Irrigation Subsidy Reduction Act of 2005

Irrigation Subsidy Reduction Act of 2005 - Amends the Reclamation Reform Act of 1982 to direct the Secretary of the Interior, for each parcel of land to which irrigation water is delivered or proposed to be delivered, to identify a single individual or legal entity as the owner, lessee, or operator.

Allows irrigation water to be delivered at less than the normal per-acre cost to either: (1) a qualified recipient that reports gross farm income from a single farm operation in excess of $500,000 per taxable year; or (2) a limited recipient that received such water on or before October 1, 1981, and that reports gross farm income in excess of such amount.

Requires lessees (currently, only owners and operators) of an irrigation district to furnish such district a certification of compliance. Allows the Secretary to require a lessee or operator to submit for examination a copy of a tax return for any taxable year in which the single farm operation of the lessee or operator received irrigation water at less than full cost.

Repeals a provision exempting from federal reclamation ownership and cost pricing limitations district lands held in trust for a beneficiary whose interests in the lands served do not exceed such limitations.

Directs the Secretaries of the Interior, the Treasury, and Agriculture to enter into a memorandum of understanding to grant the Secretary of the Interior access to and use available information collected or maintained by either the Department of the Treasury or Agriculture that would aid in enforcing federal ownership and pricing limitations.