Lake Anza | Tilden Regional Park

Water Quality Conditions
 • Current Water Quality Conditions Report [PDF]

Lake Anza is tested for bacterial levels weekly from April to October. The map below indicates the sample sites on the beach. The East Bay Regional Park District works with the Alameda County Environmental Health Department in accordance with California Department of Public Health's Guidance for Fresh Water Beaches to determine water quality at Lake Anza. Our stop light sign is used to display the relative water quality from our latest bacteriological tests and cyanobacteria (blue-green algae) conditions. Cyanobacteria signage and designations are posted below our bacteriological result designations.

Water Quality Stop Light Designations:

Water safety indicator

Please be advised there is always some level of risk when swimming in any water body. To have a fun and safe experience swimming in the parks, we encourage you to follow a few simple rules:

  • Keep water out of your mouth
  • After you leave the water, shower and towel dry as soon as possible 
  • Do not swim in the lake for 3 days after a rainstorm
  • Check posted signs for water quality information

For more information contact the East Bay Regional Park District Water Management Department at (510) 544-2328

• Water Resources   • Lake Anza | Tilden Regional Park   • Lake Anza Swim Facilities