The Lower Republican River Basin Study Act - Authorizes the Secretary of the Interior to conduct a study to determine the feasibility of implementing a water supply and conservation project that will: (1) improve water supply reliability in the Republican River Basin between Harlan County Lake in Nebraska and Milford Lake in Kansas; (2) increase the capacity of water storage through projects that serve areas in the Republican River Basin; and (3) improve water management efficiency in the Republican River Basin and, where appropriate, evaluate integrated water resource management and supply needs in the Republican River Basin.