East Lyme — The Ledge Light Health District has closed several local beaches after about 15,000 to 20,000 gallons of sewage spilled Wednesday into a storm drain in the vicinity of the Niantic River bridge.

The following beaches are closed: McCook’s Point, Hole in the Wall, Pine Grove, Oswegatchie and Crescent.

First Selectman Paul M. Formica said the spill occurred around 2 p.m. Wednesday at a pump station on Route 156.

He said effluent spilled through manhole covers and possibly into catch basins after a computer at the station failed to turn on a pump when the waste in the well reached a certain level.

He said spare parts for the computer were on hand, and a vendor fixed the computer. In the meantime, the pump was operated manually.

Formica said he believes that less sewage was spilled than was reported. He doesn’t believe that the incident will affect any of the activities scheduled for Saturday’s Celebrate East Lyme festivities.

Stephen Mansfield, deputy director of health at the health district, said samples of the water were taken Thursday morning and will be taken to the state Department of Public Health.

Mansfield said it takes 24 hours for bacteria to grow, and he will know by Friday afternoon whether the beaches can reopen.

Swimming or wading in these waters is restricted until further notice.

i.larraneta@theday.com