Dry-Redwater Regional Water Authority System Act of 2011 - Authorizes the Secretary of the Interior to carry out the project entitled the "Dry-Redwater Regional Water Authority System" in accordance with the plans described in the "Dry-Redwater Regional Water System Feasibility Study" if the Secretary determines that the project is feasible.
Directs the Secretary to enter into a cooperative agreement to provide federal assistance for the planning, design, and construction of the Dry-Redwater Regional Water Authority for specified counties in Montana and North Dakota.
Limits the federal share of planning, design, and construction of the System to 75% of the total cost. Delineates the components of System facilities for which federal funds may be expended. Prohibits federal funds from being used for the System's operation, maintenance, or replacement.
Directs the Administrator of the Western Area Power Administration to make available to the System a quantity of power required, up to one and a half megawatt capacity, to meet the System's pumping and incidental operation requirements between May 1 and October 31 of each year from the water intake facilities and through all pumping stations, water treatment facilities, reservoirs, storage tanks, and pipelines up to the point of delivery of water by the water supply system to all storage reservoirs and tanks and each entity that distributes water at retail to individual users. Makes the System eligible to receive such power only if it operates on a nonprofit basis and is constructed pursuant to the cooperative agreement. Sets forth provisions regarding the purchase of additional power, the Authority's responsibility for power charges and non-federal delivery costs, and the System's responsibility for non-federal transmission and distribution system delivery and service arrangements and for funding any transmission upgrades required to the integrated system necessary to deliver power to the System.