Deer Creek is a 52.9-mile-long (85.1 km)[1] river in Maryland and Pennsylvania that flows through the scenic areas of Harford County and empties into the Susquehanna River, roughly halfway between the Interstate 95 bridge and Conowingo Dam. Its watershed area is 171 square miles (440 km2).[2] Its watershed area in MD (excluding water) is 145 square miles (380 km2), with 3% impervious surface in 1994.[3] It serves as a divider between the agricultural and urban/suburban areas of Harford County.