Arkansas Valley Conduit Act of 2008

Arkansas Valley Conduit Act of 2008 - Conditions the construction by the Secretary of the Interior of the Arkansas Valley Conduit, Colorado, on a contract providing for the payment within a specified period of 35% of the Conduit's cost that is comprised of revenue generated by payments pursuant to a repayment contract and revenue that may be derived from contracts for the use of Fryingpan-Arkansas project excess capacity or exchange contracts using project facilities.

Requires revenue derived from contracts for the use of Fryingpan-Arkansas project excess capacity or exchange contracts using project facilities to be credited towards payment of the actual cost of Ruedi Dam and Reservoir, the Fountain Valley Pipeline, and the South Outlet Works at Pueblo Dam and Reservoir until the date on which the payments for the Conduit begin, and then towards payment of the actual cost of the Conduit. Provides that nothing in federal reclamation law prohibits the concurrent crediting of revenue towards payment of the Conduit.

Requires any project rates charged for water for municipal, domestic, or industrial use or for the use of facilities for the storage or delivery of water to be adjusted to reflect the estimated revenue derived from contracts for the use of project excess capacity or exchange contracts using project facilities.

Authorizes appropriations for the construction of the Conduit. Prohibits such sums from being used for its operation or maintenance.