure A-5 - Site 6


A-7



Figure A-6 - Site 7


A-8



Figure A-7 - Site 8


B-2



Documents

Technical Memorandum - VBgov.com