Seth’s Pond in West Tisbury has been closed until further notice due to high levels of bacteria, health agent John Powers announced Tuesday.

The freshwater pond will be re-tested Friday, Mr. Powers said; it will be reopened pending the return of clean water samples.

This is the second time the popular swimming pond off Lambert’s Cove Road has been closed this season. In June the pond was briefly closed when a water sample showed high levels of enterococcus bacteria.

According to the state Department of Public Health, enterococcus bacteria is an indicator organism that could signal the presence of harmful bacteria in the water. Swimming in water with high levels of enterococci can be dangerous for young children, the elderly and people with compromised immune systems.