Chilmark town officials have posted a closure for Squibnocket Beach due to an unacceptably high average bacterial count.

The closure sign, which says bathers may choose to swim at their own risk, was required by the state Department of Public Health regulations.

The sign explains to swimmers:

“These regulations state that the average of the last five bacterial water samples must be below a certain level. Our average is still slightly above the required limit.

“On July 5, 2011, we experienced an anomalous reading of 2,420. All tests since that date have been at or below safe limits, with the exception of a test on July 11, which was 10 points above the limit of 104 set by the Department of Public Health.

“Our last test, on July 18, 2011, measured 27, well below the safe level of 104.

You may choose to swim at your own risk.”

The town is awaiting test results samples taken this morning.