Cyanobacteria Mitigation Program Application Event #4

Area of Interest (AOI)-Pamunkey

Application date:  August 11, 2022

Pre-application monitoring dates: August 10-11, 2022

Post-application monitoring dates: August 12-14, 2022

Application Tracks - GPS tracks of application locations on August 11th, 2022

AOI-Pamunkey

image will be uploaded when available


Data Plots

LACA monitors the lake prior to, during, and after each application event.  LACA collects field parameters using a YSI ProDSS handheld instrument.  The primary field parameters monitored by LACA include water temperature, pH, specific conductivity, and dissolved oxygen.  We also collect water samples for analysis using LACA owned instruments.  These instruments provide data on the amount of chlorophyll (CHL) and phycocyanin (PC) in each sample.  Chlorophyll is a chemical pigment used by plants and cyanobacteria to produce energy through the process of photosynthesis.  Phycocyanin is a chemical pigment only found in cyanobacteria.  The instruments we use provide us data on the concentrations of each pigment in the samples we collect.  We use these data, along with the field parameters collected with our ProDSS handheld device, to give us indications of the concentrations of cyanobacteria in the water.  The images below provide the pH and dissolved oxygen (DO) field parameters data over a fie day period for each sampling site in AOI-Goldmine and AOI-Duckinhole.

Note that the images below are thumbnails - click on an image to bring it into the view and then click on it again to get to a full page image.  You can save a plot to your computer if you right-click on the image and select "Save Image As" .  

LACA continues to monitor each of the Areas of Interest on a weekly basis after the application event has been completed for cyanobacteria population growth and all of the data will be considered in our project report to be developed after the 2022 recreational season. 


Application Event #4 Observations and Insights

LACA project managers collected several observations and insights from the fourth application event.  These observations and insights, along with the observations and insights from the previous application events will be reviewed and analyzed over the next few months and LACA will release a final report for public review.  The final report is planned to be released no later than December 31st, 2022. 

Please direct questions or comments on these observations and insights to kicktheHAB@lakeannavirginia.org.

AE4 Product Application Plan

The original plan for AE4 was to treat AOI-Duckinhole and AOI-Goldmine on August 11th and 12th.  AE4 was originally planned to be followed by AE5 on August 15th and 16th with treatments in AOI-Pamunkey and AOI-Beverly.

LACA conducted monitoring and analysis of all 12 experiment stations on the 2nd of August in conjunction with the Department of Environmental Quality (DEQ) monthly sampling of the upper lake.  DEQ collected 6 water samples for LACA analysis.  The combined LACA and DEQ sampling and analysis on August 2nd covered 18 stations providing wide coverage of the upper lake north of the Splits. Data generated from the samples collected on August 2nd indicated that cyanobacteria densities in AOI-Pamunkey remained stable and that the area treated with the Lake Guard Oxy product was responding as expected to the preventative dosing in June (8 lbs./acre) and maintenance dosing in July (4 lbs./acre).  August 2nd data for AOI-Duckinhole, AOI-Goldmine, and AOI-Beverly showed elevated cyanobacteria densities.  The elevated levels of cyanobacteria populations significantly lowered the probability of success from a maintenance dose of Lake Guard Oxy product in these three AOIs. 

The data for the 18 stations sampled on August 2nd were reviewed by the LACA project manager and scientists from BlueGreen Water Technologies and a decision was made to adjust the plan for AE4 and to cancel AE5.  The adjustment to AE4 was to treat AOI-Pamunkey with a second maintenance dose of 4 lbs. of Lake Guard Oxy per acre (first maintenance dose conducted in July after a preventative dosing in June).  Treatments of AOI-Goldmine, AOI-Duckinhole, and AOI-Beverly were cancelled due to the data indicating higher than normal cyanobacteria densities in each of those AOIs.

AOI Details:

AOI-Pamunkey covers an area of approximately 200 acres. We treated AOI-Pamunkey with 4 pounds of Lake Guard Oxy per acre on August 11th.  Based on lake and wind conditions, the product was dispersed in a manner like the dosing conducted in July.  The ground track of the application is shown on the image included in this web report.

