In November 2010, the South Bay International Wastewater Treatment Plant (SBIWTP) was upgraded from primary to secondary treatment to conform to the Clean Water Act (CWA). In this study, statistical comparisons were made of the bacterial water quality (total and fecal coliforms and enterococci densities), both before and after discharge of secondary treated sewage to the SBOO began, so that the effect of this treatment upgrade on ocean water quality could be quantitatively assessed. The frequency of exceedance of bacterial indicator thresholds was statistically analyzed for 11 shore, 7 kelp, and 21 offshore stations throughout US and Mexico using the Fischer’s Exact test, for the years before (2001- 2010) compared to after the secondary discharge began (2011-2018). It was determined that the 2 offshore stations that showed significant (p

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.