Interior Health lifts Williamson Lake algae bloom advisory

Williamson’s Lake is a popular swimming hole located inside city limits that is open to the public. Photo: Aaron Orlando/Revelstoke Mountaineer

Interior Health has lifted its algae bloom advisory for Williamson Lake as of July 20, 2022.

In a statement issued July 21, Interior Health said the water is clear and their is no signs of an algae bloom. The conditions have changed in the past days. On July 19, Interior Health said it was still monitoring conditions on the lake: “The latest observations indicate an algae bloom may still be present,” it wrote in a statement sent to local media.

Williamson Lake pictured on July 2, 2022, with an unusual green and cloudy hue. Photo: Aaron Orlando/Revelstoke Mountaineer Magazine

In response to questions from, Interior Health (IH) said that a sample taken on July 15 was tested. “A sample, from July 15, was analyzed for algal toxins and confirmed an absence of toxins,” IH said in a statement.

The health authority said it does not test to see if an algae bloom is present, but does test to see if toxins that can be generated by algae blooms are present. There are many different kinds of algae blooms and some can produce toxins. Find out more about algae blooms on this B.C. government website, Algae Watch.

New advisory signs about a potential algae bloom at Williamson Lake were posted on July 8, 2022. Photo: Aaron Orlando/Revelstoke Mountaineer Magazine

IH issued general advice on algae blooms in May. In a May 2 information release, it said, “Blue-green algae or Cyanobacteria can produce several types of toxins that can be poisonous to people, pets or livestock. Cyanobacteria blooms often cause the water to look bad and may also smell bad.

“Two of the most important ways to reduce the risk is to rinse off with clean water after swimming and do not consume lake water.”

Interior Health also advised people to take the four following precautions:

-If there is a bloom always use caution. Avoid all direct contact with a bloom. If contact is made, it is important to rinse your body with clean water.

-If you see a bloom recreational activities are discouraged, such as swimming.

-Consider using an alternate source for drinking water, if the bloom is in your drinking water source. Boiling the water will not remove any toxins. Contact your water supplier for more information.

-Consider providing pets and livestock with an alternate source of drinking water.

It also advised people to see a health care provider if you are showing any of the following symptoms and believe they may be from exposure to cyanobacteria:

Headaches, nausea, fever, sore throat, dizziness, stomach cramps, diarrhea, abdominal pain, vomiting, muscle aches, mouth ulcers, blistering of the lips, rashes and irritation of the ears and eyes.

IH encourages people to report algae blooms online through BC Algae Watch, a provincial algae reporting and information website.

Testing for Williamson Lake?

One of several algae bloom advisory signs posted at Williamson Lake on July 8, 2022. Photo: Aaron Orlando/Revelstoke Mountaineer Magazine

Our initial reporting found the City of Revelstoke does not participate in an Interior Health program that monitors swimming area water quality and tests for E. coli and toxins created by algae blooms. Local governments that participate in the program perform regular testing and the results are posted on an Interior Health website that is regularly refreshed with up-to-date testing results, including E. coli levels.

City issues algae bloom advisory for Williamson Lake, questions reveal no regular water quality monitoring at popular city swimming spot

Participation in the program also leads to algae bloom advisories that are listed on this webpage.

Participation in the testing program is not mandatory.

Local governments that participate in the program are first required to create what is called a “beach safety plan.” The plan requires the municipality to catalogue a wide range of physical and biological hazards. Find out more about beach safety plans on this IH website.

The detection of algae blooms can lead to different kinds of advisories. A “cautionary” advisory results when no testing has been done or if testing has been done and has not identified toxins.A “do not use/beach closure” advisory results when testing has been done and toxins have been detected. has asked follow-up questions to Interior Health to see what the plan is moving forward for testing on Williamson Lake. We will post an update at the end of this story when a response is received.

The City of Revelstoke first announced the algae bloom in a July 8 Facebook post, saying it was a precautionary measure. It also posted signage at the lake on Friday, July 8. Testing was not done until after the weekend.

Interior Health later posted it as a cautionary advisory to their bloom advisory website. The algae bloom had been visible since at least July 2 and was the source of dialogue in the community.


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