LYNN, Mass. (WHDH) -- Beaches across the Bay State have reopened after they were closed due to increased bacteria in the water.

According to the Globe, beaches in Quincy, New Bedford, Eastham, Wellfleet and Nantucket were closed Thursday due to the elevated levels of bacteria.

Nantucket had 10 beach closures.

Some of the beaches were allowed to reopen Thursday evening.

The exact cause of the increase in bacteria is not known but officials believe heavy rain may have been a factor.

Affected beaches will reopen to swimmers once the levels in the water are back to appropriate levels. State officials test all of the beaches that are open to public swimming once a week for bacteria levels.