Day 0 (August 10) Recap:  The LACA Project Managers decided to sample all upper lake stations (all four AOIs – 12 sampling stations) on the day prior to the planned application based on the changes made to the AE4 and AE5 plan.  Cyanobacteria density data were reviewed after sampling and levels in AOI-Pamunkey remained stable and consistent with previous readings from June, July, and early August.  Cyanobacteria density data from AOI-Goldmine and AOI-Duckinhole had recovered to levels close to where they had been in mid-July.  Cyanobacteria density data from AOI-Beverly had recovered to levels below where they had been in mid-July. 

LACA Project Managers decided to stay with the revised treatment plan to gather additional data on AOI-Goldmine, AOI-Duckinhole, and AOI-Beverly through mid-August to inform decisions on additional treatments in the AOIs either in late August or early September.  The primary consideration for additional treatments is if the AOI cyanobacteria density in the AOI are below levels that can be adequately treated with a non-bloom concentration dosing of the Lake Guard Oxy product.

Day 1 (August 11) Recap:  Day 1 sampling of four stations on Pamunkey Creek consisted of 2 stations inside AOI-Pamunkey and 2 stations outside the AOI.  Sampling at all four stations took place prior to dispersal operations of the Lake Guard Oxy product.  SOLitude Lake Management, a certified, licensed applicator, conducted the dispersal operations of 4 pounds of Lake Guard Oxy covering the 80 acres of AOI-Pamunkey west of the Pamunkey Bridge (route 522).  Dispersal operations took place under partly sunny to overcast skies under calm conditions during the first part of the morning turning to a slight breeze around 9:30 am.  Some surface scum was noticed deep in AOI-Pamunkey west of the Pamunkey Bridge (route 522).

Day 2 (August 12) Recap:  Day 2 sampling of the four Pamunkey Creek stations took place under initially overcast skies that turned to sunny/clear around 8:30 am.  Winds were initially calm transitioning to slight and then moderate winds through the sampling session. No surface scum was identified in AOI-Pamunkey or in the stations downstream of AOI-Pamunkey.

Day 3 (August 13) Recap:  Day 3 sampling of the four Pamunkey Creek stations took place under sunny skies with calm to slightly breezy winds.  No surface scum was identified in AOI-Pamunkey or at the stations downstream of AOI-Pamunkey.

Day 4 (August 14) Recap:  Day 4 sampling of the four Pamunkey Creek stations took place under calm conditions with partly cloudy skies.  Thick areas of bubbles and what appeared to be surface scum were seen at station B24 just east of the Pamunkey Bridge.  There were scattered areas of red scum across most areas west of Pamunkey bridge (stations L38 and PMCE1). 

The red scum is suspected to be from a species of Euglena, a non-cyanobacteria organism belonging to the Protozoa kingdom.  Euglena has been found in Lake Anna in past years, most recently in upper parts of Pamunkey Creek and in Terrys’ Run.  Since Euglena is not a cyanobacteria, cell densities are not included in the Virginia Department of Health (VDH) cell count data.  Research papers indicate that several species of Euglena can produce a toxin named euglenophycin.  This toxin is thought to be a neurotoxin similar in function to the venom of fire ants.  Due to the potential toxin production of certain Euglena species, LACA is conducting research on Euglena and will discuss analysis options with Virginia Tech and commercial labs that can classify the exact species.

Data Tabulation:

Field and laboratory parameters for surface water (0.3m depth) for the two stations in AOI-Pamunkey are provided in the tables below.

Field and laboratory parameters for the stations in AOI-Goldmine, AOI-Duckinhole, and AOI-Beverly are available in the cumulative data file (link available here).  Data plots are included in the Data Plots section of this web page.

Cells shaded in gray are pre-application values for each station (data from June 16th for AOI-Pamunkey)


Parameter: Secchi Depth (m)

AOI

Pamunkey

Pamunkey

Date

L38

PMCE1

Pre-Application Values

0.35

0.35

Day 0
(10 August)

0.30

0.40

Day 1
(11 August)

0.35

0.30

Day 2
(12 August)

0.30

0.35

Day 3
(13 August)

0.45

0.45

Day 4
(14 August)

0.30

0.30


Parameter: pH (SU)

AOI

Pamunkey

Pamunkey

Date

L38

PMCE1

Pre-Application Values

9.26

8.99

Day 0
(10 August)

8.12

8.78

Day 1
(11 August)

7.16

7.38

Day 2
(12 August)

