After a business overlay passed in Murrysville near its border with Export, public officials there anticipated that a new large-scale commercial development would bring more business to the community.

But in lower-lying Export, residents and public officials fear it could bring something else: flooding.

Residents and borough council members partly blame development in Murrysville for the increase in flooding because of poor storm water management. Residents say flooding has gotten worse in recent years as development in Murrysville has boomed.

Export council registered opposition to the overlay, which passed at a Murrysville council meeting in early August, in two official letters sent in December then in May.

At its Aug. 19 meeting, council voted unanimously to send a third letter.

Murrysville Mayor Joyce Somers said she has tried to reassure Export council members who met with Murrysville officials that a development will not mean more storm water. She pointed to a Murrysville ordinance that requires developers to prove their development will generate less storm water than the land does currently.

"Murrysville has the best storm water runoff ordinances in the entire county," she said. "We're not only concerned about flooding Export, we're concerned about flooding our own community."

The problem with the ordinance is it is difficult to calculate how much storm water a property generates, said Diane Selvaggio, a biologist with the Turtle Creek Watershed.

"The reality of the situation is you don't have good baseline data for the pre-development conditions," she said. "As near as I can tell, there's no municipality in the state that has good baseline data ... for what these pre-development conditions truly are."

Councilwoman Melanie Litz also worries the development may hurt Export's efforts to draw new business.

"We're really trying to focus on revitalizing our downtown business district ... and that's going to be hard to do with big box stores and chain stores."

Councilman George Wood said Export's consumers are loyal to the town's handful of businesses "and there's nothing they're going to put in there that's going to hurt Export."

Jim Kress, an Export resident who is on the Turtle Creek Watershed board of directors, said commercial development may bring jobs to the area. His primary concern is preventing more pollution in the creek, which already has mine acid.

A retired developer who oversaw a 71-acre development in Salem, he said developers typically employ storm water diversion techniques that overwhelm creeks and rivers rather than managing the storm water on-site because it's too expensive. Turtle Creek, he said, cannot handle any more storm water.

Export Solicitor Wesley Long has told council it can file an injunction to prevent further work on the property when developers go to Murrysville council for approval of their plan.

Mayor Somers said Export's opposition to development is premature, given that there is not yet a plan.