BEACH Program

2016 BEACH Program Report

Mason County

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

Bacteria Results Compared to Standards 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

Allyn Waterfront Beach Park

Allyn Waterfront Beach Park

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

During the 2016 swim season, Potlatch State Park beach had very good water quality. This beach met the swimming standards for all periods sampled.


Twanoh State Park Beach

Twanoh State Park Beach

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.

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