That’s the share of streams in Pennsylvania’s Allegheny County that are classified as “impaired,” meaning their waters do not meet state standards for drinking, fishing or swimming. The designation applies to 915 miles of waterways, a far higher rate than the 37 percent statewide average, according to a draft report from the Pennsylvania Department of Environmental Protection. Officials say centuries of mining, industrial activity and urban runoff have left a legacy of pollution that remains costly and slow to fix.
