Clark Canyon Hydro LLC on Nov. 20 filed a final license application with the Federal Energy Regulatory Commission for a hydroelectric project to be added at the existing Clark Canyon Dam in Montana.
The Flood Control Acts of 1944 and 1946 approved the construction of the Clark Canyon Dam as part of the Bureau of Reclamation’s (BOR) Pick‐Sloan Missouri River Basin Program, East Bench Unit. The approximate 2,950 foot (ft) zoned, earth‐fill dam includes a concrete intake structure and conduit in the reservoir, shaft house at the crest of the dam, a 9‐ft‐diameter conduit that discharges water to a concrete stilling basin, a gate chamber with four high pressure gates, two of which act as emergency gates, and an uncontrolled concrete spillway.
Located near the town of Dillon in Beaverhead County, Montana, the Clark Canyon Dam is situated on the Beaverhead River. Uses for the water at the dam for authorized project purposes include irrigation, flood control, fish and wildlife, and municipal water. No proposed new dams or reservoirs are included in the Clark Canyon Dam Hydroelectric Project.
The dimensions of the powerhouse to be built will be approximately 46 feet by 65 feet. The powerhouse will contain two vertical Francis-type turbine/generator units with a combined generating capacity of 4.7 MW, and a combined discharge capacity of 700 cubic feet per second (cfs).
The powerhouse substation will be located northeast of the powerhouse (approximately 1,100 ft downstream of the powerhouse). The substation includes a 4.16 kV to 69 kV step-up transformer with switchgear on concrete pad foundations with containment and a grounding grid. An underground transmission line will be between the powerhouse and the powerhouse substation.
The new transmission line will run from the powerhouse substation approximately 7.9 miles to the Peterson Flat substation and will be adjacent to and within sections of the Highway 324 right-of-way (ROW).
At the selected size, the project will use flows ranging from 87.5 cfs to 700 cfs (87.5 cfs to 350 cfs per unit), and will have a maximum static head of 110 feet and an average static head of 87 feet. On average, the project will generate approximately 15.4 gigawatthours (GWh) per year. The project will function in a “run-of-river” mode with no daily storage for power generation, and no peaking operation.