Technical Memorandum. 301 Bendix Road, Suite 400 Virginia Beach, VA T: F:

Transcription

1 301 Bendix Road, Suite 400 Virginia Beach, VA Technical Memorandum T: F: Prepared for: The City of Virginia Beach Department of Public Works Project title: Lake James Water Quality Monitoring and Evaluation Project no.: Technical Memorandum 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

2 Table of Contents Executive Summary... 1 Section 1: Introduction Description of Study Area Summary of Previous Monitoring... 3 Section 2: Methods Sampling Locations Sampling Dates and Conditions Field Methods Laboratory Methods... 6 Section 3: Results Field Parameters Lake Profiles Spatial Patterns Nitrogen Phosphorus Total Suspended Solids Chlorophyll-a and Algae Section 4: Discussion General Factors Affecting Cyanobacterial Blooms Potential Nutrient Limitations in Lake James Conceptual Model of Lake James Section 5: Conclusions and Recommendations References Attachment A: Water Quality Monitoring Data... A-1 Attachment B: Technical Memorandum on May 2017 Sampling... B-1 ii

3 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) Figure 6. Map of spatial patterns of temperature in Cedar Hill Canal during the probe-based survey (11/6/2017) 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 Figure 9. Map of spatial patterns of ph in Cedar Hill Canal during the probe-based survey (11/6/2017) Figure 10. Longitudinal pattern of ph in Cedar Hill Canal from upstream to downstream during the probebased 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 Figure 12. Map of spatial patterns of specific conductance in Cedar Hill Canal during the probe-based survey (11/6/ 2017) 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 Figure 15. Map of spatial patterns of dissolved oxygen in Cedar Hill Canal during the probe-based survey (11/6/2017) 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 Figure 18. Graph of ammonia concentrations in Cedar Hill Canal during the probe-based survey (11/6/2017) 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 iii

4 Figure 21. Graph of nitrate and nitrite 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 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 Figure 23. Graph of total phosphorus 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 Figure 24. Graph of orthophosphate 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 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 Figure 26. Graph of corrected chlorophyll-a during the dry weather sampling events (September November 2017) 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 Table 5. Cyanobacteria Density (cells/ml) in Lake James and Lake Christopher Table 6. Cyanotoxin Concentrations (ug/l) in Lake James and Lake Christopher Table 7. Dissolved Inorganic Nitrogen: Orthophosphate Molar Ratios from Synoptic Sampling Events 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 iv

5 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 LF mg ml ms N ng P s.u. TKN TM TSS VDH WHO liter(s) landfill milligram(s) milliliter(s) millisiemens nitrogen nanogram(s) phosphorus standard unit(s) total Kjeldahl nitrogen technical memorandum total suspended solids Virginia Department of Health World Health Organization v

6 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 technical 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 various 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 Cedar 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 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. 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 expected 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 evaluation of nitrogen (N)-to-phosphorus (P) ratios revealed that Lake James can experience either phosphorus 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 dominant during different bloom events. 4. Lake James has characteristics unrelated to the canal inputs that probably favor periodic cyanobacteria 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 sustaining 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. 1

7 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 discharge appears to be complying with its effluent permit limits and was not observed to cause exceedances of Virginia s water quality criterion for ammonia. Given the importance of Lake James for stormwater 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 discharge 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 improved. 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 failures 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 waters in 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 includes more than 270 homes, over 100 of which are on the lakefront. The maximum lake depth is approximately 40 feet (Bass and Schafran 2009). Although residents sometimes use the lake for boating, gas motors 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, 2

8 Lake James discharges to the canal via these same connecting channels. Lake James receives an undetermined 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 algal levels increased during the years leading up to 2009, prompting the homeowners to sponsor a monitoring 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, prompting 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 interpretations 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 millisiemens per centimeter (ms/cm) range in Lake James, compared with 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 Cedar 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 Virginia 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 entering the lake. The Virginia Department of Environmental Quality (DEQ) sampled Lake James during the cyanobacterial bloom of February 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 3

9 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 locations on Lake James and the Cedar Hill Canal in May These sampling results confirm elevated measurements of several water quality parameters in the Cedar Hill Canal, most notably specific conductance ( ms/cm) and ammonia-n ( 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 mg/l. The bioavailable form of phosphorus (orthophosphorus) was relatively low ( 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 cyanobacterial 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 microcystin-lr was detected at 4.7 µg/l, which was below but close to VDH s advisory threshold (6 µg/l). The cyanobacteria 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 between August and December 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 performed 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 southern weir, respectively. Site 4 is located in the Cedar Hill Canal at the outfall that drains the HRRC. This sample 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 sampling events, the field crew sampled the pumped water at Site 8. This occurred once during the wet weather event conducted on September 14, 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 Cedar Hill Canal, this site was sampled to support evaluations of whether the HRRC discharge could be diverted to the pond. 4

10 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 5

11 2.3 Field Methods At each sampling site, the field crew used a YSI multimeter probe to measure temperature, ph, specific conductance, 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 suspended 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 information 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. Additionally, 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 laboratory bottle (with no preservative) to fill the smaller laboratory bottles. These bottles were sterilized in the laboratory; no DI rinse was required. For the in-lake sites, samples were also collected and shipped for analysis 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 Canal. 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 multimeter probe. No grab samples were collected for this portion of the study. Probes were calibrated on the morning of the survey and rinsed with DI water prior to taking measurements. Investigators recorded measurements 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. 6

12 Section 3: Results Table 2. Laboratory Analysis Methods Analyte Method Analyte Method Ammonia EPA Algal biomass SM H Nitrate and nitrite EPA TKN EPA Chlorophyll-a, -b, -c SM H SM H Orthophosphate EPA Pheophytin SM H Total phosphorus EPA Anatoxin-a EPA 545 TSS SM 2540 D-2011 Microcystins and nodularins Corrected chlorophyll-a Cylindrospermopsin EPA 546 EPA 545 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 patterns 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 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 experiencing 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. 7

13 Height of Measurement (ft) Height of Measurement (ft) 2017 Water Quality Monitoring of Lake James and Nearby Waters 0 Temperature ( C) Site 2- Warm Site 2- Cool Site 3- Warm Site 3- Cool Site 7- Warm Site 7- Cool 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 photosynthesis 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 criterion for ph (6 9 standard units [s.u.]). ph Site 2- Warm Site 2- Cool Site 3- Warm Site 3- Cool Site 7- Warm Site 7- Cool Figure 3. Graph of ph profile in Lake James (Sites 2 and 3) and Lake Christopher (Site 7) 8

14 Height of Measurement (ft) 2017 Water Quality Monitoring of Lake James and Nearby Waters As seen in Figure 4, specific conductance was higher in Lake James than in Lake Christopher. Specific conductance 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. 0 Specific Conductance (ms/cm) Site 2- Warm Site 2- Cool Site 3- Warm Site 3- Cool Site 7- Warm Site 7- Cool 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 Christopher. 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 criterion of 4.0 mg/l in either Lake James or Lake Christopher. 9

15 Height of Measurement (ft) 2017 Water Quality Monitoring of Lake James and Nearby Waters 0 Dissolved Oxygen (mg/l) Site 2- Warm Site 2- Cool Site 3- Warm Site 3- Cool Site 7- Warm Site 7- Cool Figure 5. Graph of dissolved oxygen profile in Lake James (Sites 2 and 3) and Lake Christopher (Site 7) 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 shallower 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). 10

