A bloom of toxic blue-green algae recently forced the closure of three East Bay lakes to swimmers. Quarry Lake in Fremont, Del Valle in Livermore, and Shadow Cliffs in Pleasanton are all off-limits to people and pets due to the dangerous water conditions, per ABC 7.
The East Bay Regional Parks District has posted signs at the lakes warning people to avoid contact with the water. A less severe caution advisory has been issued for Lake Temescal in Oakland, Lake Anza at Tilden Park in Berkeley, and Contra Loma Reservoir in Antioch.
Blue-green algae, also known as cyanobacteria, are natural organisms that tend to bloom in areas with low water levels, warm temperatures, and stagnant water. These conditions can cause the algae to release toxins that can be harmful to people and animals, per the San Francisco Chronicle.
According to the California Department of Public Health, exposure to toxic algae can cause skin and eye irritation, allergic reactions, and in severe cases, serious illness or even death, per Patch. Several dog deaths in California in recent years have been linked to toxic algae blooms.
The first toxic algae blooms in the East Bay Regional Parks District occurred during the drought year of 2014. Since then, the district has implemented a comprehensive monitoring program to ensure the safety of the water in its reservoirs.
Officials are urging park visitors to follow the recommendations on the posted signs. If you see a bloom, stay away from areas with foam, scum, or algae mats, and keep pets away from the water. People and animals should not consume water with cyanobacteria, even if it is boiled or filtered.
If you or your pets come into contact with cyanobacteria, rinse with fresh water immediately, monitor for unusual symptoms, and seek medical treatment if symptoms occur.
The status of the lakes can change frequently, so visitors are advised to check the district's water quality webpage before planning a visit.