Caution Urged If Headed To Discovery Bay: Waters Tested Positive For Toxic Algae

CONTRA COSTA COUNTY, CA – Samples taken from the waters around Discovery Bay tested positive for microcystin, a toxin produced by certain algal species that can be harmful to people, animals, especially dogs, and livestock, according to laboratory results released today by the U.S. Environmental Protection Agency lab in Richmond.

Contra Costa Health Services’ Environmental Health Division and the California State Water Resources Control Board recommend that area residents avoid contact with Discovery Bay waters until further notice.

The community’s tap water is not affected and is safe to use, health officials said.

“We received multiple complaints from Discovery Bay, and we sampled those areas for blue-green algae. Test results indicate the presence of toxin and we’re asking the community to stay out of the water until further notice,” said Marilyn Underwood, director of CCHSEH.

"Caution" and "danger" signs are being posted in accordance with state guidelines.

“It is important for people to understand that sampling did not take place in all areas of Discovery Bay. Bloom conditions can change rapidly and we recommend minimizing contact with the water and algae in Discovery Bay,” said Beverley Anderson-Abbs, an environmental scientist with the State Water Board.

Health agencies warn against handling dried blue-green algae, removing algae from the water or attempting to treat the algae. Exposure to blue-green algae can cause rashes, skin and eye irritation, allergic reactions, gastrointestinal upset and other effects on people.

“Dogs are especially vulnerable to getting sick from exposure to toxic algae blooms, and there have been reports in the past of dogs dying after exposure to water with blue-green algae blooms,” said Anderson-Abbs.

A map of the areas sampled and their results is available online here or at cchealth.org along with information about blue-green algae.

“Microcystins were measured above state health-based trigger levels in eight of the 10 samples,” said Underwood. “Samples from Harbor Bay and three of the four samples taken from the southwest area had levels that exceed the danger level. Other areas sampled had levels that exceed the caution level or did not contain microcystin at a level of concern.”

State health officials, including the California Department of Public Health, the Office of Environmental Health Hazard Assessment, and the State Water Board, are working with local authorities to monitor the situation, authorities said.

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