Colchester, including the hamlets of Downsville, Cooks Falls, Horton, Shinhopple, and Corbett, is located in the southern part of the county and borders Sullivan County. According to the United States Census Bureau, the town has a total area of 142.2 square miles and a 2010 Census of 2,042 people.
Colchester was one of the seven constituent towns when Delaware County was formed in 1795. Joseph Gee, an early settler in Colchester was successful in having the town named after his home town of Colchester, Connecticut. Prior to that, the original area of Colchester was known by Lenni-Lenape name of Pawpacton.
The town of Colchester is dominated by three mountains in the center of the township; Baxter Mountain, Campbell Mountain and Brock Mountain. To the west, Bear Spring Mountain forms the barrier between Colchester and Walton and Houck Mountain in the southwest divides Colchester from Hancock.
Two main rivers run through the township. The East Branch of the Delaware River (taken from the Lenape name Papagonk meaning East Branch Delaware) and on eastern border by the Beaverkill River. The Beaverkill was referred to as the Whelenaughwemack by the original Lenni-Lenape people, which depended on this and the East Branch river flats for their agriculture, hunting and fishing grounds. Several brooks flow into these rivers. In Cooks Falls Horton area are Russell Brook, Cook Brook and Horton Brook enter the Beaverkill and further upstream, Berry Brook and Spring Brook also flow to the Beaverkill.
Downs Brook feeds into the East Branch at Downsville, part of that brook comes from the Tub Mills Falls and parts coming from Wilson Hollow, Telford and Gregory Hollows. Trout Brook at Shinhopple and Campbell Brook at Corbett also feed the East Branch.