North Fork Big Thompson River

North Fork Big Thompson River
Basin features
Main source	13,120 ft (4,000 m) 40°29′20″N 105°38′38″W / 40.48889°N 105.64389°W / 40.48889; -105.64389
River mouth	Confluence with Big Thompson 6,152 ft (1,875 m) 40°25′57″N 105°20′20″W / 40.43250°N 105.33889°W / 40.43250; -105.33889Coordinates: 40°25′57″N 105°20′20″W / 40.43250°N 105.33889°W / 40.43250; -105.33889
Progression	Big Thompson South Platte—Platte Missouri—Mississippi

The North Fork Big Thompson River is a 22.7-mile-long (36.5 km)tributary of the Big Thompson River in Larimer County, Colorado. The river's source is Rowe Glacier on the north slope of Hagues Peak, in the Mummy Range of Rocky Mountain National Park. It flows through Lake Dunraven, over Lost Falls and through Glen Haven before a confluence with the Big Thompson in Drake.