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

17 Temperature ( C) Temperature ( C) 2017 Water Quality Monitoring of Lake James and Nearby Waters Sequence ID Figure 7. Longitudinal profile of temperature in Cedar Hill Canal from upstream to downstream during the probebased survey (11/6/2017) 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 Dry- Warm Wet- Warm Dry - Cool Wet - Cool 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 12

18 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 surface water (USGS 2016). ph was also within the expected range during the synoptic sampling events, excluding 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 algae growth in the canal. Figure 9. Map of spatial patterns of ph in Cedar Hill Canal during the probe-based survey (11/6/2017) 13

19 ph ph 2017 Water Quality Monitoring of Lake James and Nearby Waters Sequence ID Figure 10. Longitudinal pattern of ph in Cedar Hill Canal from upstream to downstream during the probe-based survey (11/6/2017) 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 Dry- Warm Wet- Warm Dry - Cool Wet - Cool 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. 14

20 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 to ms/cm (Hem 1989), ocean water is typically 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 accumulates 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) 15

21 Specific Conductance (ms/cm) Specific Conductance (ms/cm) 2017 Water Quality Monitoring of Lake James and Nearby Waters Sequence ID Figure 13. Longitudinal profile of specific conductance in Cedar Hill Canal from upstream to downstream during the probe-based survey (11/6/2017) 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 Dry- Warm Wet- Warm Dry - Cool Wet - Cool 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. 16

22 Figure 15 displays the DO results from the canal survey. Unlike other parameters studied, DO had no obvious 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 canal; 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 concentrations 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) 17

23 Dissolved Oxygen (mg/l) Dissolved Oxygen (mg/l) 2017 Water Quality Monitoring of Lake James and Nearby Waters Sequence ID Figure 16. Longitudinal profile of dissolved oxygen in Cedar Hill Canal from upstream to downstream during the probe-based survey (11/6/2017) 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 Dry- Warm Wet- Warm Dry - Cool Wet - Cool 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. 18

24 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 represents the water draining directly from the HRRC pond (Site 4). This point had the highest ammonia concentrations 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 ( mg/l as N). Based on the synoptic survey grab sample data, ammonia concentrations were not consistently different between 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 criteria is expressed as a 30-day average value, and so should not be evaluated in individual grab samples. However, the 2017 results demonstrate the potential for exceedance of the chronic ammonia criteria in the canal 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). 19

25 Figure 18. Graph of ammonia concentrations in Cedar Hill Canal during the probe-based survey (11/6/2017) 20

26 Ammonia (mg/l as N) Ammonia (mg/l as N) 2017 Water Quality Monitoring of Lake James and Nearby Waters Sequence ID Figure 19. Graph of ammonia-n concentrations in Cedar Hill Canal from upstream to downstream during the probebased survey (11/6/2017) 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 Dry-Warm Wet-Warm Dry-Cool Wet-Cool 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. 21

27 Table 3. Comparison of Ammonia Concentrations to State and Federal Water Quality Criteria Virginia EPA 2013 Virginia Measured Chronic Chronic Acute Location Site Date Ammonia Criterion Criterion Criterion (mg/l as N) (mg/l as N) (mg/l as N) (mg/l as N) Cedar Hill Canal Lake James Lake Chris. LF Pond LF Pond = Landfill pond EPA 2013 Acute Criterion (mg/l as N) Site 4 9/8/ Site 5 9/8/ Site 4 9/14/ Site 5 9/14/ Site 8 9/14/ Site 4 10/24/ Site 4 11/16/ Site 5 11/16/ Site 1 9/8/ Site 2 9/8/ Site 3 9/8/ Site 6 9/8/ Site 1 9/14/ Site 6 9/14/ Site 1 10/24/ Site 6 10/24/ Site 1 11/16/ Site 2 11/16/ Site 3 11/16/ Site 6 11/16/ Site 7 9/8/ Site 7 11/16/ Site 9 9/8/ Site 9 9/14/ Site 9 10/24/ Site 9 11/16/ 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 sample data, significant differences were not found between site, season, or weather event. However, on average 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 groundwater was actively being pumped. Concentrations were not significantly different between Lake James and Lake Christopher. 22

28 Nitrite and Nitrate (mg/l as N) 2017 Water Quality Monitoring of Lake James and Nearby Waters 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 < < < < < < < < < < < < < 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 Dry-Warm Wet-Warm Dry-Cool Wet-Cool Figure 21. Graph of nitrite and nitrate 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 (0.01 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. 23

29 Total Kjeldahl Nitrogen (mg/l) 2017 Water Quality Monitoring of Lake James and Nearby Waters < < < < < < < 0.10 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 Dry-Warm Wet-Warm Dry-Cool Wet-Cool 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. 24

30 Total Phosphorus (mg/l) 2017 Water Quality Monitoring of Lake James and Nearby Waters < < < < < 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 Dry-Warm Wet-Warm Dry-Cool Wet-Cool Figure 23. Graph of total phosphorus 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 (0.01 mg/l). LF = landfill. Orthophosphate concentrations were found to be relatively low ( 0.06 mg/l as P) at all sites and in all seasons (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 concentrations were below 0.04 mg/l as P. As with total phosphorus, both Sites 4 and 8 had very similar orthophosphate concentrations. Based on the low orthophosphate concentrations, most of the total phosphorus was probably in organic or particulate, non-bioavailable forms. 25

31 Orthophosphate (mg/l as P) 2017 Water Quality Monitoring of Lake James and Nearby Waters < < < < < < < < < 0.00 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 Dry-Warm Wet-Warm Dry-Cool Wet-Cool Figure 24. Graph of orthophosphate 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 (0.01 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 sediments during the warm, dry season as well as the cool, wet season (Figure 25). Because of the shallow nature of these sites, TSS concentrations might have been affected by resuspension from the bottom. In contrast to other parameters, Site 8 showed higher concentrations of TSS than Site 4 when HRRC was actively pumping. 26

32 Total Suspended Solids (mg/l) 2017 Water Quality Monitoring of Lake James and Nearby Waters 10, , < < 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 Dry-Warm Wet-Warm Dry-Cool Wet-Cool 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. Bars with < above them represent concentrations below the limit of quantification (1.0 mg/l). LF = landfill. 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 between 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 Cool

33 Corrected Chlorophyll-a (ug/l) 2017 Water Quality Monitoring of Lake James and Nearby Waters Site 2 Site 3 Site 7 Lake James Lake Christopher Warm Cool 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 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 cyanobacteria population are dominated by potential toxin formers. In contrast, VDH uses thresholds based on a single potentially toxigenic cyanobacteria taxon (Microcystis) rather than total cyanobacteria. Specifically, VDH recommends that local health districts and environmental agencies should be alerted when Microcystis densities become greater than 5,000 cells/ml, and that the public should be notified for concentrations greater than 20,000 cells/ml. Season Warm Cool Table 5. Cyanobacteria Density (cells/ml) in Lake James and Lake Christopher Analyte Site 2 (Lake James) Site 3 (Lake James) Site 7 (Lake Christopher) Total 225, ,514 23,558 Potentially toxigenic 1, ,836 Total 20,176 11,201 1,152 Potentially toxigenic 18,003 9,

