Pennsylvania law has not clearly set out by when a downhill landowner must sue an upland developer for storm water flooding under either tort or statutory theories. Last week, the Commonwealth Court decided Lake v. The Hankin Group, No. 278 C.D. 2013 (Pa. Commw. Ct. 2013), which offers some guidance. In Lake, the downhill landowner, the Lakes, sued the upland developer under the Clean Streams Law, the Storm Water Management Act, and the federal Clean Water Act for damage caused to the Lakes’ property by increased storm water flow during storm events from the newly developed upland property. At the trial level, the defendants were granted summary judgment based on the fact that they no longer possessed or controlled the upland property and thus no cause of action could exist under the Clean Streams Law. The Lakes’ remaining claims were determined to be time-barred.