2022 Cynobacteria Testing in Lake Garfield
Every two weeks starting in June, Shannon Poulin has been taking water samples from our lake. See her reports below.
June 20, 2022
On June 20, 2022, one sample was taken on the surface of the Big Bowl and one at 20 feet in the Big Bowl in 29.3 feet of water. The phycocyanin levels were at 0.10 parts per billion which is extremely low for both samples. The cell counts at the surface were 320 cells/mL of Microcystis. The cell counts at 20 feet were 780 cells/mL of Microcystis. Neither location had cell counts that are near the state’s threshold, therefore the lake is safe at this time.
Compared to previous years, Microcystis was the only cyanobacteria found this year whereas Dolichospermum and Aphanizomenon were also found. The total cell counts were also higher than this time last year than this year. The lake is about 5 degrees colder than last year at the same sampling time.
The temperature and dissolved oxygen were taken at 1 to 25 feet. The oxygen levels were steady for the first 20 feet then decreased below 2 mg/L. The secchi disc had a reading of 9.5 feet.
On June 25, 2022, Michael contacted me about an abundance of algae on the surface of the small bowl. I was in the area and collected a few samples. The determination of the algae was brown and green algae.
Figure 1. Estimated Lake Stratification (where 0 is the surface of the lake).
June 6, 2022
On June 6, 2022, two samples were taken one at the surface in the big bowl and the other at 25 feet in the big bowl. The phycocyanin levels were at 0.10 parts per billion for both samples which is extremely low. The cell counts were 400 cells/mL of Microcystis. The cell counts at 25 feet was 200 cells/mL of Microcystis. The cell counts are nowhere near the state’s threshold of 70,000 cells/mL. At this time the lake is okay.
Compared to last year the results are the same as last year and that the cyanobacteria levels are low. Also, to note is that the surface temperature of the lake at sampling time this year was 3 degrees Celsius colder than at the same time last year.
The temperature and dissolved oxygen (mg/l) were collected 1 to 25 feet. The oxygen increased from 15 to 20 feet. Then dropped below 2 mg/l at 25 feet. The secchi depth was 14.1 feet meaning the water was pretty clear.
Figure 1. Estimated Lake Stratification
July 11, 2022
On July 11, 2022, one sample was taken on the surface of the Big Bowl, one in the Small Bowl, and one at 25 feet in the Big Bowl in 29.8 feet of water. The phycocyanin levels were at 0.10 parts per billion which is extremely low for all samples. The cell counts at the surface of the Big Bowl were 1,600 cells/mL of Microcystis and at the surface of the Small Bowl were 800 cells/mL of Microcystis. The cell counts at 25 feet were 750 cells/mL of Microcystis and 1,800 cells/mL of Dolichospermum for a total of 2,550 cells/mL. None of the locations had cell counts that are near the state’s threshold, therefore the lake is safe at this time.
Compared to previous years the cell counts are higher this year than last year and the phycocyanin levels were the same as last year.
The temperature and dissolved oxygen were taken at 1 to 27 feet. The oxygen levels were steady for the first 20 feet then decreased below 2 mg/L. The secchi disc had a reading of 12.8 feet which has increased since the last sampling.
Figure 1. Estimated Lake Stratification (where 0 is the surface of the lake).
July 29, 2022
On July 29, 2022, one sample was taken in the Small Bowl, and one at 20 feet in the Big Bowl in 29.4 feet of water. The phycocyanin levels were at 0.10 parts per billion which is extremely low for all samples. The cell counts at the surface of the Small Bowl were 375 cells/mL of Microcystis. The cell counts at 20 feet were 660 cells/mL of Microcystis. Neither location had cell counts that are near the state’s threshold, therefore the lake is safe at this time.
Compared to previous years the cell counts are the same as last year and the phycocyanin levels were the same as last year.
The temperature and dissolved oxygen were taken at 1 to 27 feet. The oxygen levels were steady for the first 15 feet increased at 20 feet, then decreased. The secchi disc had a reading of 17.7 feet which has increased since the last sampling.
Figure 1. Estimated Lake Stratification (where 0 is the surface of the lake).
August 8, 2022
On August 8, 2022, one sample was taken in the Small Bowl, and one at 25 feet in the Big Bowl in 29.4 feet of water. The phycocyanin levels were at 0.10 parts per billion which is extremely low for all samples. The cell counts at the surface of the Small Bowl were 1,200 cells/mL of Microcystis. The cell counts at 25 feet were 1,000 cells/mL of Microcystis. Neither location had cell counts that are near the state’s threshold, therefore the lake is safe at this time.
Compared to previous years the cell counts are the same as last year and the phycocyanin levels were the same as last year.
The temperature and dissolved oxygen were taken at 1 to 27 feet. The oxygen levels were steady for the first 15 feet increased at 20 feet, then decreased. Secchi disc reading was not taken at this sampling as I could not safely lean over the jet ski to see the disc without tipping over.
Figure 1. Estimated Lake Stratification (where 0 is the surface of the lake).
August 29, 2022
On August 29, 2022, one sample was taken in the Small Bowl, and one at 15 feet in the Big Bowl in 28.7 feet of water. The phycocyanin levels were at 0.10 parts per billion which is extremely low for all samples. The cell counts at the surface of the Small Bowl were 1,000 cells/mL of Microcystis. The cell counts at 15 feet were 1,300 cells/mL of Microcystis and 160 cells/mL for Dolichospermum. Neither location had cell counts that are near the state’s threshold, therefore the lake is safe at this time.
Compared to previous years the cell counts are the same as last year and the phycocyanin levels were the same as last year.
The temperature and dissolved oxygen were taken at 1 to 25 feet. The oxygen levels were steady for the first 10 feet then decreased at 15 feet, and then decreased below 2 mg/L at 20 feet. The secchi disc reading was 7.9 feet which is pretty clear.
Figure 1. Estimated Lake Stratification (where 0 is the surface of the lake).
September 19, 2022
On September 19, 2022, one sample was taken in the Small Bowl. A depth sample was not taken at this time because I had to get off the water because of the weather. The phycocyanin levels were at 0.10 parts per billion which is extremely low for the sample. The cell counts at the surface of the Small Bowl were 750 cells/mL of Microcystis. The surface location had cell counts that are near the state’s threshold, therefore the lake is safe at this time.
Compared to previous years the cell counts are lower than last year as a small bloom was occurring on the lake.
The temperature and dissolved oxygen were taken at 1 to 25 feet. The oxygen levels were steady for the first 10 feet then decreased at 15 feet, and then decreased below 2 mg/L at 20 feet. The secchi disc reading was 8.9 feet which has increased since the last sampling.
Figure 1. Estimated Lake Stratification (where 0 is the surface of the lake).
Taxa abrevation as follows:
Doli=dolichospermum
Micro=Microcystis
Apha=amphazamenon
Limn=Limnoraphis
Woro=woronichinia