2 Closed Marblehead Beaches To Be Re-Tested For Bacteria Tuesday

MARBLEHEAD, MA — Two Marblehead beaches will be closed through the Fourth of July after bacteria tests came back at unacceptably high levels.

Marblehead Director of Health Andrew Petty said Grace Oliver's Beach and Gas House Beach will be closed to swimming until at least Tuesday after exceeding the limit for Enterococci bacteria.

According to the Centers for Disease Control and Prevention: "Enterococci are a type of bacteria mainly found in the gut and feces of animals. They are used as an indicator organism for groundwater because they closely link water quality with contamination by human feces. Some enterococci can cause disease in humans."

The average of Enterocci colonies exceeded the maximum of 35 per 100 milliliters at both beaches. The mean was 53.6 at Gas House Beach and 51.7 at Grace Oliver's Beach over the past five weeks.

Petty said because of Friday's rain, the beaches will not be retested until Tuesday.

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(Scott Souza is a Patch field editor covering Beverly, Danvers, Marblehead, Peabody, Salem and Swampscott. He can be reached at Scott.Souza@Patch.com. Twitter: @Scott_Souza.)