34 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 suggest 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 occurred 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 cyanotoxins 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 Cool Section 4: Discussion Cylindrospermopsin <0.05 Microcystins/nodularins <0.15 <0.15 <0.15 Anatoxin-a <0.05 <0.05 <0.05 Cylindrospermopsin <0.05 Microcystins/nodularins <0.15 <0.15 <0.15 Anatoxin-a <0.05 <0.05 <0.05 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 (Section 4.2). Finally, a conceptual model of the lake algae dynamics is presented in Section General Factors Affecting Cyanobacterial Blooms General factors that affect cyanobacterial blooms are relevant to this investigation because an understanding 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 Virginia 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 29

35 dramatic changes in environmental conditions make it easier for aggressive primary colonizing cyanobacteria 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 typically 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 conditions (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 availability 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 Aphanizomenon flos-aquae have been shown to increase biomass in winter when populations of other phytoplankton 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 because of seasonal nutrient shifts (Teubner et al. 1999). The discussion above illustrates the array of physiological mechanisms, very broad tolerances, and adaptability 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 substantial 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 areas 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 phosphorus-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 nitrogen 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 30

36 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 censored (> 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 prevail. Table 7. Dissolved Inorganic Nitrogen: Orthophosphate Molar Ratios from Synoptic Sampling Events Weather Event Lake James Canal Lake Chris. 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: 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 conditions often dictates which species will dominate during blooms (Teubner et al. 1999). During times when nitrogen is limiting and phosphorus is abundant, species of nitrogen-fixing cyanobacteria, such as Aphanizomenon 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 biomass 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 portion of the lake may have a longer retention time than the water near the inlet/outlet channels. High retention times provide longer periods for algae to use the available nutrients, and lower rates of flushing of the algae that is produced. 31

37 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 sediments, 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 available 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 diatoms. Lake turnover can also resuspend dormant cyanobacterial algal cells from the lake bottom, allowing 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 temperature tolerance and may also be taking advantage of nutrients from waters that are isolated from the surface by thermal stratification during the warmer months. Nutrient and sediment inputs from the watershed and the Cedar Hill Canal: The monitoring results presented 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 monitoring 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 connection. 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 sediments that can sometimes be re-mobilized to support algal growth even when the canal is not actively flowing 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. 32

38 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 nitrogen 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 fixers 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. Information is currently insufficient to quantify the proportion of nutrient inputs to Lake James that are derived 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 potential contributor to algal blooms in Lake James. Given the importance of Lake James for stormwater management 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 33

39 will consist primarily of stormwater runoff routed through a retention basin yet to be built (personal communication, Charles Plott, HRRC, November 30, 2017). The quality of the discharge to the Cedar Hill Canal 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 improved. For this reason, algacide treatments may continue to sometimes be necessary. It should be emphasized 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 recreation 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 depend upon the sediment phosphorus content and the relative magnitude of this nutrient source compared 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 management methods of uncertain effectiveness. 34

40 References Bass, L. and Schafran, G 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, Ammonium nitrogen: A key regulatory factor causing dominance of nonnitrogen-fixing cyanobacteria in aquatic systems. Arch. Hydrobiol. 132: 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, p. Chorus, I., and Bartram, J 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 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 Paper 2254, 1989, 263 p. Holmroos, H., Horppila, J., Laakso, S., Niemisto, J., and Hietanen, S Aeration-Induced Changes in Temperature and Nitrogen Dynamics in a Dimictic Lake. J Environ Qual Jul;45(4): Huisman J., Sharples J., Stroom J.M., Visser P.M., Kardinaal W.E.A., Verspagen J.M.H., Sommeijer B Changes in turbulent mixing shift competition for light between phytoplankton species. Ecology 85: Malcolm Pirnie 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 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 Phytoplankton in Virginia Lakes and Reservoirs. Virginia Journal of Science, 64 (1-1), Pearl, H.W. and T.G. Otten, Harmful Cyanobacterial Blooms: Causes, Consequences, and Controls, Microb. Ecol., May 2013, Volume 65, Issue p. Rolland, D.C., Bourget, S., Warren, A., Laurion, I., and Vincent, W Extreme variability of cyanbacterial blooms in an urban drinking water supply. Journal of Plankton Research 35(4): Romo, S., Soria, J., Fernandez, F., Oauhid, Y., and Baron-Sola, A Water residence time and the dynamics of toxic cyanobacteria. Freshwater Biology 58 (3): 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 flowaquae 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, p. Thomann, R.V., and Mueller, J.A Principles of Surface Water Quality Modeling and Control. Harper and Row Publishers, New York, N.Y. 644 p. U.S. Geological Survey (USGS) ph- Water Properties, (December 19, 2017) Visser, P.M., Ibelings, B.W., Bormans, M., and Huisman, J Artificial mixing to control cyanobacterial blooms: a review. Aquatic Ecology 50(3): Yamamoto, Y., Environmental factors that determine the occurrence and seasonal dynamics of Aphanizomenon flos-aquae, Journal of Limnology, February 2009, Volume 68, Issue 1, p. 35

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42 Attachment A: Water Quality Monitoring Data A-1

43 This page left blank intentionally. A-2

44 Weather Event Site Date Time Table A1-1. Raw Data Measured at Shore Adjacent Sites Specific Dissolved Temperature ( C) ance (NTU) Conduct- Turbidity ph Oxygen (mg/l) (ms/cm) Dry 1 9/8/ : Dry 4 9/8/ : ,671++ Dry 5 9/8/ : Dry 6 9/8/ : No comments Comments Several ducks and turtles observed at time of sampling. Duplicate sample collected at Site 1. Notably more turbid than Site 5. Very shallow, muddy water. Shallow water, unable to avoid disturbing bottom during sampling. 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: Sample taken where pump hose leads into the water. Wet 1 9/14/ : No comments Wet 4 9/14/ : No comments Wet 5 9/14/ : Canal was dry directly before the outfall, sampled ~800 ft upstream at the first area with standing water. Wet 6 9/14/ : No comments Wet 8 9/14/ : Wet 9 9/14/ : No comments Wet 1 10/24/2017 8: No comments Wet 4 10/24/2017 9: No comments Heavy flow at time of sampling. Collected sample directly from outflow. Wet 5 10/24/2017 NA NA NA NA NA NA Canal had no standing water. Wet 6 10/24/2017 8: No comments Wet 8 10/24/2017 NA NA NA NA NA NA No water being pumped during visit. Next closest sampling point was at Site 4. A-3

45 Weather Event Site Date Time Table A1-1. Raw Data Measured at Shore Adjacent Sites Specific Dissolved Temperature ( C) ance (NTU) Conduct- Turbidity ph Oxygen (mg/l) (ms/cm) Wet 9 10/24/2017 9: No comments Comments Dry 1 11/16/ : NR No comments Dry 4 11/16/ : NR Noticeably clearer than any other visit. Small fish could be seen in the ponded water. Dry 5 11/16/ : NR Construction had recently been done at the outfall. Small pools of water were present near the sampling point but further upstream was too shallow (where water was pooling) to sample. Dry 6 11/16/ : NR No comments Dry 8 11/16/2017 NA NA NA NA NA NA No water being pumped during visit. Next closest sampling point was at Site 4. Dry 9 11/16/ : NR No comments A-4

