So if some energy companies want to punch natural-gas wells deep into a shale formation in the Southern Tier, why does it matter in Monroe County? Think water.

Environmental watchdogs say that's one potential issue with drilling in the Marcellus Shale, a massive natural-gas-rich rock formation that spans several states and ends around Monroe County's southern border. The drilling operations will use a technique called hydraulic fracturing - fracking, for short - which requires immense quantities of water; each gas well is expected to use more than one million gallons. To meet those needs, drilling companies would draw water from local rivers and lakes - including Ontario and Erie. They might also draw water from local aquifers, which could lead to depletion.

"Right now it's a patchwork of regulations that guide water withdrawals," says Katherine Nadeau, water and natural resources program associate for Environmental Advocates of New York. Some areas, like the Susquehanna and Delaware River basins, have detailed restrictions. The two Great Lakes are not regulated yet, though they will be once New York takes the technical steps to enact an international agreement that restricts large withdrawals.

With the drilling operations comes the potential for spills; fracking fluid contains chemicals to help break open the rock. Draft regulations for Marcellus and Utica shale drilling released recently by the DEC require drillers to disclose the composition of fracking fluid. They also impose some restrictions on storing and transporting fracking fluid.

"It's a huge document," says Sarah Eckel, a spokeswoman for Citizens Campaign for the Environment. For that reason, environmental groups are asking the state to extend the comment period, which ends November 30.

To help inform area residents on the issues surrounding gas drilling in the Marcellus Shale, local environmental groups, as well as the League of Women Voters, are hosting a forum at 7 p.m. on Monday, October 19, at Brighton Town Hall, 2300 Elmwood Avenue. The event will feature a panel of experts, including a primer by Wes Gillingham, the director of Catskill Mountain Keeper.