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Bitter Root Project
Bitter Root Project | Project History | Project Data | Contact Information

Project Data
Land Areas (1992)
Area Irrigated and Crop Value



Project # 226


Land Areas (1992)
Irrigable area:
Full Irrigation Service16,379 acres
Supplemental Service0 acres
Temporary Irrigation Service0 acres
Number of Irrigated Farms793
Residential, Commercial, Industrial Lands286 acres
Total Irrigable Lands16,665 acres


Population Served:

Farm Population Served2,807
Non-Farm Population Served715
Total Population Served3,522


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Area Irrigated and Crop Value
YearActual Area Irrigated (Acres)Crop Value (Dollars)


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Project Water Supply
Project Water Quality




Project Water Supply

Current Conditions

Reservoir Storage

Como Lake near Hamilton, Montana

Weather Conditions (NOAA)


Bitterroot River near Darby, Montana (USGS)

Streamflow Forecast Map

Spring and Summer (NRCS)
Snowpack Information

Columbia River Snowpack Summary
Mountain Snowpack Maps for Columbia River Basin
Drought Index

Palmer Drought Index Map
Explanation of Palmer Drought Severity Index (Text)


Historic Conditions

Annual Precipitation
Normal13.27 in
Maximum - 198020.11
Minimum - 19668.90 in
Hamilton, Montana 1961-1990 


Mean Annual46 ?F
Daily Maximum - 07/23/1895105 ?F
Daily Minimum - 02/04/1899-39 ?F
Hamilton, Montana 1895-1996 
Growing Season148 days
Elevation of irrigable area3,500 ft


Rock Creek
Drainage area above Lake Como55 mi2
Annual discharge: 
Maximum - 1959122,259 acre-ft
Minimum - 195384,423 acre-ft
Average - 1946-1959106,687 acre-ft

Streamflows: Rock Creek near Darby, Montana (USGS)


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Project Water Quality


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Facilities in Operation
Storage Facilities
Diversion Facilities
Carriage Facilities



Facilities in Operation
Storage Dams1
Diversion Dams1
Canals67 mi
Laterals77 mi


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Storage Facilities

Como Dam

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Diversion Facilities
Rock Creek Diversion
Type:Timber sheet piling, concrete weir cap, rockfill
LocationOn Rock Creek, about 15 miles south of Hamilton, Montana.
Year Completed1950
Dimensions:10.5 ft
Structural height4.5 ft
Hydraulic height4.5 ft
Crest length80 ft
Crest elevation (assumed)4,060.0 ft
Volume600 yd3
Headworks:Concrete, three 48-in-square steel slide gates.
Diversion Capacity330 cfs

Grid Notes

1 Dam replaced timber-crib weir constructed in 1910


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Carriage Facilities
Bitter Root Irrigation District Canal
LocationFrom Rock Creek Diversion Dam on Rock Creek about 15 miles south of Hamilton, Montana, generally north along east side of Bitterroot River to a point about 5 miles northeast of Florence, Montana
Construction Period1907-1910
Length72 mi
Diversion Capacity330 cfs
Typical section in earth: 
Bottom width22 ft
Side Slopes1.5:1
Water depth5.25 ft


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Last updated: Dec 09, 2009