The newly reopened swim areas are at these state parks: Silver Sands in Milford, Indian Well in Shelton, and Lake Waramaug in Litchfield County.
The three swim areas had been closed due to high bacteria levels.
The swim areas at Kettletown State Park in Southbury remain closed due to the presence of blue-green algae.
The state will conduct regular weekly testing of all 23 state park beaches later this week.
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