7.60

7.79

Day 3
(13 August)

8.41

8.53

Day 4
(14 August)

8.78

8.55


Parameter: DO (mg/L)

AOI

Pamunkey

Pamunkey

Date

L38

PMCE1

Pre-Application Values

10.92

10.67

Day 0
(10 August)

8.51

10.61

Day 1
(11 August)

5.89

6.39

Day 2
(12 August)

7.30

7.78

Day 3
(13 August)

8.88

8.91

Day 4
(14 August)

9.83

9.71


Parameter: DO (%)

AOI

Pamunkey

Pamunkey

Date

L38

PMCE1

Pre-Application Values

141.3

136.4

Day 0
(10 August)

112.3

140.8

Day 1
(11 August)

76.7

83.0

Day 2
(12 August)

93.5

98.7

Day 3
(13 August)

109.3

110.4

Day 4
(14 August)

123.3

121.0


Parameter: Phycocyanin [PC] (RFU)

AOI

Pamunkey

Pamunkey

Date

L38

PMCE1

Pre-Application Values

7,370.7

6,994.6

Day 0
(10 August)

6,016.3

4,904.5

Day 1
(11 August)

6,645.3

7,379.7

Day 2
(12 August)

6,641.9

6,313.2

Day 3
(13 August)

6,260.2

5,958.6

Day 4
(14 August)

5,265.0

5,557.0


PC Increase/Decrease from Pre-Application Value (%)

AOI

Pamunkey

Pamunkey

Date

L38

PMCE1

Day 0
(10 August)

-18.4%

-29.9%

Day 1
(11 August)

-9.8%

5.5%

Day 2
(12 August)

-9.9%

-9.7%

Day 3
(13 August)

-15.1%

-14.8%

Day 4
(14 August)

-28.6%

-20.6%


Parameter: Chlorophyl [CHL] (RFU)

AOI

Pamunkey

Pamunkey

Date

L38

PMCE1

Pre-Application Values

16,601.7

16,578.7

Day 0
(10 August)

15,540.3

15,517.3

Day 1
(11 August)

16,267.0

10,919.7

Day 2
(12 August)

17,323.7

16,060.7

Day 3
(13 August)

14,904.3

14,826.0

Day 4
(14 August)

11,599.7

14,410.0


CHL Increase/Decrease from Pre-Application Value (%)

AOI

Pamunkey

Pamunkey

Date

L38

PMCE1

Day 0
(10 August)

-6.4%

-6.4%

Day 1
(11 August)

-2.0%

-34.1%

Day 2
(12 August)

4.3%

-3.1%

Day 3
(13 August)

-10.2%

-10.6%

Day 4
(14 August)

-30.1%

-13.1%


Parameter: Ratio of PC:CHL

AOI

Pamunkey

Pamunkey

Date

L38

PMCE1

Pre-Application Values

0.444

0.422

Day 0
(10 August)

0.387

0.316

Day 1
(11 August)

0.409

0.676

Day 2
(12 August)

0.383

0.393

Day 3
(13 August)

0.420

0.402

Day 4
(14 August)

0.454

0.386


Observations & Insights:

Field Data (pH and dissolved oxygen):  pH and dissolved oxygen levels in AOI-Pamunkey continued to remain below June’s pre-applications levels.

Lab Data (phycocyanin and chlorophyll):  Phycocyanin levels remained low through Day 4 of AE4 with readings being 28.6% lower than June pre-application levels at station L38 and 20.6% lower at station PMCE1.  Chlorophyll levels also remained low through Day 4 with a readings 30.1% lower than June pre-application levels at station L38 and 13.1% lower at station PMCE1.

AOI-Pamunkey continues to respond, in terms of both field and lab parameters, in a positive manner to the June, July and August Lake Guard Oxy treatments.  This response provides LACA with valuable information on timing of treatments and dosage levels.

There were no adverse environmental effects from the Lake Guard Oxy noted from August 10th through 14th.  

Next Steps

- LACA will continue to monitor phycocyanin and chlorophyll levels across the entire upper Lake Anna area. 

- LACA will collect water samples and field parameters on a weekly basis at all AOI stations.

- Lessons learned from the first four application events will be considered by LACA program managers to determine if any further treatments are advisable to address pilot/demonstration program research questions/data needs.

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