GRANT CREEK WATERSHED

THE WATERSHED

  • Grant Creek is 18.3 miles long and flows from the Rattlesnake Wilderness down through the western outskirts of Missoula to join the Clark Fork River at GPS coordinates: 46.87, -114.10.

  • MT DEQ gives the area of the Grant Creek Watershed as 19,719 acres (30.8 sq.mi.); USFS gives the area as 18,738 acres (29.3 sq.mi).

  • The headwaters of Grant Creek reach an elevation of nearly 9,000 feet, while the elevation at its confluence with the Clark Fork River is about 3,200 feet.

  • Annual average precipitation at the closest weather station, Missoula airport, is 13.61”.

Grant Creek is identified as a "Waterbody of Concern" by MT DEQ, FWP, Trout Unlimited and Missoula City/County.

  • The segment identified as impaired by MT DEQ stretches 14.54 miles from the boundary of the Rattlesnake Wilderness to the mouth.

  • Both pollutant and non-pollutant impairments are present in Grant Creek. Pollutant causes listed by MT DEQ are nitrate/nitrite, total nitrogen, sediment and temperature.  Non-pollutant causes include alteration in streamside or littoral vegetative covers, i.e. riparian vegetation removal, flow regime modification, and excess algae (linked to nutrient pollution). 

  • MT FWP and USFS identified these additional problems: fish passage barriers, water withdrawal, stream and riparian encroachment by roads and poor in-stream pool habitat.

 

Sources:

Friends of Grant Creek