Canyon Ferry Dam


Canyon Ferry Dam and Powerplant are on the Missouri River about 1.5 miles downstream from the original Canyon Ferry Dam and the Montana Power Company's 6,700 kilowatt in the backwater Hauser Lake. The dam is a concrete gravity structure approximately 1,000 feet in length along the crest with a structural height of 225 feet. It contains 414,400 cubic yards of concrete. The spillway is an overflow section in the central portion of the dam, controlled by four radial gates. The spillway capacity is 150,000 cfs. The total capacity is 2,051,000 acre-feet at elevation 3,800.00. Four river outlets are in the spillway section of the dam. The maximum discharge capacity of these outlets is 9,500 cfs. One 156-inch-diameter pumping intake pipe is embedded in the concrete of the dam near the left abutment for the Helena Valley Pumping Plant. Three 162-inch-diameter penstock pipes for the power generating units are embedded in the dam near the right abutment. The powerplant is on the right downstream toe of the dam adjacent to the spillway apron. It is of reinforced concrete construction and houses three 16,667-kilowatt vertical-shaft generators driven by 23,500-horsepower turbines.

Foundation Geology:

Massive, fine-grained, hard and dense hornfels (transformed empire shale) fractured into an exceedingly complex and closely spaced system of joints, with several minor and one major fault zone and a major bedding plane slip. Special treatment: Grout blanket over foundation area and grout curtain under dam.

RegionFacilities in Great Plains | Great Plains Home Page
CountyLewis and Clark
ProjectCanyon Ferry Unit, Pick-Sloan Missouri Basin Program
Dam TypeConcrete Gravity
ReservoirCanyon Ferry Lake
WatercourseMissouri River
LocationOn the Missouri River 27 miles downstream from Townsend Montana.
Net Generation277,052,777 kWh
Original Construction1949-1954
Modified Construction
National ID NumberMT00568
Hydrologic Unit Code

Structural Height225.00 ft
Hydraulic Height (Normal Operating Depth at Dam)172.00 ft
Top Parapet (Elevation)3,810.69 ft
Spillway Crest Elevation3,766.00 ft
Crest Elevation3,808.50 ft
Crest Length1,000.00 ft
Crest Width20.00 ft
Base Width173.00 ft
Volume of Dam Construction Materials414,400.00 cu yd
Streambed at Dam Axis
Top of Exclusive Flood Control Pool (Elevation)
Top of Joint Use Pool (Elevation)3,797.00 ft
Top of Active Conservation Pool (Elevation)3,770.00 ft
Top of Inactive Conservation Pool (Elevation)3,728.00 ft
Top of Dead Storage Pool (Elevation)3,650.00 ft

Hydraulics & Hydrology
Total Water Storage at Elevation1,891,888 acre-ft at 3,797.00 ft
Maximum Water Surface Elevation 1,992,977acre-ft at 3,800.00 ft
Normal Water Surface Elevation
Spillway TypeOverflow section at center of dam, controlled by four 51- by 34.5 ft radial gates.
Auxiliary Spillway
Spillway Capacity at Elevation150,000.00 cfs at 3,800.00 ft
Auxiliary Spillway Capacity at Elevation
Uncontrolled Spillway Capacity at Elevation
Outlet Works Capacity at Elevation9,500.00 cfs at 3,800.00 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
TitleArea Manager
OrganizationMontana Area Office
AddressP.O. Box 30137
CityBillings, MT 59107-0137
Phone (Fax)406 247-7338
Phone (Office)406 247-7300

Last updated: Mar 29, 2013