Mason County BEACH report
We sampled three beaches weekly in Mason County during the 2024 monitoring season:
- Belfair State Park
- Potlatch State Park
- Twanoh State Park
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. Sampling takes place from Memorial Day to Labor Day. During this time, you can check out current water quality conditions on the swimming map.
The Department of Ecology sampled three beaches weekly in Mason County during the 2024 season.
See details on each beach below.
Data summary: Bacteria results compared to standards
The chart below summarizes the bacteria levels at Mason County beaches in relation to the EPA swimming standard or saltwater swimming criteria. Beaches are considered unsafe for swimming when the geometric mean of enterococcus/100 mL of water is greater than or equal to 30 and the statistical threshold value of enterococcus/100 mL is greater than or equal to 110. We issue a public swimming advisory when enterococcus levels exceed 104 per 100 mL of water.
Table: Calculated geometric mean and statistical threshold value at Mason County beaches (in enterococcus per 100 mL) for 2024.
| Beach | GM | STV |
|---|---|---|
| Belfair State Park | 36 | 165 |
| Potlatch State Park | 12 | 21 |
| Twanoh State Park | 23 | 141 |
Contact information
Contact BEACH: Reach BEACH staff, sign up for our email list, or follow us on social media platforms.