Surface Water Management Division

Lake Cassidy Toxic Algae Bloom Alerts - Summer 2010

Last updated 11/24/2010

Lake Cassidy was monitored on a weekly basis through the summer and fall of 2010 for the presence of toxins  produced by blue green algae.  The toxins can potentially be harmful to people and pets that recreate in the lake.  Toxins are more frequently produced during algal blooms often seen at Lake Cassidy in the summer.  Blue-green blooms look like green paint floating on the surface or small clumps floating in the  water.  

WARNING sign posted at Lake Cassidy - click to enlarge

Lake Cassidy experienced significant blooms of blue green algae throughout September and most of October. Samples taken during that time contained the liver toxin microcystin at levels that exceeded the Washington State Department of Health's recreational standard of 6 parts per billion (ppb). Samples taken on October 25th and November 3rd showed toxin levels that were less than 1 ppb. After two consecutive weeks of toxin levels below the state standard, the WARNING signs were removed from the lake's public access points on November 16th. However, please continue to excercise caution, especially if an algae scum is present.    The Warning sign indicates that toxic algae is 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.

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.      Picture of Lake Cassidy Algae Bloom       Test Date Microcystin** ppb    Anatoxin*  ppb  Above Recreational Standard 6/07/2010  0.058 0.175 NO 6/14/2010 Not Detected Not Tested NO 6/21/2010 Not Detected Not Detected NO 6/28/2010 Not Detected Not Tested NO 7/7/2010 Between 1 and 6 ppb Not Tested NO 7/12/2010 Not Detected Not Detected NO 7/19/2010 Between 1 and 6 ppb Not Tested NO 7/26/2010 0.229 ppb Not Detected NO 8/4/2010 Between 1 and 6 ppb Not Tested NO 8/9/2010 0.37 ppb Not Detected NO 8/16/2010 Between 1 and 6 ppb Not Tested NO 8/23/2010 2.85 ppb Not Detected NO 8/30/2010 15.7 ppb Not Tested YES 9/7/2010 >6 ppb Not Tested YES 9/13/2010 732 ppb 0.0239 YES 9/20/2010 Not detected Not Tested NO 9/27/2010 >6 ppb at trail Not Detected YES 10/5/2010 62.9 ppb Not Tested YES 10/11/2010 116 ppb Not Detected YES 10/18/10 27 ppb Not Tested YES 10/25/10 0.118 Not Detected NO 11/3/10 4.21 Not Tested NO *Microcystin is a liver toxin and the WA State recreational standard is 6 parts per billion (ppb) **Anatoxin is a neurotoxin and the state recreational standard is 1 part per billion (ppb

Contact

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

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

 

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