Sep. 6--A battle is brewing over proposed rules designed to protect the state's water resources from high levels of pollutants -- action prompted by a boom in natural gas drilling that generates millions of gallons of wastewater laced with salts and chemicals.

Demand for treating wastewater from oil and gas production in the state is expected to reach about nine million gallons a day this year, according to a state Department of Environmental Protection report. It is projected to increase to 16 million gallons next year and 19 million gallons a day in 2011, when new standards limiting such pollution would take effect.

By comparison, the current level is only about 5 percent of the 200 million gallons of residential and industrial wastewater generated daily in Pittsburgh and 82 other communities in Allegheny County and treated by Alcosan, which does not accept the oil and gas well wastewater. Eleven of 13 other treatment plants in Western Pennsylvania are under state orders to limit the amount of drilling wastewater they treat, most at levels no more than 1 percent of daily flow.

The wastewater mainly comes from a drilling process called "fracking" -- in which hydraulic fluid mixed with sand and chemical additives is pumped underground at high pressure to crack rock formations holding natural gas and oil reserves. The process creates water containing dissolved solids, toxic metals and organic pollutants. Brine water, trapped underground in the rock formations, flows back to the surface as well.

Demand for treatment capacity comes at a time when drilling activity remains robust, despite the recession. It is driven by surging activity in the Marcellus Shale region in Pennsylvania and portions of surrounding states, which is estimated to hold enough natural gas to meet the country's needs for more than a decade.

Through mid-August, the DEP issued 1,067 permits for gas drilling statewide, compared with 476 for all of last year. The number of Marcellus wells drilled totaled 283, up 45 percent from 2008's 195 total.

Because of so much drilling, "these guidelines are really needed," said Thomas Hoffman, Western Pennsylvania director for Clean Water Action in Pittsburgh.

From the oil and gas industry's perspective, the proposed standards "are extremely stringent," much more so than other states where natural gas is produced, said Stephen Rhoads, president of the Pennsylvania Oil and Gas Association, a Harrisburg trade group.

"We have to see whether or not it is even feasible to comply," Rhoads said.