From The Washington Post: Maryland's new rules limiting sand, dirt and other gunk in Montgomery County waterways have caught an improbable violator in its net: the public school system and its 199 campuses. The system's acres of blacktops, parking lots and ballfields carry stream-clogging runoff into nearby creeks every time it rains, contributing to downstream pollution. But finding a way to fix the problem might force officials to make difficult choices in tough economic times. Amid government furloughs and job cuts, the school system will have to find a way to pay for drainage improvements.