Arkansas Valley Conduit Act - Directs the Secretary of the Interior to plan, design, and construct a water delivery pipeline, to be known as the Arkansas Valley Conduit, from a location in the vicinity of Pueblo Reservoir, Pueblo, to Lamar, Colorado.
Designates the Southeastern Colorado Water Conservancy District, or its designee that is recognized under State law as an entity that has taxing authority, as the lead non-federal entity for the Conduit. Directs such entity to: (1) act as the official agent of the Conduit; (2) pay the non-federal share of any increased costs, including construction costs, under this Act; and (3) pay costs for and perform the operations, maintenance, and replacement of the Conduit. Sets the federal share of: (1) total planning, design, and construction costs at 80 percent; and (2) any increased costs that are a result of fundamental design changes conducted at the request of anyone other than such entity at 100 percent. Directs the Secretary, upon completion, to transfer ownership of the Conduit to such entity.