Water quality advisory issued for Lake Samish private drinking water systems

BELLINGHAM, Wash. — Whatcom County Health and Community Services (WCHCS) issued a water quality advisory on Tuesday, July 28, 2026, for residents using private drinking water systems drawing directly from Lake Samish.

According to WCHCS, a surface water test on the east shore of Lake Samish detected increased levels of microcystin, a cyanotoxin produced by blue-green algae.

The microcystin levels exceed safe drinking water limits for vulnerable groups. Vulnerable groups include infants, children under 6 years old, pregnant or nursing individuals, people with weakened immune systems, elderly individuals and people with liver disease. Test results showed levels remain safe for healthy adults and children over 6 years old.

WCHCS stated current microcystin levels remain safe for swimming and recreational water activities.

Residents with water intakes near algae blooms whose filtration systems are not confirmed to remove cyanotoxins are advised to follow the following guidelines while blooms are present.

vulnerable groups should not use the water for drinking, cooking, boiling, or brushing teeth
water should not be used to prepare infant formula
alternative water sources such as bottled water should be used for drinking
pets and livestock should be kept out of affected water

Bathing and handwashing remain generally safe for all groups at current levels, according to WCHCS.

WCHCS is sending notices to lakeshore residents and collecting water samples in response to bloom reports. The exact spread and duration of the cyanotoxin are unknown.