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Blue Green Algae Update

We received toxin analysis from the State DEC on a sample that was collected on August 19th showing a level of 20ug/L of the toxin microcystin, which just meets the DEC Confirmed with High Toxins Bloom threshold of 20ug/L for a shoreline sample. The size of the bloom was small and localized. This result increases the need to use visual indicators to avoid the bloom areas.

Watershed staff went out today (Friday) with FLCC instructor Patty Thompson to do our monthly lake sampling program. We started at the south end launch and sampled 14 different near shoreline locations and two mid lake areas for a variety of chemical and physical parameters. Clarity in the mid lake area near Bristol Harbour was 8 meters- which is great for this time of year. However, with the calm winds we did see some light streaking of algae in the water column and dots in the water. We collected a sample in the area where the algae was streaking and had it screened at FLI. The results showed elevated concentrations but below bloom levels. This was the highest density location that we saw on the lake today.

We then proceeded north and patrolled both the near shore and mid lake areas. Our North Basin clarity reading is located mid lake near Deep Run Beach/old Thendara. The clarity reading here was 5 meters- which is more typical for this time of year. By comparison- during the 2015 bloom we were getting clarity readings of only 2.5 meters. We saw dots in the water at this location- but no streaking. Many of the near shore areas looked fairly clear in the northern half of the lake- but we would occasionally see areas that had more dots in the water. We also received reports of light streaking that would dissipate after a period of time.

The take home message from all of this information is that overall the vast majority of the lake is still well below bloom concentrations, but (and this is important)- there will be isolated pockets of algae that will concentrate in both the shoreline and mid lake areas- especially if there is calm or slight breeze levels. We typically see the concentrations increase on the windward side of the lake- however this is not always the case. Please use your visual indicators of lots of dots or streaking to make decisions on where to recreate this labor day weekend. As we have learned over the last three years- conditions can change rapidly on the lake. The weather looks like it will be sunny and warm which will potentially increase the ability for Blue Green Algae to increase in density.

Feel free to contact us: Kevin Olvany Canandaigua Lake Watershed Council Program Manager (585) 747-8719 Lindsay McMillan Association Director, CLWA (585) 394-5030

More Information on Blue Green Algae

Click below for our Harmful Algae Bloom brochure.

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