To authorize the Secretary of the Interior to construct facilities to provide water for irrigation, municipal, domestic, military, and other uses from the Santa Margarita River, California, and for other purposes.

Authorizes the Secretary of the Interior (the Secretary) to construct, operate, and maintain the Santa Margarita River Project in accordance with the final feasibility report and this Act.

Authorizes Project construction only after the Secretary determines that: (1) the Fallbrook Public Utility District, San Diego County, and the Navy have entered into contracts to repay to the United States appropriate construction, operating, and maintenance costs (permits the Secretary to allow satisfaction of the repayment obligation of construction costs through payment of the Navy Secretary's share prior to initiation of construction); (2) the authorized California officer or agency has granted water use permits to the Bureau of Reclamation; (3) the District has agreed that it will not assert against the United States any prior right to water in excess of the quantity deliverable under this Act and will share water based on equal priority and a specified ratio; and (4) the Secretary has determined that the Project has completed applicable economic, environmental, and engineering feasibility studies.

Makes the Navy Secretary responsible to pay only that portion of costs that reflects the extent to which the Navy Department benefits from the Project.

Permits operation of the Project by the Secretary, the District, or a third party, subject to a memorandum of agreement and under regulations satisfactory to the Navy Secretary regarding the Navy Department's share of the Project.

Requires the Secretary and the District to participate in the Project yield on the basis of equal priority, with 60% of the Project's yield allotted to the Navy Secretary and 40% allotted to the District. Sets forth provisions governing contracts for the sale and delivery of excess water.

Requires the District's general repayment obligation to be determined by the Secretary consistent with the Reclamation Project Act of 1939.

Authorizes the Secretary to transfer operation of the Project to the District or a mutually agreed upon third party.