Surface Water Management Division

Toxic Algae Bloom Alert

Last updated 11/2/2009

Lake Cassidy - November 2009 - Toxins Still Detected but Much Lower Values

Picture of Lake Cassidy Algae Bloom

Lake Cassidy has been experiencing a significant bloom of blue green algae starting sometime between August 12th and 19th.  The bloom can turn the water bright green or blue and can form scums that look like green paint floating on the water's surface.   Blue-green algae (also known as cyanobacteria) also have the potential to produce toxins.

Water tests from 9/8/2009 through 10/19/2009 show that one toxin (microcystin) was present at levels significantly higher than the Washington State Department of Health's recreational standard of 6 parts per billion (see specific results below).  Therefore, a WARNING sign was placed at the lake's public access sites.  The sign indicates that toxic algae may be present and recommends that residents do not swim or water ski, do not drink lake water, keep pets and livestock away, clean fish well and discard guts, and avoid areas of algae scum when boating. Testing on 10/26 & 11/2/2009 have shown microcystin levels are decreasing, but still present.  The signs will be remain up until toxin levels have not been detected for two consecutive weeks.  Toxic algae can cause serious illness in humans who drink or play in affected waters. Toxic algae exposure can also kill pets, waterfowl, and other animals.  Call your doctor or veterinarian if you or your pet has unexplained sickness or signs of poisoning.    For more information refer to our Toxic Algae page or visit the State Department of Health website.   For health related inquiries you may also call the Snohomish Health District at 425-339-5250. To sign up for toxic algae email alerts email Marisa Burghdoff.  WARNING sign posted at Lake Cassidy - click to enlarge       Test Date Microcystin(parts per billion)  Anatoxin (parts per billion) Above Recreational Standard of 6 ppb 8/19/2009 Not Detected Not Detected No  8/24/2009 Not Detected Not Detected No 9/3/2009 Not Detected Not Detected No 9/8/2009 52.2 Not Detected YES 9/15/2009 30.7 NA YES 9/21/2009 665 Not Detected YES 9/29/2009 178 NA YES 10/5/2009 802 Not Detected YES 10/12/2009 413 NA YES 10/19/2009 4600 Not Detected YES 10/26/2009 0.909 NA No 11/3/2009 Between 3 and 6 NA No

Contact

Gene Williams, Senior Planner, 425-388-3464 extension 4563

Marisa Burghdoff, Water Quality Analyst, 425-388-3464 extension 4639

 

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