LEAD, S.D. (AP) — The water system in Lead is losing about 4 million gallons each month, and city officials can't figure out where the water is going.

Century-old water lines are still in use throughout the town. Officials replaced all of the old lines under Main Street this summer, but it did nothing to remedy the problem.

City Utilities Supervisor Roger Thomas last week enlisted the help of an expert with the South Dakota Association of Rural Water Systems to hunt for the source of the leaks. The Black Hills Pioneer reports that Thomas and Morris Elcock found several leaks, but they don't add up to the amount being lost.

City officials are working this week to repair the leaks that were found.

Copyright 2014 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.