East Lyme — Town officials are implementing mandatory water conservation measures for all town utility customers effective 9 a.m. today in the aftermath of a recently discovered diesel fuel leak at Niantic’s York Correctional Institution, according to a Department of Correction news release.

The department has said a broken underground pipe led to a diesel fuel leak that was contained on the grounds of the prison. The leak was discovered about three weeks ago in the area that supplies about half of the town’s water supply for the 6,500 town utility customers, said East Lyme First Selectman Paul Formica.

Formica said the conservation measures will help to slow water flow and aid ongoing testing at the on-site monitoring wells.

Kropp Environmental, a state-licensed contractor, is managing the remediation plan and continues to test the soil and 40 monitoring wells for contamination each day. Kropp representatives will continue to monitor the situation through and after the holiday weekend.

The Department of Correction said in the release that no contaminated soil has been found outside the correctional facility’s grounds and the exact amount of fuel spillage has not been discovered.

The following restrictions will apply to all customers of the East Lyme Water System: Prohibiting the sprinkling, watering or irrigation of lawns; prohibiting washing of motor vehicles and the outdoor surfaces of all buildings and structures, sidewalks and driveway; prohibiting the filling or cleaning of swimming and wading pools; and prohibiting the service of water to customers of public restaurants except at the specific request of customers.

The measures will remain in place through Monday.