Toxins from algae bloom on Canandaigua Lake force drinking ban in Rushville

Toxins generated by blue-green algal blooms in Lake Canandaigua have infected the public drinking water in the Village of Rushville, which draws its raw water from the lake about four miles to its west, test samples show.

The state Department of Health yesterday urged all customers who rely on the village’s water system and those in the nearby Middlesex Water District to halt use of public water for drinking, cooking and making ice until further notice.

“The state is handling the whole thing, bringing in bulk water from outside,” John Sawers, mayor of Rushville, population 672, told WaterFront today. “We’re sampling like crazy. We expect further results within 24 hours.”

Drinking water samples are being sent daily to the DOH’s Wadsworth Lab in Albany. Meanwhile, the health department has provided containers or bottles of water to two affected schools in Rushville and to the Rushville Hose Company for distribution to residents.

Boiling tap water does not rid it of the dangerous toxins, which affect the nervous system.


Canandaigua and all 10 of the other Finger Lakes have been plagued in recent years by blooms of blue-green algae, or cyanobateria, which produce toxic chemicals such as microcystin. 

Many towns in the region began testing their public drinking water after the city of Toledo, Ohio, banned 500,000 people from drinking from its public system in 2014 due to toxins caused by an algal bloom on Lake Erie.

Syracuse, Auburn, Owasco and other Finger Lakes towns that draw raw water from Owasco and Skaneateles lakes have had their own public drinking water scares since 2016. But tests of samples this year hadn’t triggered any known drinking water advisories before Rushville received its Oct. 11.

The DOH did not immediately respond to questions submitted by WaterFront.

In a statement issued Oct. 11, the DOH said tests results showed 0.66 micrograms per liter of microcystin in Rushville’s finished water. That level is more than twice the U.S. Environmental Protection Agency’s 10-day health advisory level of 0.3 micrograms for children under 6 years old. The EPA advisory level for others is 1.6 micrograms.

“Out of an abundance of caution, the state is recommending to all consumers that they not consume water at this time,” the DOH said in its statement.

Sawers said an earlier test result for Rushville water showed 0.56 micrograms per liter. He said it was the second consecutive reading above the 0.3 microgram threshold that triggered the DOH warning not to drink the water.

Sawers added that he understood that several other nearby communities had also received individual results above 0.3 micrograms per liter. He said he understood that the DOH had not issued drinking water advisories for those communities because of a lack of a confirming second high reading.

The state Department of Environmental Conservation tracks what it refers to as harmful algal blooms, or HABs, and it maintains and updates a HABs notification page on its website.


Roughly 100 waterbodies across the state are listed on an agency chart that classifies blooms as “suspicious,” “confirmed” and “confirmed with high toxins.” It is a challenging task to keep the chart up to date because blooms are not always reported immediately and they are often very short-lived.

Blooms that produce 4 micrograms per liter (parts per billion) of microcystin, the most common algal toxin in the Finger Lakes, triggers the DOH to ban swimming in the area.

Blooms that produce five times that level of microcystin (20 micrograms per liter) are classified as “high toxin.”

Seneca, Cayuga and Owasco lakes were particularly hard hit by “high toxin” events last month. Local watershed websites show that Seneca had 26 blooms with laboratory-confirmed high toxins this year — mostly in September — while Cayuga had at least 13 and Owasco had at least five.

Outbreaks on those lakes in previous years stimulated the formation of groups of volunteer lake shore monitors who sample and take pictures of water showing suspicious signs. Blooms can appear as streaky wisps of green or as green swaths that look like spilled paint.

The volunteers work with the DEC through local groups such as Seneca Lake Pure Water AssociationCommunity Science Institute in Ithaca and Owasco Watershed Lake Association. Those groups post interactive maps on their websites, which show the location of blooms and their test results.

Gov. Andrew Cuomo has announced the commitment of $65 million to combat toxic algae and protect public drinking water statewide. He has designated 12 lakes — including five Finger Lakes (Conesus, Honeoye, Cayuga, Skaneateles and Owasco) — for concentrated focus.

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While the governor’s efforts have won praise, the DEC has come under fire for not doing enough to regulate large dairy farms that produce nutrient-rich runoff suspected of fueling algal blooms. 

Environmental groups sued the agency over what they characterized as lax permitting and oversight of farms, and they won in court. In April, a state Supreme Court judge in Albany ordered the DEC to revamp its permitting of mega-farms, spurring an ongoing controversy.

Meanwhile, other lawsuits allege that the state’s failure to require power plants on the shores of Seneca and Cayuga lakes to recycle cooling water also encourages algal blooms.

One affidavit by Gregory Boyer, a HABs expert in Syracuse, said algal blooms would be somewhat more likely in the Dresden bay area of Seneca Lake because the Greenidge power plant is allowed to discharge more than 100 million gallons per day of warmed, unrecycled water. That contributes to ideal conditions for algal blooms, Boyer contended.

SPLWA records show that five blooms “confirmed with high toxins” struck this season within a mile of the Keuka Outlet, where Greenidge’s warmed water empties into Seneca Lake. Three of those five blooms showed readings at least 10 times the DEC threshold for “high toxins.” 

Peter Mantius is the founder of the Water Front, an all-digital publication dedicated to providing news and coverage of important environmental news in the Finger Lakes. He brings decades of reporting and editorial experience to his reporting, which includes frequent deep-dives into local, and regional issues. Contact him by clicking here or dropping him a line at [email protected].

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