Drinking Water and HABs

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Click the icon to see public drinking water test results for Canandaigua Lake.

Cyanobacteria, also known as blue-green algae, naturally occur in surface waters. Under certain conditions such as warmer water temperatures, increased nutrients (primarily nitrogen and phosphorus), and calm water conditions,  cyanobacteria are able to grow rapidly, producing “blooms” referred to as harmful algal blooms or HABs.

HABs can produce toxins known as cyanotoxins, which can be harmful to humans and animals. Conventional water treatment (consisting of coagulation, sedimentation, filtration and chlorination) can generally remove intact cyanobacterial cells and low levels of cyanotoxins from source waters. However, public water systems may face challenges in providing drinking water during a severe bloom event when there are high levels of cyanobacteria and cyanotoxins in our lakes.

Private water system users (residents that are not hooked up to a municipal water supply) should educate themsleves on how to identify HABs and stay informed on current lake conditions to reduce their risk of exposure.

Know it.

  • HABs may look like green parallel streaks on the water surface, or have a spilled paint or pea soup appearance. Check out the DEC webpage to learn how to ID HABs.

Avoid it. 

Report it. 

  • If you think that a bloom may be harmful and is present on Canandaigua Lake, take a photo and report it to HABs@canandaigualakeassoc.org. Please include the location where the photo was taken. Public reports assist in the ongoing monitoring activities on the lake.


Frequently Asked Questions

HABs: Understanding the Risks of Piping Surface Water into Your Home.

HABs: Understanding the Risks of Piping Surface Water into Your Home.

How is the public drinking water being monitored?

  • 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 Geneva District Office of the Health Department and the New York State Department of Health to monitor the public drinking water for the presence of toxins associated with harmful algal blooms. Samples of the public drinking water are routinely collected and sent to a State approved laboratory on a regular basis during the harmful algal bloom season to determine if toxins are present. Results can be found here.

What are the health advisory levels for cyanotoxins in drinking water?

  • In June 2015, the U.S. EPA issued 10-day Drinking Water Health Advisories for the cyanotoxins microcystin and cylindrospermopsin.  This level has been set 1000 times lower than the anticipated level of human impact.  The EPA recommended health advisory levels are shown below.

 U.S. EPA Cyanotoxin Health Advisory Levels

Cyanotoxin Children, <6 years old School Age/Adult
Microcystin(s) 0.3 µg/L (ppb) 1.6 µg/L (ppb)
Cylindrospermopsin 0.7 µg/L (ppb) 3.0 µg/L (ppb)

If toxins associated with harmful algal blooms are in the public drinking water, is the water safe to drink?

  • The New York State Department of Health in cooperation with the affected public water system will notify the public when alternative water should be used for drinking, making infant formula, making ice, brushing teeth and preparing food.
  • The New York State Department of Health in cooperation with the affected public water system will issue necessary advisories for drinking water if levels exceed normal limits. The Canandaigua Lake Watershed Association is working with the water purveyors, the Canandaigua Lake Watershed Council, and the DOH to assist in getting the word out in the event that an advisory is issued. Please sign up for our email blasts to receive this information straight to your inbox.

What could the effects on my health be if I drink public drinking water with toxins associated with harmful algal blooms above the levels set by the EPA?

  • Symptoms such as vomiting, nausea, diarrhea, skin, eye or throat irritation, allergic reactions or breathing difficulties may occur after drinking water with elevated levels of toxins associated with harmful algal blooms. These symptoms are very similar to symptoms from other gastrointestinal illnesses or allergic reactions. Stop drinking the water and seek medical attention if you or a family member experience these symptoms.
  • Gastroenteritis which may include diarrhea, vomiting, and abdominal pain, and liver and kidney damage have been reported in humans following short-term exposure to toxins associated with harmful algal blooms in drinking water. However, more research is needed to fully understand the health effects.

I’m pregnant (or planning to be). Will consuming the public drinking water toxins effect my unborn child?

  • There is limited information available in the scientific literature on the potential for health effects from ingesting microcystin, the primary toxin associated with Harmful Algal Blooms, during pregnancy.
  • The New York State Department of Health will advise pregnant women not to drink the water if levels exceed normal limits.

If I live near a lake experiencing a harmful algal bloom, is my private well water safe to drink, bathe, wash dishes, etc.?

