By MICHAEL RUBINKAMEach day, 300 million gallons of polluted mine water enters Pennsylvania streams and rivers, turning many of them into dead zones unable to support aquatic life. At the same time, drilling companies use up to 5 million gallons of fresh water for every natural-gas well they frack. State environmental officials and coal region lawmakers are hoping that the state's newest extractive industry can help clean up a giant mess left by the last one. They are encouraging drillers to use tainted coal mine water to hydraulically fracture gas wells in the Marcellus Shale formation, with the twin goals of diverting pollution from streams and rivers that now run orange with mine drainage and reducing the drillers' reliance on fresh sources of water. Drainage from abandoned mines is one of the state's worst environmental headaches, impairing 5,500 miles of waterways. "It's a problem (the drillers) didn't create, but hopefully a problem they can help solve," said Sen. Richard Kasunic, a southwestern Pennsylvania Democrat who's co-sponsoring legislation to spur the use of mine water in fracking. While not all mine water is chemically suitable for fracking â¿¿ and a mine discharge has to be close enough to a well pad to make transport via truck or pipeline economical â¿¿ experts believe Pennsylvania has more than enough polluted mine water to meet the needs of the drilling industry. More than 10 drillers have already received Department of Environmental Protection permission to use mine discharges for fracking, a technique in which millions of gallons of water, along with chemical additives and sand, are pumped down a well to break apart gas-bearing shale deposits. "There's a lot of potential here," said Doug Kepler, vice president of environmental engineering at Seneca Resources Corp. "People are looking for the right place to do it, the right commitment to do it, and it has to make sense for your operation."