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WATER QUALITY UPDATE for July 23, 2021

Welcome to your Friday Water Quality Update. This week, we are happy to report there were no blooms observed by volunteers or watershed staff.

Since last week's edition, we have experienced some intense rain events across the Finger Lakes. These rain events have flushed an abundance of duckweed and watermeal from the West River and other tributaries, which can easily be mistaken for a harmful algae bloom (HAB). See photos below.

Duckweed and watermeal (Lemna spp. and Wolfia spp., respectively) are tiny floating aquatic plants that are among the smallest flowering plants on earth. They are native to our local ecosystem, and can proliferate rapidly. Often, the two species will be found together on the water’s surface, and may clump together or form into long “streaks”. These streaks can sometimes be observed in large swaths running down the length of the lake. Prevailing winds may also push duckweed and watermeal into coves or along shorelines and can easily be mistaken for a HAB, especially when observed from a distance.

Duckweed and watermeal do not produce toxins and are not harmful to human or pet health. However, during HABs season, we may sometimes see these aquatic plants mixed in with a harmful algae bloom. In that case, they should be avoided. 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 our Watershed Program Manager, Kevin Olvany, at the Canandaigua Lake Watershed Council. We may be able to assist with identification though a clear photograph.

As we know, conditions can change rapidly, and there is potential for increased cyanobacteria concentrations when the conditions are right. Please use your visual indicators to look for signs of active blooms. As recommended by the DEC, if you see it, avoid it. Volunteers and watershed staff will be continuing daily observations throughout July, August and September 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. To report suspicious blooms, use Enjoy your weekend!


More Information on Blue Green Algae

Click below for our Harmful Algae Bloom brochure.

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