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.
From Memorial Day through Labor Day in 2020, we sampled 63 public high-use beaches statewide, either weekly or biweekly, for enterococcus, a type of fecal bacteria. High enterococcus levels are linked to swimmer illness.
Mason County saltwater swimming beaches
We monitored three beaches weekly in Mason County from June 1 – Aug. 31, 2020.
Find details about each of the Mason County beaches below:
During the 2020 swim season, Belfair State Park had excellent water quality. This beach was sampled 14 times during the season and met the swimming standard during all periods sampled.
During the 2020 swim season, Potlatch State Park beach had excellent water quality. This beach was sampled 14 times during the season and met the swimming standard during all periods sampled.
The Twanoh State Park beach is heavily used during the summer months. During the 2020 swim season, this beach had one sampling event with elevated bacteria results. On June 29, results were in the advisory range, but subsequent samples showed bacteria levels dropped into the safe swimming range. Twanoh State Park beach was sampled 15 times during the season and met the swimming standards for all other periods sampled.
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 2020.
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Beach
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GM
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STV
|
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Belfair State Park
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11
|
17
|
|
Potlatch State Park
|
<10
|
10
|
|
Twanoh State Park
|
11
|
25
|
|