LEWISTON – Public works crews were seeking the source of a major leak Friday within the city’s water system.

Public Services Director David Jones described the leak as substantial, with a loss of 3,500 gallons per minute, but said there have been no reports of interruptions in water service or threats to public safety.

By late afternoon, Jones estimated that 4 million gallons had been lost.

The city became aware of the problem when it realized that the water level in a reservoir was unusually low.

Crews were working since early morning to locate the leak and planned to remain on the job during the night until it is detected. Once the leak is located, the site will be isolated and repairs made.