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Mason County annual BEACH report

Four beaches in Mason County were sampled during 2016. They were:

  • Allyn Waterfront Park
  • Potlatch State Park
  • Twanoh State Park
  • Walker County Park

All Mason County beaches met swimming standards. However, Walker County Park beach has a permanent swim advisory due to a nearby sewage outfall. Details on each beach are presented in the text below.

Twanoh State Park Beach in Mason County

Keeping beaches safe

The Beach Environmental Assessment, Communication & Health (BEACH) Program ensures that marine water is safe to swim and play in and informs the public if water doesn't meet swimming standards.

During the 2016 beach season, 61 public beaches on coastlines were sampled from Memorial Day through Labor Day. High-use beaches were sampled weekly or biweekly for enterococcus, a type of fecal bacteria. High enterococcus levels are linked to swimmer illness.

Mason County swimming beaches

We monitored four beaches in Mason County from May 23 through Aug. 30, 2016. All beaches were sampled weekly except for Walker County Park beach, which was sampled every other week. Details on each beach are presented in the text below.

Allyn Waterfront Park beach

During the 2016 swim season, Allyn Waterfront Park beach had excellent water quality. This beach met the swimming standards for all periods sampled. Bacteria levels at this beach have been improving since 2013.

Potlatch State Park beach

Potlatch State Park beach had very good water quality. This beach met the swimming standards for all periods sampled.

Twanoh State Park beach

The Twanoh State Park beach is heavily used during the summer months. During the 2016 swim season, this beach had very good water quality. Twanoh State Park beach met the swimming standards for all periods sampled.

Walker County Park beach

Walker County Park beach was sampled every other week during the swim season. This beach has a permanent swim advisory due to proximity to a sewage treatment plant outfall. However, Walker County Park had the best bacterial water quality of all 61 beaches sampled for the Washington BEACH Program in 2016. Bacteria levels were low at this beach, meeting swimming standards during all periods sampled.

Data summary: Bacteria results compared to standards

The chart below summarizes the bacteria levels in these four beaches in relation to the EPA swimming standard:

  Geometric Mean 90th Percentile
EPA Swimming Standard ≤ 35 ≤ 276
Allyn Waterfront Park 16 29
Potlatch State Park 11 19
Twanoh State Park 10 15
Walker County Park 9 9