46 Site Date Time Depth 2 9/8/ :10 Site/Depth ID Table A1-2. Raw Data Measured at In-Lake Sites Specific Temperature ( C) ance Conduct- ph (ms/cm) Dissolved Oxygen (mg/l) Turbidity (NTU) 2_ No comment 2 9/8/ :10-3 ft 2_ No comment 2 9/8/ :10-6 ft 2_ No comment 2 9/8/ :10-9 ft 2_ No comment 2 9/8/ :10-12 ft 2_ No comment 2 9/8/ :10-15 ft 2_ No comment 2 9/8/ :10-18 ft 2_ No comment 2 9/8/ :10-21 ft 2_ No comment 2 9/8/ :10-24 ft 2_ No comment 2 9/8/ :10-27 ft 2_ No comment 2 9/8/ :10-30 ft 2_ No comment 2 9/8/ :10-33 ft 2_ NA No comment 2 9/8/ :10-36 ft 2_ NA No comment 2 9/8/ :10-39 ft 2_ NA No comment Surface 2 9/8/ :10-42 ft 2_ NA No comment 3 9/8/ :45 Surface 3_ No comment 3 9/8/ :45-3 ft 3_ No comment 3 9/8/ :45-6 ft 3_ No comment 3 9/8/ :45-9 ft 3_ No comment 3 9/8/ :45-12 ft 3_ No comment 3 9/8/ :45-15 ft 3_ No comment Comments A-5

47 Site Date Time Depth Site/Depth ID Table A1-2. Raw Data Measured at In-Lake Sites Specific Temperature ( C) ance Conduct- ph (ms/cm) Dissolved Oxygen (mg/l) Turbidity (NTU) 3 9/8/ :45-18 ft 3_ No comment 3 9/8/ :45-21 ft 3_ No comment 3 9/8/ :45-24 ft 3_ No comment 3 9/8/ :45-27 ft 3_ No comment 3 9/8/ :45-30 ft 3_ NA No comment 3 9/8/ :45-33 ft 3_ NA No comment 3 9/8/ :45-36 ft 3_ NA No comment 3 9/8/ :45-39 ft 3_ NA No comment 7 9/8/ :20 Surface 7_ No comment 7 9/8/ :20-3 ft 7_ No comment 7 9/8/ :20-6 ft 7_ No comment 7 9/8/ :20-9 ft 7_ No comment 7 9/8/ :20-12 ft 7_ No comment 7 9/8/ :20-15 ft 7_ No comment 7 9/8/ :20-18 ft 7_ No comment 7 9/8/ :20-21 ft 7_ No comment 7 9/8/ :20-24 ft 7_ No comment 7 9/8/ :20-27 ft 7_ No comment 7 9/8/ :20-30 ft 7_ NA No comment 7 9/8/ :20-33 ft 7_ NA No comment 7 9/8/ :20-36 ft 7_ NA No comment Comments A-6

48 Site Date Time Depth 2 11/16/ :21 Surface Site/Depth ID Table A1-2. Raw Data Measured at In-Lake Sites Specific Temperature ( C) ance Conduct- ph (ms/cm) Dissolved Oxygen (mg/l) Turbidity (NTU) 2_ NA 2 11/16/ :22-3 ft 2_ NA No comment 2 11/16/ :23-6 ft 2_ NA No comment 2 11/16/ :24-9 ft 2_ NA No comment 2 11/16/ :24-12 ft 2_ NA No comment 2 11/16/ :26-15 ft 2_ NA No comment 2 11/16/ :28-18 ft 2_ NA No comment 2 11/16/ :29-21 ft 2_ NA No comment 2 11/16/ :30-24 ft 2_ NA No comment 2 11/16/ :30-27 ft 2_ NA No comment 2 11/16/ :31-30 ft 2_ NA No comment 2 11/16/ :32-33 ft 2_ NA No comment 2 11/16/ :33-36 ft 2_ NA No comment 2 11/16/ :34-39 ft 2_ NA No comment 2 11/16/ :35-42 ft 2_ NA No comment 2 11/16/ :36-45 ft 2_ NA No comment 2 11/16/ :37-48 ft 2_ NA No comment 2 11/16/ :38-51 ft 2_ NA No comment 2 11/16/ :45-54 ft 2_ NA No comment 2 11/16/ :47-57 ft 2_ NA No comment 2 11/16/ :48-60 ft 2_ NA No comment 2 11/16/ :48-63 ft 2_ NA No comment Comments Turbidity meter not functional on day of the sampling A-7

49 Site Date Time Depth Site/Depth ID Table A1-2. Raw Data Measured at In-Lake Sites Specific Temperature ( C) ance Conduct- ph (ms/cm) Dissolved Oxygen (mg/l) Turbidity (NTU) 2 11/16/ :49-66 ft 2_ NA No comment 2 11/16/ :51-69 ft 2_ NA 2 11/16/ :52-72 ft 2_ NA No comment 2 11/16/ :53-75 ft 2_ NA No comment 2 11/16/ :54-78 ft 2_ NA 3 11/16/ :13 Mud residue was found on the probe when pulled back to the surface Surface 3_ NA No comment 3 11/16/ :14-3 ft 3_ NA No comment 3 11/16/2017 NR -6 ft 3_ NA No comment 3 11/16/2017 NR -9 ft 3_ NA No comment 3 11/16/2017 NR -12 ft 3_ NA No comment 3 11/16/2017 NR -15 ft 3_ NA No comment 3 11/16/2017 NR -18 ft 3_ NA No comment 3 11/16/ :18-21 ft 3_ NA No comment 3 11/16/ :19-24 ft 3_ NA No comment 3 11/16/ :20-27 ft 3_ NA No comment 3 11/16/ :21-30 ft 3_ NA No comment 3 11/16/2017 NR -33 ft 3_ NA No comment 3 11/16/2017 NR -36 ft 3_ NA No comment 3 11/16/2017 NR -39 ft 3_ NA No comment 3 11/16/2017 NR -42 ft 3_ NA No comment Comments Spec. Cond fluctuated between , mostly around A-8

50 Site Date Time Depth Site/Depth ID Table A1-2. Raw Data Measured at In-Lake Sites Specific Temperature ( C) ance Conduct- ph (ms/cm) Dissolved Oxygen (mg/l) Turbidity (NTU) Comments 3 11/16/2017 NR -45 ft 3_ NA No comment 3 11/16/2017 NR -48 ft 3_ NA Observed cord was at ~45 angle, potentially due to wind pushing the boat or current pushing the water 3 11/16/2017 NR -51 ft 3_ NA No comment 3 11/16/2017 NR -54 ft 3_ NA No comment 3 11/16/2017 NR -57 ft 3_ NA No comment 3 11/16/2017 NR - 60 ft 3_ NA No comment 3 11/16/ :29-63 ft 3_ NA No comment 7 11/16/2017 2:31 Surface 7_ NA No comment 7 11/16/2017 NR -3 ft 7_ NA No comment 7 11/16/2017 NR -6 ft 7_ NA No comment 7 11/16/2017 NR -9 ft 7_ NA No comment 7 11/16/2017 NR -12 ft 7_ NA No comment 7 11/16/2017 NR -15 ft 7_ NA No comment 7 11/16/2017 2:35-18 ft 7_ NA No comment 7 11/16/2017 NR - 21 ft 7_ NA No comment 7 11/16/2017 NR -24 ft 7_ NA No comment 7 11/16/2017 NR -27 ft 7_ NA No comment 7 11/16/2017 2:38-30 ft 7_ NA No comment 7 11/16/2017 NR -33 ft 7_ NA No comment 7 11/16/2017 NR -36 ft 7_ NA No comment A-9

