Cyanobacteria Mitigation Program Application Event #2

Area of Interest (AOI)-Goldmine and AOI-Duckinhole

Application dates:  July 14-15, 2022

Post-application monitoring dates: July 16-18, 2022

Application Tracks - GPS tracks of application locations on July 14th, 2022

AOI-Duckinhole


Application Tracks - GPS tracks of application locations on July 14th, 2022

AOI-Goldmine


Application Tracks - GPS tracks of application locations on July 15th, 2022

AOI-Duckinhole


Application Tracks - GPS tracks of application locations on July 15th, 2022

AOI-Goldmine


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 #2 Observations and Insights

LACA project managers collected several observations and insights from the second application event.  These observations and insights informed our planning and execution for application event 3 on July 18th and 19th. 

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

AOI Details and Product Application Plan:  AOI-Goldmine covers an area of approximately 46 acres.  AOI-Duckinhole covers an area of approximately 42 acres.  We treated each AOI with 4 pounds of Lake Guard Oxy per acre over a 2-day period (2 pounds per day). The product was dispersed each day using wind direction and speed and other environmental considerations to determine dispersal tracks.  Actual ground tracks of the application are shown on the images included in this web report.

Day 1 (July 14) Recap:  Day 1 dispersal operations took place under sunny skies with calm winds mainly out of the north/northwest.  Water conditions were normal to the naked eye. 

LACA’s lab parameters taken before the application event indicate that moderate, pre-bloom cyanobacteria activities existed in each AOI prior to product application. 

Day 2 (July 15) Recap:  Day 2 dispersal operations took place under partly cloudy skies turning to sunny later in the morning.  Winds were calm early in the morning changing to slight breeze conditions by the end of the application activities.  Winds were again primarily out of the north/northwest.  There had been some rain in the watershed the night before and the water in AOI-Goldmine showed signs of storm debris and mud.  There were no signs of storm debris or mud in AOI-Duckinhole. 

Day 3 (July 16) Recap (sampling only – no application of Lake Guard Oxy product):  Day 3 sampling took place under partly cloudy and overcast skies with a light rain starting about halfway through sampling activities.  Winds were calm initially but picked up as the rain came in from the west.  Signs of the Lake Guard Oxy product were seen on the surface of both AOIs.  The product appeared to be well-dispersed in the treatment areas 

Day 4 (July 17) Recap (sampling only – no application of Lake Guard Oxy product):  Day 4 sampling took place under overcast skies turning to sunny as the morning progressed.  Winds were calm throughout the morning sampling session.  Signs of the Lake Guard Oxy product were seen on the surface in AOI-Goldmine. 

Day 5 (July 18) Recap (sampling only – no application of Lake Guard Oxy product):  Day 5 sampling took place under sunny skies initially but turned to partly cloudy and then overcast as the session went into the late morning hours.  Winds were calm throughout the morning sampling session.  Sampling on this day wase conducted after the application of Lake Guard Oxy in AOI-Pamunkey and AOI-Beverly as part of Application Event #3.  See the webpage for Application Event #3 for details on those AOIs. 

Data Tabulation:

Field parameters for surface water (0.3m depth) for two stations in each AOI are provided in the tables below.  Cells shaded in gray are pre-application values for each station.

Parameter: Secchi Depth (m)

AOI

Goldmine

Goldmine

Duckinhole

Duckinhole

Date

B21

GMCE1

B20

DKCE1

Day 1 (14 July)

0.4

0.4

0.4

0.25

Day 2 (15 July)

0.3

0.3

0.4

0.4

Day 3 (16 July)

0.3

0.35

0.35

0.35

Day 4 (17 July)

0.3

0.3

0.45

0.35

Day 5 (18 July)

0.4

0.4

0.5

0.4


Parameter: pH (SU)

AOI

Goldmine

Goldmine

Duckinhole

Duckinhole

Date

B21

GMCE1

B20

DKCE1

Day 1 (14 July)

8.49

8.11

8.54

7.69

Day 2 (15 July)

7.37

7.46

9.20

9.02

Day 3 (16 July)

8.17

8.48

8.77

8.36

Day 4 (17 July)

8.45

8.18

7.46

8.23

Day 5 (18 July)

7.26

6.78

8.13

7.66


Parameter: DO (mg/L)

AOI

Goldmine

Goldmine

Duckinhole

Duckinhole

Date

B21

GMCE1

B20

DKCE1

Day 1 (14 July)

9.50

8.75

9.29

8.77

Day 2 (15 July)

7.14

7.81

10.31

9.83

Day 3 (16 July)

8.52

9.06

8.94

8.45

Day 4 (17 July)

9.18

8.86

7.24

8.55

Day 5 (18 July)

7.77

5.94

8.30

8.15


Parameter: DO (%)

AOI

Goldmine

Goldmine

Duckinhole

Duckinhole

Date

B21

GMCE1

B20

DKCE1

Day 1 (14 July)

121.7

112.0

119.0

111.4

Day 2 (15 July)

89.3

96.3

133.0

125.2

Day 3 (16 July)

110.9

117.9

116.1

109.4

Day 4 (17 July)

118.2

113.6

93.4

109.8

Day 5 (18 July)

100.0

74.8

108.2

104.9


Parameter: Phycocyanin [PC] (RFU)

