Historical Water Quality
Passed water quality tests at least 95% of the time
This status is based on the latest sample, taken on July 31st, 2025 Swim Guide - Main updates the status of this beach as soon as test results become available. These results were posted to Swim Guide on July 31st, 2025 at 9:42.
Crown Memorial State Beach - Crab Cove is sampled Bi-Weekly from January 1st to December 31st.
About Crown Memorial State Beach - Crab Cove
Source Information
The East Bay Regional Park District’s recreational water quality is monitored as a collaborative effort between East Bay Parks, Contra Costa and Alameda County Departments of Environmental Health. Sites are monitored weekly from April - October and many continue to be monitored twice a month from November - March. Samples are tested for levels of total coliform, fecal coliform and enterococcus. During the peak season beaches are posted based on a singe sample maximum level and the geometric mean. Outside of the peak season, East Bay's coastal beaches are posted based on daily maximum levels only. The standards for indicator bacteria are as follows: Single sample maximum Total Coliform > 10,000 MPN (Most Probable Number) / 100 ml of water Fecal Coliform > 400 MPN / 100 ml Enterococcus > 104 MPN / 100 ml Geometric Mean (5 samples collected over a 30 day period) Total Coliform > 1,000 MPN / 100 ml of water Fecal Coliform > 200 MPN / 100 ml Enterococcus > 33 MPN / 100 ml A coastal beach is marked Green when bacteria levels for a single day and geometric mean are below the standards mentioned. A coastal beach is marked Red when bacteria levels for a single day or the geometric mean are above the standards mentioned. In Swim Guide, a red icons will be assigned to beaches posted with a cautionary advisory as well as emergency closures. East Bay monitoring agencies do not close beaches unless there is a sanitary sewer overflow or other emergency. Beach are posted with a yellow icon on East Bay’s website when bacteria levels are above the standards mentioned. A beach is marked Grey when there is no current or reliable monitoring information available. When visiting a beach, EB Parks encourages you to protect your health. 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 or swim within 100 feet of a flowing storm drain. Check posted signs for water quality information.
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