Gibbs Lake Closed Due To Toxin

Contact: Michael Dawson, Water Quality Manager, Jefferson County Public Health

(360) 385-9444 ext. 301

High levels of the toxin microcystin were detected in a water sample taken from Gibbs Lake on Monday, July 19. The toxin level is 46 micrograms per liter, which is more than five times above the Washington State recreational criteria of 8 micrograms per liter.

Microcystin is produced by cyanobacteria, also known as bluegreen algae, and can result in illnesses in people and animals. As a result, Jefferson County Parks and Recreation has closed the lake for swimming, boating and fishing. Visitors are also urged to keep pets out of the water. Jefferson County Public Health (JCPH) has posted Danger signs at lake access points and signboards. The rest of Gibbs Lake County Park remains open for hiking, biking, and horseback riding.

JCPH has monitored local lakes for cyanobacteria seasonally since 2007. Monthly monitoring of Anderson, Gibbs, and Leland lakes began in April of this year. Anderson Lake closed in May due to high levels of anatoxin-a, another toxin produced by cyanobacteria. Low concentrations of microcystin and no anatoxin-a were detected in Lake Leland on July 6. Lake conditions can change rapidly and lake status can change between samples. JCPH urges recreationists to avoid contact with heavy blooms or scums. If you observe a bloom in a Jefferson County lake, please report it by calling (360) 385-9444.

To check the status of Jefferson County Lakes and learn more about toxic cyanobacteria monitoring, consult the JCPH website at or call (360) 385-9444. For fishing seasons and regulations see the Washington Department of Fish and Wildlife website Information on visiting Gibbs Lake County Park is available at