The Oshawa beaches have been posted due to elevated bacteria levels, according to Durham Region Health Department.
The health department tests all 14 beaches across the region on a weekly basis to test for elevated levels of E. coli.
Beaches are posted as unsafe for swimming when elevated levels of E. coli exceed the provincial standard of 200 E. coli per 100 mL of water.
There are six other beaches across the region that have also been posted, including Beaverton Beach South, Bowmanville Beach East and West, Newcastle Beach Central, Paradise Beach (formerly Pickering Beach), and Whitby Beach.
The beaches in the region that remain open and safe for swimming are Beaverton Beach North, Elgin Pond, Frenchman’s Bay East and West, Kinsmen Beach, and Thorah Centennial Park.
The health department will be conducting water tests on a weekly basis throughout the summer.