Gunbarrel is an unincorporated community and a census-designated place (CDP) located in and governed by Boulder County, Colorado, United States. The CDP is a allocation of the Boulder, CO Metropolitan Statistical Area. The population of the Gunbarrel CDP was 9,263 at the United States Census 2010. The Boulder publish office (Zip Code 80301) and Longmont and Niwot declare offices (Zip Code 80503) serve the area.

Gunbarrel is northeast of the city of Boulder proper, separated by a buffer area of private agricultural lands and publicly owned door space. The buffer areas provide exceeding two miles (3 km) of separation over changing elevations. This reduces the impact of the Boulder Municipal Airport and the Boulder County Sheriff’s Department facilities (including the county jail), which are located on the southern side of the buffer.

Two reservoirs operated by the Boulder and Left Hand Irrigation Company are located in central Gunbarrel. Irrigation ditches and canals, including the Boulder and Whiterock Ditch, pass through this primarily residential area. The Twin Lakes Open Space, a large park which includes the two reservoirs and extends west along the ditch, is operated by the Boulder County Parks and Open Space Department. The park brings protected wetlands, jogging trails and green spaces directly into the urban area. The City of Boulder operates Eaton Park, adjacent to the west lake. Eaton Park includes picnic facilities, BMX jumps and additional protected wetland. Flood direct facilities are integral to the reservoir and canal systems, but they reach not eliminate the flood risk to neighboring development.

The Gunbarrel CDP has an Place of 4,038 acres (16.340 km), including 38 acres (0.155 km²) of water.