To amend the Reclamation Safety of Dams Act of 1978 to authorize improvements for the security of dams and other facilities, and for other purposes.

Amends the Reclamation Safety of Dams Act of 1978 to authorize the Secretary of the Interior to make modifications that are reasonably required to preserve the site security of Bureau of Reclamation dams and related facilities. Provides for specified reimbursement for costs incurred for building and site security activities.

Requires dam safety and site security costs allocated to irrigation, municipal, and industrial water service for the Central Valley Project, California, to be collected by the Secretary exclusively through inclusion of such costs in operation and maintenance rates, capital water rates, or both, not segregated from other project costs for separate allocation or repayment. Directs the Secretary, during site security-related construction, to consider cost containment measures.

Prohibits the obligation of funds exceeding a specified amount for carrying out actual construction to modify an existing dam, the cause of which results from new hydrologic or seismic data or changes in the state-of-the-art criteria deemed necessary for site security or structural safety purposes, prior to 30 calendar days after the Secretary has transmitted a report on such existing dam to Congress.

Requires the Secretary to: (1) report annually to Congress on building and site measures undertaken (including a summary of expenditures and information relating to a five-year plan for security measures detailed to show pre- and post-September 11, 2001 costs); (2) provide written notice to project beneficiaries upon identifying a Bureau facility for a site security measure; and (3) include in required reports the Secretary's response when a modification is the result of new data deemed necessary for structural safety purposes. Authorizes the Secretary to waive reporting requirements that could adversely impact site security.