| North Fork Big Thompson River[1] | |
| Pushpin Map: | Colorado |
| Pushpin Map Caption: | Location of mouth |
| Source1 Coordinates: | 40.4889°N -105.6439°W |
| Mouth Coordinates: | 40.4325°N -105.3389°W |
| Source1 Elevation: | 13120feet |
| Mouth Elevation: | 6152feet |
The North Fork Big Thompson River is a 22.7adj=midNaNadj=mid[2] 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.