Cyanobacteria (Blue-Green Algae) Updates

Notice
With the COVID-19 Shelter in Place mandate, all Park swim facilities are closed, but Park trails continue to be open to the public and safety around cyanobacteria issues continues to be a priority.  Park closure updates...
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Due to the drought and unusually warm weather conditions, toxic blooms of cyanobacteria (blue-green algae) and other water-quality issues are occurring more frequently in the East Bay Regional Park District and elsewhere. We monitor our lakes and shorelines regularly and post warnings and closures when appropriate. Here’s a current update of which lakes and shorelines are affected:

  • Lake Del Valle: Cyanobacteria (blue-green algae) is present in Del Valle Reservoir, and toxins have been detected. Avoid any contact with cyanobacteria or scums in the water, and keep dogs away from the lake. Swimming is not permitted due to COVID-19 restrictions.
  • Lake Anza (Tilden): Cyanobacteria (blue-green algae) is present in the lake, and toxins have been detected. Avoid any contact with cyanobacteria or scums in the water, and keep dogs away from the lake. Swimming is not permitted due to COVID-19 restrictions.
  • Lake TemescalCyanobacteria (blue-green algae) is present in the lake, and toxins have been detected. Avoid any contact with cyanobacteria or scums in the water, and keep dogs away from the lake. Swimming is not permitted due to COVID-19 restrictions.
  • Big Break: Cyanobacteria (blue-green algae) is present in the water, and toxins have been detected. Avoid any contact with cyanobacteria or scums in the water, and keep dogs away from the water.
  • Shadow Cliffs ArroyoCyanobacteria (blue-green algae) is present in the Arroyo, or back lakes area, but no toxins have been detected.  Keep dogs away from the water in the Arroyo.
  • Quarry Lakes: Cyanobacteria (blue-green algae) is present in the lake, and toxins have been detected. Avoid any contact with cyanobacteria or scums in the water, and keep dogs away from the lake. Swimming is not permitted due to COVID-19 restrictions.
  • Lake Chabot: Cyanobacteria (blue-green algae) is present in the lake, and toxins have been detected. Avoid any contact with the water and keep dogs away from the lake. Swimming is never permitted at Lake Chabot.

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