51 Site Date Time Depth Site/Depth ID Table A1-2. Raw Data Measured at In-Lake Sites Specific Temperature ( C) ance Conduct- ph (ms/cm) Dissolved Oxygen (mg/l) Turbidity (NTU) 7 11/16/2017 NR -39 ft 7_ NA No comment 7 11/16/2017 NR -42 ft 7_ NA No comment 7 11/16/2017 2:43-45 ft 7_ NA No comment 7 11/16/2017 2:45-48 ft 7_ NA No comment 7 11/16/2017 2:46-51 ft 7_ NA No comment Comments A-10

52 Sample ID Sample Date Table A1-3. Results from HRSD Lab: Nutrient and Sediment Weather Event Analyte Result (mg/l) Below Level of Quantitation (Y/N) 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 Kjeldahl nitrogen 0.50 Y 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 Ammonia as N 0.02 N Above temp. LJ_02 9/8/2017 Dry Orthophosphate as P 0.01 Y Above temp. LJ_02 9/8/2017 Dry Total suspended solids 1.00 Y Above temp. LJ_03 9/8/2017 Dry Total Kjeldahl nitrogen 0.50 Y Above temp. LJ_03 9/8/2017 Dry Total phosphorus 0.01 N Above temp. LJ_03 9/8/2017 Dry Nitrate + nitrite as N 0.01 Y Above temp. LJ_03 9/8/2017 Dry Ammonia as N 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 N Above temp. LJ_04 9/8/2017 Dry Total phosphorus 5.43 N Above temp. LJ_04 9/8/2017 Dry Nitrate + nitrite as N 0.19 N Above temp. LJ_04 9/8/2017 Dry Ammonia as N 7.13 N Above temp. LJ_04 9/8/2017 Dry Orthophosphate as P 0.02 N Above temp. LJ_04 9/8/2017 Dry Total suspended solids 4,73 N Above temp. LJ_05 9/8/2017 Dry Total Kjeldahl nitrogen 2.41 N Above temp. LJ_05 9/8/2017 Dry Total phosphorus 0.38 N Above temp. LJ_05 9/8/2017 Dry Nitrate + nitrite as N 0.09 N Above temp. LJ_05 9/8/2017 Dry Ammonia as N 0.06 N Above temp. Flag A-11

53 Sample ID Sample Date Table A1-3. Results from HRSD Lab: Nutrient and Sediment Weather Event Analyte Result (mg/l) Below Level of Quantitation (Y/N) LJ_05 9/8/2017 Dry Orthophosphate as P 0.02 N Above temp. LJ_05 9/8/2017 Dry Total suspended solids 115 N Above temp. LJ_06 9/8/2017 Dry Total Kjeldahl nitrogen 0.63 N Above temp. LJ_06 9/8/2017 Dry Total phosphorus 0.01 N Above temp. LJ_06 9/8/2017 Dry Nitrate + nitrite as N 0.01 Y Above temp. LJ_06 9/8/2017 Dry Ammonia as N 0.02 N Above temp. LJ_06 9/8/2017 Dry Orthophosphate as P 0.06 N Above temp. LJ_06 9/8/2017 Dry Total suspended solids 2.40 N Above temp. LJ_07 9/8/2017 Dry Total Kjeldahl nitrogen 0.52 N Above temp. LJ_07 9/8/2017 Dry Total phosphorus 0.01 N Above temp. LJ_07 9/8/2017 Dry Nitrate + nitrite as N 0.01 Y Above temp. LJ_07 9/8/2017 Dry Ammonia as N 0.01 N Above temp. LJ_07 9/8/2017 Dry Orthophosphate as P 0.02 N N/A LJ_07 9/8/2017 Dry Total suspended solids 1.40 N Above temp. 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_09 9/8/2017 Dry Total Kjeldahl nitrogen 0.52 N Above temp. LJ_09 9/8/2017 Dry Total phosphorus 0.09 N Above temp. LJ_09 9/8/2017 Dry Nitrate + nitrite as N 0.01 Y Above temp. LJ_09 9/8/2017 Dry Ammonia as N 0.02 N Above temp. LJ_09 9/8/2017 Dry Orthophosphate as P 0.01 Y Above temp. LJ_09 9/8/2017 Dry Total suspended solids 1.60 N Above temp. 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 LJ_04 9/14/2017 Wet Total phosphorus 0.16 N N/A Flag A-12

54 Sample ID Sample Date Table A1-3. Results from HRSD Lab: Nutrient and Sediment Weather Event Analyte Result (mg/l) Below Level of Quantitation (Y/N) LJ_04 9/14/2017 Wet Nitrate + nitrite as N 0.36 N N/A LJ_04 9/14/2017 Wet Ammonia as N 7.17 N N/A LJ_04 9/14/2017 Wet Orthophosphate as P 0.03 N N/A LJ_04 9/14/2017 Wet Total suspended solids N N/A LJ_05 9/14/2017 Wet Total Kjeldahl nitrogen 1.95 N N/A LJ_05 9/14/2017 Wet Total phosphorus 0.18 N N/A LJ_05 9/14/2017 Wet Nitrate + nitrite as N 0.01 Y N/A LJ_05 9/14/2017 Wet Ammonia as N 0.09 N N/A LJ_05 9/14/2017 Wet Orthophosphate as P 0.01 Y N/A LJ_05 9/14/2017 Wet Total suspended solids 74 N N/A LJ_06 9/14/2017 Wet Total Kjeldahl nitrogen 0.50 Y N/A LJ_06 9/14/2017 Wet Total phosphorus 0.01 N N/A LJ_06 9/14/2017 Wet Nitrate + nitrite as N 0.01 Y N/A LJ_06 9/14/2017 Wet Ammonia as N 0.04 N N/A LJ_06 9/14/2017 Wet Orthophosphate as P 0.01 Y N/A LJ_06 9/14/2017 Wet Total suspended solids 3.80 N N/A LJ_08 9/14/2017 Wet Total Kjeldahl nitrogen 8.34 N N/A LJ_08 9/14/2017 Wet Total phosphorus 0.17 N N/A LJ_08 9/14/2017 Wet Nitrate + nitrite as N 0.34 N N/A LJ_08 9/14/2017 Wet Ammonia as N 7.36 N N/A LJ_08 9/14/2017 Wet Orthophosphate as P 0.03 N N/A LJ_08 9/14/2017 Wet Total suspended solids 72 N N/A LJ_09 9/14/2017 Wet Total Kjeldahl nitrogen 0.51 N N/A LJ_09 9/14/2017 Wet Total phosphorus 0.01 N N/A LJ_09 9/14/2017 Wet Nitrate + nitrite as N 0.01 Y N/A LJ_09 9/14/2017 Wet Ammonia as N 0.02 N N/A LJ_09 9/14/2017 Wet Orthophosphate as P 0.01 Y N/A LJ_09 9/14/2017 Wet Total suspended solids 2.40 N N/A LJ_01 10/24/2017 Wet Total Kjeldahl nitrogen 0.55 N N/A LJ_01 10/24/2017 Wet Total phosphorus 0.01 Y N/A LJ_01 10/24/2017 Wet Nitrate + nitrite as N 0.01 Y N/A LJ_01 10/24/2017 Wet Ammonia as N 0.01 N N/A LJ_01 10/24/2017 Wet Orthophosphate as P 0.02 Y Possible matrix interference Flag A-13

