| Summary: | For many years, untreated wastewater originating in Tijuana, Mexico, has entered the United States, largely via the Tijuana River. Tijuana's sewage system does not have the capacity to treat all of the city's wastewater, and some areas of the city are not connected to the sewer system. Tijuana's higher elevation results in sewage flowing downhill into California and out to the Pacific Ocean, causing beach closures in southern California. In the 1990s, the U.S. and Mexican Sections of the International Boundary and Water Commission collaborated with the U.S. Environmental Protection Agency (EPA) to address the problem by constructing the South Bay International Wastewater Treatment Plant (SBIWTP) in San Ysidro, California. The SBIWTP began providing the first level of treatment, known as primary treatment, to 25 million gallons per day (mgd) of Mexican wastewater in 1997. However, the part of the facility that would have provided secondary treatment, allowing the wastewater to meet Clean Water Act (CWA) standards for discharge into the Pacific Ocean, was not constructed due to a lack of funding and legal challenges. As a result, water discharged from the SBIWTP is only partially treated and has never complied with the requirements of the CWA. Over more than a decade, the U.S. Section of the International Boundary and Water Commission (USIBWC) has considered a variety of alternatives to bring the wastewater into CWA compliance, and now faces a federal court order requiring it to achieve CWA compliance by September 30, 2008. The USIBWC is currently considering two proposals: (1) upgrading the SBIWTP to provide secondary treatment at the existing plant site, or (2) building a new plant in Mexico where wastewater that received primary treatment at the SBIWTP would be pumped for secondary treatment, as proposed by Bajagua, LLC. Under both proposals, the treated effluent would be pumped into U.S. waters of the Pacific Ocean through a pipeline known as the South Bay.
Ocean Outfall, a facility used by both the USIBWC and the City of San Diego. In response to an explanatory statement of the House Appropriations Committee that accompanied the 2008 Consolidated Appropriations Act, GAO (1) described the two proposed treatment alternatives, (2) described the estimated costs and timelines for each proposal, and (3) assessed the reliability of these estimates. The explanatory statement directed GAO to report to the Appropriations Committees within 120 days of enactment of the law, which occurred on December 26, 2007. On April 7, 2008, GAO briefed members of Congressional staffs on our findings. This letter summarizes the main points from our presentation.
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