Surface Water Management Division

Toxic Algae Bloom Caution

Last updated 10/15/2009

Lake Ketchum - Summer/Fall 2009

Example of scum from blue-green algae bloom.

Lake Ketchum has been experiencing a significant intermittent bloom of blue green algae since early June.  The bloom looks like green paint floating on the surface and sometimes breaks up into small algal clumps in the water column.  It has been intermittent and is largely composed of the species Anabaena.  This type of algae is capable of producing anatoxin-a, a neurotoxin.  The other major species present has been Microcystin, a species capable of producing microcystin, a liver toxin has also been found.  If present, 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.

Toxic algae monitoring has occurred on a weekly basis in 2009.  Samples are taken when blooms are present.  So far in 2009, anatoxin and microcystin levels have not been found above the recreational standard  of 1 part per billion for anatoxin and 6 parts per billion for microcystin.  The recreational standards were set by the Washington State Department of Health.  A complete list of test results to this date are listed below.     Since it is not known what causes algae to begin producing toxins, a CAUTION sign has been placed at the public access site.  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. The signs will be remain up until the bloom of potential toxin producing algae dissipates.  If test results find toxin levels above the recreational standards, "WARNING" signs indicating that toxic algae is present will be posted and residents will be notified via email alerts.  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.   CAUTION sign posted at Lake Ketchum - click to enlarge

Test Date	Anatoxin parts per billion	Microcystin in parts per billion	Above Recreational Standard
6/14/2009	Not Detected	<0.5	NO
6/30/2009	Not Detected	NA	NO
7/14/2009	Not Detected	<0.5	NO
7/21/2009	Unable to analyze	0.194	NO
7/29/2009	Not Detected	0.0815	NO
8/11/2009	Not Detected	0.0845	NO
8/19/2009	Not Detected	NA	NO
8/24/2009	Not Detected	0.0855	NO
9/2/2009	NA	<0.5	NO
9/8/2009	Not Detected	0.11	NO
9/21/2009	Not Detected	0.174	NO
10/5/2009	Not Detected	0.203	NO

Contact

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

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

 

Some of these documents are in pdf format. To read these files you'll need to have Adobe Acrobat Reader installed on your computer.