AOI

Goldmine

Goldmine

Duckinhole

Duckinhole

Date

B21

GMCE1

B20

DKCE1

Day 1 (14 July)

4,686.4

3,786.4

6,960.9

6,579.4

Day 2 (15 July)

2,608.6

2,251.1

4,631.7

4,514.6

Day 3 (16 July)

4,764.1

4,359.1

5,569.1

5,648.2

Day 4 (17 July)

4,799.7

4,272.7

5,091.5

4,926.7

Day 5 (18 July)

1,916.4

495.6

6,540.1

4,753.9


PC Increase/Decrease from Day 1 Value (%)

AOI

Goldmine

Goldmine

Duckinhole

Duckinhole

Date

B21

GMCE1

B20

DKCE1

Day 2 (15 July)

-44.3%

-40.5%

-33.5%

-31.4%

Day 3 (16 July)

1.7%

15.1%

-20.0%

-14.2%

Day 4 (17 July)

2.4%

12.8%

-26.9%

-25.1%

Day 5 (18 July)

-59.1%

-86.9%

-6.0%

-27.7%


Parameter: Chlorophyl [CHL] (RFU)

AOI

Goldmine

Goldmine

Duckinhole

Duckinhole

Date

B21

GMCE1

B20

DKCE1

Day 1 (14 July)

11,662.3

7,619.6

14,279.7

13,661.0

Day 2 (15 July)

6,434.7

4,756.2

10,768.1

9,669.4

Day 3 (16 July)

10,536.8

6,873.6

9,785.1

10,938.4

Day 4 (17 July)

10,212.0

8,561.2

11,450.3

11,159.5

Day 5 (18 July)

4,969.6

3,884.8

10,432.7

10,200.9


CHL Increase/Decrease from Day 1 Value (%)

AOI

Goldmine

Goldmine

Duckinhole

Duckinhole

Date

B21

GMCE1

B20

DKCE1

Day 2 (15 July)

-44.8%

-37.6%

-24.6%

-29.2%

Day 3 (16 July)

-9.7%

-9.8%

-31.5%

-19.9%

Day 4 (17 July)

-12.4%

12.4%

-19.8%

-18.3%

Day 5 (18 July)

-57.4%

-49.0%

-26.9%

-25.3%


Parameter: Ratio of PC:CHL

AOI

Goldmine

Goldmine

Duckinhole

Duckinhole

Date

B21

GMCE1

B20

DKCE1

Day 1 (14 July)

0.402

0.497

0.487

0.482

Day 2 (15 July)

0.405

0.473

0.430

0.467

Day 3 (16 July)

0.452

0.634

0.569

0.516

Day 4 (17 July)

0.470

0.499

0.445

0.441

Day 5 (18 July)

0.386

0.128

0.627

0.466


Observations & Insights:

On Day 2, pH and dissolved oxygen levels decreased in AOI-Goldmine but all three field parameters increased in AOI-Duckinhole.  This increase in AOI-Duckinhole was unexpected and will be researched further.

The measured lab parameters on Day 2 showed decreases of phycocyanin and chlorophyll levels from Day 1 – pre-application values in both AOIs (the desired effect).  The decrease in phycocyanin and chlorophyl levels in AOI-Duckinhole while field parameters increased is an area for further research and data analysis.

Phycocyanin levels were down significantly after Day 1 in both AOIs (40-44% at stations in AOI-Goldmine and 31-33% at stations in AOI-Duckinhole)

Phycocyanin levels remained low through Day 5 in both AOIs (down 59-87% at stations in AOI-Goldmine and down 6-28% at stations in AOI-Duckinhole).

Chlorophyl levels were down significantly after Day 1 in both AOIs (38-45% at stations in AOI-Goldmine and 25-29% at stations in AOI-Duckinhole)

Chlorophyl levels remained low through Day 5 in both AOIs (down 49-57% at stations in AOI-Goldmine and down 25-27% at stations in AOI-Duckinhole)

Other, non-treated areas of the upper North Anna River were monitored by the Virginia Department of Environmental Quality (DEQ) on July 7th and the North Anna stations were placed under recreational advisory due to high cyanobacteria cell counts (high population densities).  LACA observations on the Upper North Anna during the Application Event #2 timeframe indicated continued cyanobacteria bloom conditions in most of the Upper North Anna River.

There were no adverse environmental effects from the Lake Guard Oxy noted from July 14th through 18th.  LACA observed the entire lengths of Goldmine and Duckinhole Creeks during this timeframe.  

Next Steps

- LACA closely monitors phycocyanin and the ratio of phycocyanin to chlorophyll across the entire upper Lake Anna area.  Data indicate that the treated areas in AOI-Goldmine and AOI-Duckinhole remained below our level of concern thresholds while other areas of the upper lake trended higher due to higher water temperatures, sun angle, and other environmental conditions.  The Virginia Department of Health (VDH) had not declared a recreational advisory for any area of Lake Anna at the completion of Application Event #1 but LACA data indicates that the North Anna River and Terry's Run are trending closely to 2021 data.  These two tributaries went under VDH advisory in July of 2021 so they will be treated during our July mitigation activities.

- Lessons learned from Application Event #2 were applied to Application Event #3 and will be applied for August application events.


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