Berkeley's Lake Anza, in Tilden Regional Park, has been closed due to the presence of toxic algae, according to the East Bay Regional Park District.
Tilden Park remains open, but the swim lake is closed until further notice. The district's other swimming lakes and lagoons will remain open, however, including Quarry Lakes, Lake Temescal, Lake Del Valle, Cull Canyon, Contra Loma and Don Castro.
The algae causes rashes, skin and eye irritation, allergic reactions and gastrointestinal problems, according to park officials and the state Department of Health.
The algae can also be fatal for dogs, and dog owners are advised to avoid letting their pets come into direct contact with affected waters.