55 Sample ID Sample Date Table A1-3. Results from HRSD Lab: Nutrient and Sediment Weather Event Analyte Result (mg/l) Below Level of Quantitation (Y/N) LJ_01 10/24/2017 Wet Total suspended solids 1.50 N N/A LJ_04 10/24/2017 Wet Total Kjeldahl nitrogen 7.31 N N/A LJ_04 10/24/2017 Wet Total phosphorus 0.20 N N/A LJ_04 10/24/2017 Wet Nitrate + nitrite as N 0.24 N N/A LJ_04 10/24/2017 Wet Ammonia as N 5.08 N N/A LJ_04 10/24/2017 Wet Orthophosphate as P 0.01 Y N/A LJ_04 10/24/2017 Wet Total suspended solids 457 N N/A 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 Kjeldahl nitrogen 0.50 Y N/A LJ_06 10/24/2017 Wet Total phosphorus 0.01 Y N/A LJ_06 10/24/2017 Wet Nitrate + nitrite as N 0.01 Y N/A LJ_06 10/24/2017 Wet Ammonia as N 0.02 N N/A LJ_06 10/24/2017 Wet Orthophosphate as P 0.01 N N/A LJ_06 10/24/2017 Wet Total suspended solids 2.00 N N/A LJ_09 10/24/2017 Wet Total Kjeldahl nitrogen 0.55 N N/A LJ_09 10/24/2017 Wet Total phosphorus 0.01 N N/A LJ_09 10/24/2017 Wet Nitrate + nitrite as N 0.01 Y N/A LJ_09 10/24/2017 Wet Ammonia as N 0.02 N N/A LJ_09 10/24/2017 Wet Orthophosphate as P 0.01 Y N/A LJ_09 10/24/2017 Wet Total suspended solids 2.10 N 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 LJ_02 11/16/2017 Dry Total Kjeldahl nitrogen 0.63 N N/A LJ_02 11/16/2017 Dry Total phosphorus 0.01 N N/A Flag A-14

56 Sample ID Sample Date Table A1-3. Results from HRSD Lab: Nutrient and Sediment Weather Event Analyte Result (mg/l) Below Level of Quantitation (Y/N) LJ_02 11/16/2017 Dry Nitrate + nitrite as N 0.01 N N/A LJ_02 11/16/2017 Dry Ammonia as N 0.15 N N/A LJ_02 11/16/2017 Dry Orthophosphate as P 0.01 Y N/A LJ_02 11/16/2017 Dry Total suspended solids 1.80 N N/A LJ_03 11/16/2017 Dry Total Kjeldahl nitrogen 0.56 N N/A LJ_03 11/16/2017 Dry Total phosphorus 0.02 N N/A LJ_03 11/16/2017 Dry Nitrate + nitrite as N 0.02 N N/A LJ_03 11/16/2017 Dry Ammonia as N 0.15 N N/A LJ_03 11/16/2017 Dry Orthophosphate as P 0.01 Y N/A LJ_03 11/16/2017 Dry Total suspended solids 1.50 N N/A LJ_04 11/16/2017 Dry Total Kjeldahl nitrogen 7.77 N N/A LJ_04 11/16/2017 Dry Total phosphorus 0.07 N N/A LJ_04 11/16/2017 Dry Nitrate + nitrite as N 0.82 N N/A LJ_04 11/16/2017 Dry Ammonia as N 6.84 N N/A LJ_04 11/16/2017 Dry Orthophosphate as P 0.01 Y N/A LJ_04 11/16/2017 Dry Total suspended solids 39.6 N N/A LJ_05 11/16/2017 Dry Total Kjeldahl nitrogen 1.69 N N/A LJ_05 11/16/2017 Dry Total phosphorus 0.08 N N/A LJ_05 11/16/2017 Dry Nitrate + nitrite as N 0.13 N N/A LJ_05 11/16/2017 Dry Ammonia as N 0.05 N N/A LJ_05 11/16/2017 Dry Orthophosphate as P 0.01 N N/A LJ_05 11/16/2017 Dry Total suspended solids 9.50 N N/A LJ_06 11/16/2017 Dry Total Kjeldahl nitrogen 0.54 N N/A LJ_06 11/16/2017 Dry Total phosphorus 0.02 N N/A LJ_06 11/16/2017 Dry Nitrate + nitrite as N 0.01 N N/A LJ_06 11/16/2017 Dry Ammonia as N 0.14 N N/A LJ_06 11/16/2017 Dry Orthophosphate as P 0.01 Y N/A LJ_06 11/16/2017 Dry Total suspended solids 3.40 N N/A LJ_07 11/16/2017 Dry Total Kjeldahl nitrogen 0.50 Y N/A LJ_07 11/16/2017 Dry Total phosphorus 0.02 N N/A LJ_07 11/16/2017 Dry Nitrate + nitrite as N 0.03 N N/A LJ_07 11/16/2017 Dry Ammonia as N 0.13 N N/A LJ_07 11/16/2017 Dry Orthophosphate as P 0.01 Y N/A LJ_07 11/16/2017 Dry Total suspended solids 1.30 N N/A Flag A-15

57 Sample ID Sample Date Table A1-3. Results from HRSD Lab: Nutrient and Sediment Weather Event Analyte Result (mg/l) Below Level of Quantitation (Y/N) 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 Kjeldahl nitrogen 0.57 N N/A LJ_09 11/16/2017 Dry Total phosphorus 0.01 Y N/A LJ_09 11/16/2017 Dry Nitrate + nitrite as N 0.05 N N/A LJ_09 11/16/2017 Dry Ammonia as N 0.14 N N/A LJ_09 11/16/2017 Dry Orthophosphate as P 0.01 Y N/A LJ_09 11/16/2017 Dry Total suspended solids 5.20 N 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 Flag A-16

58 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 Algal biomass 1.5 mg/l LJ_03 9/8/2017 Chlorophyll-a 22.4 µg/l LJ_03 9/8/2017 Chlorophyll-b 2.5 µg/l LJ_03 9/8/2017 Chlorophyll-c 0 µg/l LJ_03 9/8/2017 Corrected chlorophyll-a 7.3 µg/l LJ_03 9/8/2017 Pheophytin 25 µg/l LJ_07 9/8/2017 Microcystins/nodularins ND µg/l LJ_07 9/8/2017 Cylindrospermopsin ND µg/l LJ_07 9/8/2017 Anatoxin-a ND µg/l LJ_07 9/8/2017 Algal biomass 0.3 mg/l LJ_07 9/8/2017 Chlorophyll-a 4.4 µg/l LJ_07 9/8/2017 Chlorophyll-b 0.7 µg/l LJ_07 9/8/2017 Chlorophyll-c 1.4 µg/l LJ_07 9/8/2017 Corrected chlorophyll-a 2.5 µg/l LJ_07 9/8/2017 Pheophytin 38 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 LJ_02 11/16/2017 Algal biomass 0.4 mg/l LJ_02 11/16/2017 Chlorophyll-a 6.1 µg/l LJ_02 11/16/2017 Chlorophyll-b 1.8 µg/l LJ_02 11/16/2017 Chlorophyll-c 2.9 µg/l A-17

