Gardner Lake State Park in Salem, Gay City State Park in Hebron and Kettletown State Park in Southbury are closed because of water quality, according to the Connecticut Department of Energy and Environmental Protection.
Indian Well State Park in Shelton is open, but warnings are posted because of blue-green algae.
The DEEP has reopened Wadsworth Falls State Park in Middlefield after getting results of water quality tests.
Test results are due Friday for Gardner Lake and Gay City.
More information about the closures can be found on the DEEP website by calling the DEEP at 866-287-2757.