Untreated wastewater originating in Tijuana, Mexico enters the U.S. via the Tijuana River. Tijuana¿s higher elevation results in sewage flowing downhill into Calif. and out to the Pacific Ocean. There are several alternatives to bring the wastewater into Clean Water Act compliance; a fed. court order requires compliance by Sept. 30, 2008. There are two proposals under consideration: (1) upgrading the Wastewater Treatment Plant in San Ysidro, Calif.; or (2) building a new plant in Mexico where wastewater that received primary treatment would be pumped for secondary treatment. This report: (1) describes the two proposed treatment alternatives; (2) describes the estimated costs and timelines for each proposal; and (3) assesses the reliability of these estimates.