59 Table A1-4. Results from GreenWater Lab: Algal Properties and Cyanotoxins Sample ID Sample Date Analyte Result Unit LJ_02 11/16/2017 Corrected chlorophyll-a 4.2 µg/l LJ_02 11/16/2017 Pheophytin 3.1 µg/l LJ_03 11/16/2017 Microcystins/nodularins ND µg/l LJ_03 11/16/2017 Cylindrospermopsin 0.33 µg/l LJ_03 11/16/2017 Anatoxin-a ND µg/l LJ_03 11/16/2017 Algal biomass 0.3 mg/l LJ_03 11/16/2017 Chlorophyll-a 4.9 µg/l LJ_03 11/16/2017 Chlorophyll-b 0 µg/l LJ_03 11/16/2017 Chlorophyll-c 0 µg/l LJ_03 11/16/2017 Corrected chlorophyll-a 5.4 µg/l LJ_03 11/16/2017 Pheophytin 0 µg/l LJ_07 11/16/2017 Microcystins/nodularins ND µg/l LJ_07 11/16/2017 Cylindrospermopsin ND µg/l LJ_07 11/16/2017 Anatoxin-a ND µg/l LJ_07 11/16/2017 Algal biomass 0.3 mg/l LJ_07 11/16/2017 Chlorophyll-a 4 µg/l LJ_07 11/16/2017 Chlorophyll-b 1 µg/l LJ_07 11/16/2017 Chlorophyll-c 2.6 µg/l LJ_07 11/16/2017 Corrected chlorophyll-a 2.9 µg/l LJ_07 11/16/2017 Pheophytin 2.9 µg/l A-18

60 Sample ID Site Sampling Date Genus Table A1-5. Results from GreenWater Lab: Cyanobacteria Composition Species Number Counted Counting Unit Cells/ Unit Species (units/ml) Species (cells/ml) Total Cyano (units/ml) LJ_ /8/ LJ_ /8/2017 Merismopedia tenuissima 78 Colony LJ_ /8/2017 Cyanophyte unicell, oval/rod spp. 121 Cell LJ_ /8/2017 Planktolyngbya f. limnetica 5 Filament LJ_ /8/2017 Aphanocapsa delicatissima 9 Colony LJ_ /8/2017 Aphanocapsa sp. 5 Colony LJ_ /8/2017 Cyanophyte cell spp. 33 Colony pair 8 LJ_ /8/2017 Oscillatorialean filament sp. 2 Filament LJ_ /8/2017 Aphanothece sp. 4 Colony LJ_ /8/2017 Aphanocapsa conferta 2 Colony LJ_ /8/2017 Cyanophyte tetrad spp. 6 Colony LJ_ /8/2017 Cyanophyte unicell, sphere spp. 17 Cell LJ_ /8/2017 LJ_ /8/2017 Aphanocapsa sp. 1 Colony LJ_ /8/2017 Oscillatorialean filament sp. 1 Filament LJ_ /8/2017 Nostocalean filament sp. 1 2 Filament Aphanizomenon flos-aquae/klebahn ii 10 Filament Total Cyano (Cells/mL) A-19

61 Sample ID Site Sampling Date Genus Table A1-5. Results from GreenWater Lab: Cyanobacteria Composition Species Number Counted Counting Unit Cells/ Unit Species (units/ml) Species (cells/ml) LJ_ /8/2017 Nostocalean filament sp. 2 4 Filament LJ_ /8/2017 Cylindrospermopsis raciborskii 3 Filament LJ_ /8/2017 Chroococcus minutus 2 Colony Total Cyano (units/ml) LJ_ /8/ LJ_ /8/2017 Merismopedia tenuissima 90 Colony LJ_ /8/2017 Cyanophyte unicell, oval/rod Cyanophyte cell pair spp. 131 Cell LJ_ /8/2017 spp. 29 Colony LJ_ /8/2017 Aphanocapsa conferta 4 Colony LJ_ /8/2017 Aphanocapsa delicatissima 4 Colony LJ_ /8/2017 Aphanothece sp. 3 Colony LJ_ /8/2017 Aphanocapsa sp. 2 Colony LJ_ /8/2017 Cyanophyte tetrad spp. 7 Colony LJ_ /8/2017 Planktolyngbya f. limnetica 1 Filament LJ_ /8/2017 LJ_ /8/2017 LJ_ /8/2017 Cyanophyte unicell, sphere Oscillatorialean filament Nostocalean filament spp. 18 Cell sp. 1 Filament sp. 1 1 Filament Total Cyano (Cells/mL) A-20

62 Sample ID Site Sampling Date Genus Table A1-5. Results from GreenWater Lab: Cyanobacteria Composition Species Number Counted Counting Unit Cells/ Unit Species (units/ml) LJ_ /8/2017 Chroococcus minutus 1 Colony LJ_ /8/2017 LJ_ /8/2017 LJ_ /8/2017 Cylindrospermopsis Nostocalean filament Aphanizomenon flos-aquae/klebahn ii Species (cells/ml) Filament raciborskii 3 Filament sp. 2 3 Filament Total Cyano (units/ml) LJ_ /8/ LJ_ /8/2017 spp. 25 Colony Cyanophyte tetrad LJ_ /8/2017 Planktolyngbya f. limnetica 5 Filament LJ_ /8/2017 Pseudanabaena sp. 4 Filament LJ_ /8/2017 Aphanocapsa conferta 5 Colony LJ_ /8/2017 Cyanophyte cell spp. 23 Colony pair 5 LJ_ /8/2017 Cyanophyte spp. 20 Cell unicell, sphere 3 LJ_ /8/2017 cyanophyte unicell, oval/rod spp. 15 Cell LJ_ /8/2017 Aphanocapsa sp. 1 Colony LJ_ /8/2017 Aphanothece sp. 1 Colony LJ_ /8/2017 Aphanocapsa delicatissima 1 Colony LJ_ /8/2017 Cyanophyte colony sp. 1 Colony Total Cyano (Cells/mL) A-21

63 Sample ID Site Sampling Date LJ_ /8/2017 LJ_ /8/2017 LJ_ /8/2017 LJ_ /8/2017 LJ_2-2 2 LJ_2-2 2 LJ_2-2 2 LJ_2-2 2 LJ_2-2 2 LJ_2-2 2 LJ_2-2 2 LJ_2-2 2 LJ_2-2 2 LJ_2-2 2 LJ_ /16/ /16/ /16/ /16/ /16/ /16/ /16/ /16/ /16/ /16/ /16/20 17 Genus Nostocalean filament Nostocalean filament Nostocalean filament Cylindrospermopsis Pseudanabaena Pseudanabaena Nostocalean filament Cyanophyte cell pair Table A1-5. Results from GreenWater Lab: Cyanobacteria Composition Species Number Counted Counting Unit Cells/ Unit Species (units/ml) sp. 3 2 Filament sp. 1 5 Filament sp. 2 2 Filament raciborskii 1 Filament Aphanizomenon flos-aquae/klebahn ii Species (cells/ml) Filament sp. 3 Filament sp. 3 Filament sp. 7 Filament spp. 19 Colony Planktothrix sp. 1 Filament spp. 21 Cell Filament Merismopedia tenuissima 1 Colony Cyanophyte unicell, oval/rod Sphaerospermopsis aphanizomenoides Dolichospermum sp. 1 Filament Total Cyano (units/ml) Total Cyano (Cells/mL) A-22

