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Water Quality Update for September 25, 2020

The first week of fall is upon us. We are starting to see docks coming out for the season, boats getting winterized, and a renewed focus on yard chores.

Here at CLWA, we are still going strong with a dedicated group of volunteers continuing to submit their weekly secchi disk reports and send in shoreline HABs surveys. We thank them for their ongoing efforts to provide us with lake condition reports. Last week (week ending 9/20), 9 volunteers submitted clarity readings with a weekly average of 5.47 meters, which was an increase in water clarity from the previous week’s average of 5 meters (week ending 9/13). Remember that clarity is a measure of algal abundance and suspended sediments in the water column. Volunteers also reported a drop in the average surface water temperature this past week. Clarity is increasing, and surface water temperatures are starting to decrease, which should result in fewer HAB reports as we move through October. 

We have, however, had several blooms reported so far this week, including three bloom reports coming in just this afternoon. Today's calm winds and sunny weather are the perfect conditions for HABs. Therefore, it is still wise to scan the shoreline before entering the water or letting pets swim. 

Volunteers collected 4 samples earlier this week from very obvious bloom areas and results from the Finger Lakes Institute indicate elevated levels of CyanoChlorophyll (blue green algae). This week we had our highest blue-green cyano level of the 2020 season, from a sample taken just north of Vine Valley (see photo). Below are the results from samples collected this week.

How to interpret these results:

  • The values in this table are reported in ug/L, which is micrograms per liter.

  • DEC threshold for a bloom is 25 ug/L of CyanoChlorophyll (blue green algae).  

These results are telling us that these isolated blooms must be avoided. These particular blooms were not tested for toxins; however, based on previous data collected we know that Canandaigua Lake blooms with high levels of blue green algae may also have high levels of the microcystin toxin. Exposure to blooms and toxins can cause symptoms such as diarrhea, nausea or vomiting; skin, eye or throat irritation and allergic reactions or breathing difficulties. 

The six Canandaigua Lake water purveyors (the City of Canandaigua, the Village of Newark, the Village of Palmyra, the Village of Rushville, the Town of Gorham, and Bristol Harbour) continue with their routine testing of the public drinking water for the presence of toxins associated with harmful algal blooms. So far there have been no detectable levels of toxin in the finished drinking water. Results from routine sampling can be viewed here:

We thank you all for your continued support and ongoing efforts to help us monitor and protect the lake. We hope you will check out the tips below for ways you can help keep nutrients out of the lake when doing that fall cleanup around your property in the coming weeks. Remember, excess nutrients may fuel algae blooms and aquatic plant growth! Homeowners are all stakeholders in our watershed health, so let’s do our part to reduce our collective impact. Our watershed will thank us.




More Information on Blue Green Algae

Click below for our Harmful Algae Bloom brochure.

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