Hydraulic fracturing produces vast quantities of salty water called brine. Until recently, a lot of this brine ended up in rivers and streams, where it eventually posed a danger to drinking water. Pennsylvania thought it solved this problem by keeping this waste out of treatment plants. But as The Allegheny Front's Reid Frazier and Ann Murray found, the problem hasn't gone away. Scientists are scrambling to find out why, and what to do about it.