The Weskeag River is a short tidal river in Knox County, Maine. The Abenaki Indians called it Wessaweskeag, meaning "tidal creek" or "salt creek". From its source (44°04′13″N69°09′38″W) in South Thomaston, the river runs 1.2 miles (1.9 km) northeast and southeast to its confluence with Marsh Creek, then 4.2 miles (6.8 km) southeast through its estuary to the Muscle Ridge Channel of West Penobscot Bay.