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Water Quality Update for September 3, 2021

So far this week:

  • 22 surveys performed

  • No Blooms reported

Welcome to your Friday Water Quality Update!

Current Lake Conditions

Through our monitoring network of Watershed Council and Association staff, Canandaigua Lake Watershed Association volunteers, and reports from the general public - we have had zero blue green algae (cyanobacteria) blooms this week. Overall, water clarity is holding in the 5.5- 6.0 meters as measured by a secchi disk, which is good for this time of year.

Since mid - August, we have also sampled open water levels of cyanobacteria ( blue green algae) on a weekly basis at nine locations in the northern third of the lake (historically the area with the highest open water concentrations). We have been trying to sample on days when we are getting reports of shoreline blooms and conditions are ripe for potential open water blooms. Results from our August 28th sampling showed blue green algae levels that ranged from 0.33-1.86 ug/L (micrograms per liter) with an average of 1.05 ug/L. The DEC threshold for a bloom is 25 ug/L. We also sampled at three of these locations for the microcystin toxin that can be produced by blue green algae. Two of the results were less than the 0.3 ug/L detection limit and one sample was 0.31 ug/L. The DOH threshold for re-opening a beach is less than 4.0 ug/L. We are very pleased with these results thus far. We will continue this sampling effort through early October.

Deep Run beach in the Town of Gorham, which is an Ontario County Park, was closed last weekend due to blue green algae. The NYS Department of Health tested the water quality of the beach on Monday, August 30th and the results indicated that the beach could be reopened. However, as with many of the other public beaches - lifeguard staffing issues may not allow Ontario County to re-open Deep Run. Please remember that if there is no lifeguard on duty, no swimming is allowed at public beaches.

Monitoring of Public Drinking Water Systems

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) are working alongside the New York State Department of Health to monitor the public drinking water for the presence of toxins associated with harmful algal blooms. Samples are collected of both raw (untreated) and finished (treated) water on a weekly basis for microcystin (the toxin that can be produced by blue green algae). All results to date have come back as undetectable. The water purveyors will continue to sample on a weekly basis through early October. Weekly results are posted on the CLWA website and can be found here.

For more infomation on drinking water and harmful algae blooms, the CLWA website has a list of Frequently Asked Questions which can be found here. This webpage also includes considerations for users of private water systems.

The above water quality observations and data are very promising this week. However, it is important to remember that conditions can change quickly on the lake. Typically, we have seen our most significant bloom events in the early to mid-September timeframe. Please use your visual indicators before entering the lake. Look for discolored water, surface streaking of blue green algae (cyanobacteria) or pea soup conditions.

If you have a question on a suspected bloom, please feel free to send in a photograph to This email address is monitored by CLWA and Canandaigua Lake Watershed Council staff. We may be able to assist with identification though a clear photograph.

Volunteers and watershed staff will be continuing daily observations throughout September and early October, and we will communicate any significant changes in bloom activity through our weekly email updates, on our websites, and on the Association's facebook page.

Enjoy Labor Day weekend and consider using LED flares for the Ring of Fire!


More Information on Blue Green Algae

Click below for our Harmful Algae Bloom brochure.

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