A bill to authorize the Secretary of the Interior to construct, operate, and maintain modifications of the existing Buffalo Bill Dam and Reservoir, Shoshone project, Pick-Sloan Missouri Basin program, Wyoming, and for other purposes.

Authorizes the enlargement of the Buffalo Bill Dam and Reservoir, Wyoming, for various purposes, including water supply, recreation, and fish and wildlife conservation. Requires repayment contracts for the costs of municipal and industrial water supply be negotiated prior to construction of such facilities. Sets forth the formula for computing interest during the construction of the modifications.