The Saint George River is a river in Maine with a watershed of 225 square miles (580 km²) in a unique and historic area of mountains, sea coast, lakes, tidal streams and inlets. The origin of the Saint George River is the outflow of Saint George Lake (44°23′42″N69°18′41″W) in Liberty. The river follows a winding course 45 miles (72 km) south to Thomaston, where the river flows into the estuary and runs about 12 miles (19 km) miles southwest to Muscongus Bay, forming the border between Cushing and St.