Clark Canyon Dam


Clark Canyon Dam is constructed at the head of the Beaverhead River. The zoned earthfill dam has a structural height of 147.5 feet, a crest length of 2,950 feet, and a volume of 1,970,000 cubic yards of material. The spillway consists of an approach channel, concrete inlet channel, ungated concrete crest, concrete chute, concrete stilling basin, and an outlet channel. The outlet works consists of an approach channel; concrete intake structure; concrete conduit; a gate chamber with high-pressure gates, two of which serve for emergency ahead of the regulating gates; concrete access shaft and shaft house; and a concrete stilling basin. The outlet channel is shared by the outlet works and spillway.

RegionFacilities in Great Plains | Great Plains Home Page
ProjectEast Bench Unit, Pick-Sloan Missouri Basin Program
Dam TypeZoned earthfill
ReservoirClark Canyon
WatercourseBeaverhead River
LocationTwenty miles southwest of Dillon, Montana at the head of Beaverhead River in southwestern Montana.
Original Construction1961-1964
Modified Construction1984: Tile toe drains were replaced and new drain field was constructed.
National ID NumberMT00569
Hydrologic Unit Code

Structural Height147.50 ft
Hydraulic Height (Normal Operating Depth at Dam)113.90 ft
Top Parapet (Elevation)
Spillway Crest Elevation5,560.40 ft
Crest Elevation5,578.00 ft
Crest Length2,950.00 ft
Crest Width36.00 ft
Base Width 800.00 ft
Volume of Dam Construction Materials 1,970,000.00 cu yds
Streambed at Dam Axis
Top of Exclusive Flood Control Pool (Elevation)
Top of Joint Use Pool (Elevation)5,546.10 ft
Top of Active Conservation Pool (Elevation)5,535.70 ft
Top of Inactive Conservation Pool (Elevation)5,470.60 ft
Top of Dead Storage Pool (Elevation)5,455.00 ft

Hydraulics & Hydrology
Total Water Storage at Elevation257,152.00 acre-ft at 5,560.40 ft
Maximum Water Surface Elevation 325,324 acre-ft at 5,571.90 ft
Normal Water Surface Elevation
Spillway TypeUncontrolled concrete crest and concrete-lined chute at left abutment
Auxiliary Spillway
Spillway Capacity at Elevation9,520.00 cfs at 5,571.90 ft
Auxiliary Spillway Capacity at Elevation
Uncontrolled Spillway Capacity at Elevation
Outlet Works Capacity at Elevation2,325.00 cfs at 5,547.00 ft
Diversion Capacity at Elevation
Drainage Area
Hydrometeorological Report (HMR)
Probable Maximum Flood (PMF) Report

Contact Information
TitleArea Manager
OrganizationMontana Area Office
AddressP.O. Box 30137
CityBillings, MT 59107-0137
Phone (Fax)406 247-7338
Phone (Office)406 247-7300
OrganizationEast Bench Irrigation District
Address1100 Highway 41
CityDillon, MT 59725
Phone (Office)406 683-2307

Last updated: Mar 29, 2013