BEACH Program

Swimming Standard and Marine Water Quality

The BEACH Program collects fecal bacteria data each year from Memorial Day through Labor Day and at selected beaches throughout the winter.

Saltwater Recreational Swimming Standards

enterococcus bacterial test photo by Eric Khambatta

Currently, the BEACH Program’s water quality decision criteria are based on EPA’s Ambient Water Quality Criteria for Bacteria - 1986 (PDF), not the Washington State Water Quality Standard for fecal coliform.

The fecal indicator enterococci is used, because this indicator better correlates with swimming-related illness than other fecal indicators, like fecal coliform or E. coli.

The saltwater swimming criteria is in two parts:

  • The geometric mean* shall not exceed 35 enterococcus/100 mL; based on results from a minimum of five weekly samples.
  • The enterococcus maximum should not exceed 276 enterococcus/100 mL.

If either of these criteria is exceeded, the beach should be CLOSED to swimming.

To be protective of swimmer health, BEACH also uses a Beach Action Value. If enterococcus levels exceed 104 enterococcus/100 mL then a beach ADVISORY is issued.

Find Swimming Beach Closures and advisories through our map-based application, or go straight to the long-term BEACH data.

*The geometric mean and maximum value concentrations are based on the arithmetic average of the three samples collected at a single beach for the day.