  • If a private well is a properly installed drilled well, it is unlikely to be impacted by Harmful Algal Blooms present in the lake. If the well is a shallow well installed along the shore of a lake experiencing a harmful algal bloom, toxins associated with the bloom may be present in the well water. In-home treatments such as boiling, disinfecting water with chlorine or ultraviolet (UV), and water filtration units do not remove the toxins associated with harmful algal blooms. There are treatment units on the market that have been shown to reduce microcystin levels in water, but it is not known if the microcystins would be reduced to a level considered safe. Since individual water supplies are not regulated or monitored, it is not known if there is a health risk to drinking the water from your private well.

If I draw my water directly from the lake experiencing a bloom, is my water safe to drink, wash dishes, etc.?

  • Never drink untreated surface water, whether or not harmful algal blooms are present. Even if the water is treated by in-home treatment units, DO NOT DRINK water drawn directly from the lake and DO NOT USE the water for making infant formula, making ice, brushing teeth, preparing food, and washing dishes when blooms are present. In-home treatments such as boiling, ultraviolet radiation (UV), and water filtration units do not remove the toxins associated with harmful algal blooms. There are treatment units on the market that have been shown to reduce microcystin levels in water, but it is not known if the microcystins would be reduced to a level considered safe. Since individual water supplies are not regulated or monitored, it is not known if there is a health risk to drinking the water from your private water supply.

Can my children and pets play in the lake water if it is experiencing a harmful algal bloom?

  • People, pets, and livestock should avoid contact with water that is discolored or has floating scum on the surface. If contact does occur, rinse the exposed skin thoroughly with clean water.
  • Exposure to harmful algal blooms can be deadly for pets, especially if they drink water with harmful algal blooms or when they lick their fur after swimming in waters with harmful algal blooms.

What health effects can I expect to see if I was recreating in lake water experiencing a bloom?

  • Recreational exposures can occur while swimming, wading, fishing, or boating in areas with harmful algal blooms if this water is touched or swallowed, or when airborne droplets are inhaled. Exposure to harmful algal blooms can cause diarrhea, nausea, or vomiting; skin, eye, or throat irritation; and allergic reactions or breathing difficulties. Seek medical attention if you experience these symptoms after exposure to harmful algal blooms.
  • The Department of Health The New York State Department of Health (NYSDOH) and Department of Environmental Conservation (NYSDEC), in collaboration with local health departments (LHDs), lake associations, and educational institutions, collect information on HABs and HAB-associated illness to help prevent further illnesses and improve understanding of how HABs affect human health, animal health and the environment.  When reporting illness symptoms to your local health department or NYSDOH, all the information you provide is kept strictly confidential and is used only for the purposes of investigation. Please report your symptoms to the Ontario County Health Department.

Have any health problems been reported by people after recreating in water bodies experiencing harmful algal blooms?

  • According to the New York State Department of Health, generally there have been infrequent reports of illnesses associated with recreational exposure to harmful algal blooms, and most of illnesses reported were minor. Since the symptoms from harmful algal bloom exposure are very similar to symptoms from other gastrointestinal illnesses or allergic reactions, we expect that bloom-related illnesses are under-reported.

What health effects may my pet experience if they were exposed to harmful algal blooms?

  • Symptoms for animals include vomiting, diarrhea, loss of appetite, excessive salivation or drooling, stumbling, seizures, convulsions, paralysis, disorientation, inactivity, excessive tiredness, fast heart rate and difficulty breathing. Seek veterinary care if your pet experiences these symptoms after exposure to harmful algal blooms.

What do harmful algal blooms look like? How will I be able to identify these blooms if I am on the lake?

  • Discolored water, often with a paint-like appearance, with or without floating scum or mats may be evidence of a Harmful Algal Bloom. Pictures of Harmful Algal Blooms can be found here: www.dec.ny.gov/chemical/81962.html
  • It is hard to tell a Harmful Algal Bloom from other non-harmful algae blooms. Therefore, you should avoid wading, swimming, boating, and fishing in waterbodies that are discolored or has scum or floating mats present.

What should I do if I see a Harmful Algal Bloom on Canandaigua Lake?

  • If you think that a bloom may be harmful and is present on Canandaigua Lake, take a photo and report it to HABs@canandaigualakeassoc.org. Please include the location where the photo was taken.
  • CLWA and the Canandaigua Lake Watershed Council are working in partnership with the NYS Department of Environmental Conservation and the Finger Lakes Institute on the Canandaigua Lake Shoreline HAB Monitoring Program. Routine shoreline monitoring is performed in an effort to better inform the public during HAB events on the lake.  Please sign up for our email blasts to receive water quality updates during HABs season.