Yellowtail Dam & Bighorn Lake Billings, Montana January 2011 RECLAMATION Managing Water in the West

Operating Requirements & Objectives Mandatory /Legal –Recognize all senior downstream water rights –Fulfill compact obligation with Native American Tribes –Meet contract commitments for stored water –Dam safety Operating Objectives –Maximize power generation benefit –Maintain storage space for flood control –Maintain desired lake levels for recreation, reservoir fishery and waterfowl –Maintain desired river flows for the river fishery and water quality

Multipurpose Benefits Water Rights –Regulate stream flow and release water for irrigation Compact Commitments with N. Cheyenne and Crow tribes Industrial water supply –6,000 AF contract with PPL- MT Flood control –Flood protection Benefits= $113 million since construction (2007) Hydropower –260 MW powerplant (8,000 cfs) –Peaking power supplied to two grid systems –Average Annual generation = million kwhrs ( ) –Average Annual power = $20 million per year –Montana and Wyoming both benefit from power generated Fish & Wildlife –Lake fishery, river fishery, and waterfowl Recreation –Bighorn Canyon Recreation Area and Bighorn River Water Quality –Reduce high levels of nitrogen supersaturation –Sediment retention

Operational Goals Prior to Review Desired lake elevations requested by lake interests –Minimum desired lake elevation recommended by the NPS for the summer recreation season –Minimum late fall lake elevation recommended by the Wyoming Game and Fish to provide suitable waterfowl habitat –Draft reservoir to 3630 to prevent ice-jams from forming in low end of Shoshone River –Maximum lake elevation recommended by the NPS for the summer recreation season to protect facilities –A rising reservoir level through the spring for walleye spawning.

Operational Goals (continued) Desired river flows requested by Montana FW&P by letter dated November 19, ,500 cfs – to provide good spawning, rearing and cover conditions in all major side channels. 2,000 cfs - to provide adequate spawning and rearing conditions in most side channels but cover for adult fish is limited. 1,500 cfs – to provide only main channel habitat and no side channel habitat Minimum release included in the 1962 Definite Planning Report for the Yellowtail Unit – 1,000 cfs

Operational Goals (continued) Power generation –Utilize available water supply to maximize generation at time of greatest demand –Maximize reservoir head to provide the greatest generation per unit of water Flood control –Coordinate operations with the Corps of Engineers to provide system benefits –Draft water from the Joint-Use pool based on mountain snowpack forecast to provide space for expected runoff while allowing the reservoir to fill to the top of the joint-use pool by end of July. –Operate the Exclusive flood pool as directed by the Corps of Engineers to control rain flood events and high snowmelt runoff.

QUESTIONS & COMMENTS