An obscure commission in Harrisburg will vote Thursday on important new rules to protect the state's drinking water from the effect of expanded natural-gas drilling.

The five men who serve on the state Independent Regulatory Review Commission ordinarily don't get much attention. But the panel reviews proposed state regulations to ensure they are in the public interest.

That's clearly the case with new rules proposed by the state Department of Environmental Protection and the Environmental Quality Board. The aim is to ensure that the state's streams and rivers don't get polluted in the rush to drill for natural gas in the lucrative Marcellus Shale fields.

During a process known as "fracking," drillers pump millions of gallons of water, sand, and chemicals underground to break apart the shale deposits and release the gas trapped in the rock. Much of that fracking fluid comes back to the surface, in concentrations saltier than ocean water.

The level of total dissolved solids in the wastewater is harmful to aquatic life, enabling algae blooms that can wipe out fish and other species. Although it was not linked specifically to a drilling operation, high levels of dissolved solids in September 2009 polluted 26 miles of Dunkard Creek in Greene County, killing at least 18 species of fish.

Other sources of these solids include drainage from abandoned mines, storm-water runoff from farms, and discharges from industrial or sewage-treatment plants.

At the urging of environmental groups and some drilling companies, the DEP has been working for nearly two years to devise new regulations for handling the wastewater. The result is a proposed rule that requires companies to treat the wastewater to the same quality as drinking water before it can be discharged into streams.

A second measure would set up buffer zones of at least 150 feet in width to separate new developments from high-quality streams.

DEP has held public hearings on these proposals and received more than 4,000 comments from the public.

The legislature also must review these proposed regulations before they can take effect. The regulatory review commission should approve them to take an important step toward protecting the state's waterways before the drilling begins in earnest.