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Algal Alert Update

12 Oct 2021 9:57 PM | Anonymous member (Administrator)


I have just spoken to the staff member at the Ministry of Environment, Conservation and Parks (MECP) who did the water sampling of Kahshe Lake last week regarding the blue-green algal bloom that was documented in the East end of the lake. She has clarified a number questions I had as noted below:

  • When she investigated two of the reported algal blooms on October 4th, there wasn't any algal growth present, so she submitted a sample collected by the property owner for analysis at the MECP lab.
  • She received the results confirming the blue-green algal bloom and passed them on to the Simcoe-Muskoka Health Unit (SMHU), and they issued the Health Alert for the ENTIRE lake, as there had been a number of other reports of algal bloom development over the past couple of weeks.
  • She agreed to my request for more information and will send me the lab report with the algal species that were identified as well as the toxin analysis results.
  • She also said that she won't be re-sampling the lake for another 3-4 weeks, as the bulk of the toxins are typically released as the algae start decomposing.
  • As soon as the results from the resampling in November are in and show no evidence of toxins, the SMHU will be advised and they will remove the Alert from their website.
  • I'll keep you posted as I hear more, but for now, the health advice applies to the entire lake if a bloom is visible in the vicinity of your waterfront.
  • And I've now received the actual alert issued by the SMHU and it as well as some warning signs that need to be followed have been posted below.

Ron Pearson

Kahshe and Bass Lake Steward


  Media Coordinator

Public Service Announcement


FOR IMMEDIATE RELEASE                                                                       

                                                                                                  Media Desk

                                           705-721-7520 or 1-877-721-7520 (x 8533)                        Heather Howe (x7472)/Kara Thomson-Ryczko (x7417)


cautioned about blue-green algae bloom

Town of Gravenhurst - Residents and visitors to Kahshe Lake in the Town of Gravenhurst are being cautioned about a confirmed blue-green algae bloom impacting the lake.  

The Simcoe Muskoka District Health Unit is asking residents and visitors to exercise caution where blue-green algae is visible and to take the following precautions:

§  Do not use the lake water for the preparation of infant formula

§  Do not allow pets or livestock to drink or swim in the water where an algae bloom is visible

§  Be cautious about eating fish caught in water where blue-green algae blooms occur

§  Do not use herbicides, copper sulphate or other algaecides that may break open algae cells and release toxins into the water

§  Avoid swimming and other water sport activities where an algae bloom is visible.

Blooms may make the water look bluish-green, or like green pea soup or turquoise paint.

Many species of blue-green algae (also called cyanobacteria) have the potential to produce toxins that are harmful to the health of humans and animals. The Ministry of Environment, Conservation and Parks will be further analyzing samples to determine the presence of any toxins.

Symptoms from consuming toxins from a blue-green algae bloom can include headaches, fever, diarrhea, abdominal pain, nausea and vomiting, and can be more serious if water is swallowed in large quantities.

The health unit and the Ministry of Environment, Conservation and Parks will continue to work together to monitor the algal bloom and updates will be provided on our website ( as we receive new information.

To learn more about blue-green algae visit the health unit website at, or call Health Connection weekdays from 8:30 a.m. to 4:30 p.m. at 705-721-7520 or 1-877-721-7520.


Kahshe Lake Ratepayers' Association (1994) Inc. (KLRA)
PO Box 1318, Gravenhurst, ON, Canada, P1P 1V5
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