64 Table A1-5. Results from GreenWater Lab: Cyanobacteria Composition Sample ID Site LJ_2-2 2 LJ_2-2 2 LJ_2-2 2 LJ_3-2 3 LJ_3-2 3 LJ_3-2 3 LJ_3-2 3 LJ_3-2 3 LJ_3-2 3 LJ_3-2 3 LJ_3-2 3 LJ_3-2 3 LJ_3-2 3 LJ_3-2 3 LJ_3-2 3 Sampling Date 11/16/ /16/ /16/ /16/ /16/ /16/ /16/ /16/ /16/ /16/ /16/ /16/ /16/ /16/ /16/20 17 Genus Species Number Counted Counting Unit Cells/ Unit Species (units/ml) Species (cells/ml) Aphanocapsa sp. 1 Colony Cyanophyte unicell, sphere Dolichospermum spp. 2 Cell cf. planctonicum Aphanizomenon flos-aquae/klebahn ii 10 Filament Filament spp. 20 Colony sp. 8 Filament sp. 1 Filament spp. 21 Cell sp. 1 Filament Filament Planktothrix sp. 10 Filament Cyanophyte cell pair Nostocalean filament Pseudanabaena Cyanophyte unicell, oval/rod Pseudanabaena Sphaerospermopsis aphanizomenoides Dolichospermum sp. 2 Filament Aphanocapsa incerta 1 Colony Cyanophyte unicell, sphere spp. 1 Cell Total Cyano (units/ml) Total Cyano (Cells/mL) A-23

65 Table A1-5. Results from GreenWater Lab: Cyanobacteria Composition Sample ID Site LJ_3-2 3 LJ_3-2 3 LJ_3-2 3 LJ_7-2 7 LJ_7-2 7 LJ_7-2 7 LJ_7-2 7 LJ_7-2 7 LJ_7-2 7 Sampling Date 11/16/ /16/ /16/ /16/ /16/ /16/ /16/ /16/ /16/20 17 Genus Dolichospermum Species cf. planctonicum Number Counted Counting Unit Cells/ Unit Species (units/ml) Species (cells/ml) 2 Filament Merismopedia sp. 1 Colony sp. 1 Filament Aphanocapsa incerta 2 Colony Aphanocapsa conferta 1 Colony Planktolyngbya f. limnetica 2 Filament Cyanophyte unicell, oval/rod Cuspidothrix spp. 2 Cell cf. Dolichospermum issatschenkoi 6 Filament Total Cyano (units/ml) Total Cyano (Cells/mL) A-24

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

67 301 Bendix Road Virginia Beach, VA Technical Memorandum T: F: Prepared for: City of Virginia Beach Project Title: Work Order 18, Task 3 - Lake James Near Term Sampling Project No.: Technical Memorandum 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

68 May 2017 Lake James Water Quality Sampling 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 This technical memo provides the results of the first sampling event, conducted on May 17, 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 interpretation of the sampling results. More complete interpretations of these data will be provided at the completion 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 multiparameter instrument that was calibrated 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 appropriate 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. 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 docx

69 May 2017 Lake James Water Quality Sampling 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 canal 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 upstream portion of the Cedar Hill Canal. Site 6 Located in the Cedar Hill Canal near the discharge pipe from the HRRC groundwater pumping 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. 2 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 docx

70 May 2017 Lake James Water Quality Sampling Figure 1 - Sampling Locations Section 3: Sample Results Sample results for basic water quality parameters, nutrient concentrations, algal toxin analysis, and cyanobacteria enumeration are included in this section. Table 3-1 summarized the results of the field and laboratory analyses. 3 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 docx

71 May 2017 Lake James Water Quality Sampling Parameters Table 3-1. Results of May 2017 Sampling Event Site ph (s.u.) Dissolved Oxygen (mg/l) Temperature (deg C) Specific Conductance (µs/cm) Turbidity (NTU) Ammonia nitrogen (mg/l as N) Nitrate-plus-nitrate nitrogen (mg/l) 0.14 < < Total Kjeldahl Nitrogen (mg/l) Total Phosphorus (mg/l) Orthophosphorus (mg/l as P) < Total Suspended Solids (mg/l) Anatoxin-a (µg/l) -- ND 1 ND Cylindrospermopsin (µg/l) Microcystin-LR (µg/l) Cyanobacteria species Aphanizomenon flos-aquae/klebahnii (cells/ml) Cyanobacteria species Planktothrix agardhii (cells/ml) Cyanobacteria species Aphanothece sp. (cells/ml) Cyanobacteria species Aphanocapsa sp. (cells/ml) Cyanobacteria species oscillatorialean filament sp. (cells/ml) Cyanobacteria species Geitlerinema/Jaaginema sp. (cells/ml) Cyanobacteria species Pseudanabaena sp. (cells/ml) Cyanobacteria species cyanophyte cell pair spp. (cells/ml) Cyanobacteria species cyanophyte unicell, oval/rod spp. (cells/ml) ,446 73, ,904 2, , , Not detected above the method detection limit. The Method Detection Limit for Microcystin is 0.15, Cylndrespermopsin is 0.09, and Anatoxin-a is 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 docx

72 May 2017 Lake James Water Quality Sampling 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 wetweather conditions. Future monitoring will incorporate additional components and analysis including monitoring of lake water quality profiles in mid-lake locations, analysis of chlorophyll-a, sampling of Lake Christopher, and a more detailed examination of the effects of the HRRC discharge on the canal water quality. Following 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 downstream 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 phosphorus (as measured by orthophosphorus) was relatively low in the canal: ~0.01 mg/l in most samples. 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 orthophosphorus. Site 2 ratios suggest N-limitation, whereas site 3 ratios suggest P limitation. Some dissolved organic nitrogen might also be bioavailable. The potential for nutrient limitations will be evaluated 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-aquae/klebahnii, a nitrogen-fixing taxon which is capable of producing cyanotoxins. The second-most abundant taxon was Planktothrix agardhii, which is also capable of producing 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 cyanobacteria abundance of 20, ,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. 5 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 docx

73 May 2017 Lake James Water Quality Sampling Attachment A: Sample Locations Site visit was conducted on May 17, A-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 docx

74 May 2017 Lake James Water Quality Sampling Figure A-1 - Site 1 A-2 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 docx

75 May 2017 Lake James Water Quality Sampling Figure A-2 - Site 2 A-3 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 docx

76 May 2017 Lake James Water Quality Sampling Figure A-3 - Site 3 A-4 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 docx

77 May 2017 Lake James Water Quality Sampling Figure A-4 - Site 4 A-5 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 docx

78 May 2017 Lake James Water Quality Sampling Figure A-5 - Site 6 A-6 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 docx

79 May 2017 Lake James Water Quality Sampling Figure A-6 - Site 7 A-7 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 docx

80 May 2017 Lake James Water Quality Sampling Figure A-7 - Site 8 A-8 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 docx