Among the uses banned by the restrictions are car washing and watering grass and flowers, he said.
Mercersburg's drinking water comes from Buck Run, a mountain stream that flows into an 11-million-gallon reservoir behind the James Buchanan Birthplace State Park west of town.
"At this point the reservoir is down to about 7.4 million gallons," Sherrow said. "I've never seen it this low."
Water from the reservoir runs back into Buck Run below the spillway. Several tributaries that flow into Buck Run above the reservoir have run dry, Sherrow said.
The supply is augmented by a mountain well that feeds into the treatment plant downstream from the reservoir. A second well could also be pressed into service if needed, although it tests high in nitrates, Sherrow said. He said the second well is a cushion.
"We're not going to run out of water," he said.
The state, under its conservation rules, makes the borough release 218,000 gallons of water back into Buck Run below the dam every day. The reason is to maintain proper flow in the stream to protect its wildlife. Sherrow thinks that's too much considering current conditions.
He's asking the state to reduce the outflow requirement to 25,000 gallons per day, and is optimistic the state will grant the request.
"That will be enough to keep the stream level up and allow me to keep a couple of months of storage capacity in the reservoir," Sherrow said.