Sam Rayburn Reservoir is a reservoir in the United States located in Deep East Texas, 70 mi (110 km) north of Beaumont. The reservoir is fed by the Angelina River, the major tributary of the Neches River. The capacity of the reservoir is 3,997,600 acre feet (4.9310×109 m3), and is the largest lake wholly located within the state of Texas. The reservoir is operated by the United States Army Corps of Engineers, Fort Worth district.