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CBP's Sampling of Tijuana Wastewater

Document Posting Date: 
August 7, 2018

The watershed for the Tijuana River flows from Mexico into the United States before entering the Pacific Ocean. There is a significant amount of raw sewage and other unknown contaminants in the transborder flows, which have extremely high levels of bacteria. During the dry season, all water is supposed to be diverted to treatment plants leaving the riverbed dry. During the rainy season, the volume of water overwhelms the collection system, and wastewater flows through the riverbed to the ocean. This presence of wastewater and high levels of bacteria cause beach closures at Imperial Beach, California almost half of the year. 

The river basin is uninhabited and a common route for illegal border crossings.  As such, U.S. Customs and Border Protection (CBP) must operate in this area to intercept such activity despite the presence of wastewater.  In 2017, CBP noticed an increasing presence of wastewater during dry weather and launched a response to mitigate the effects on the agency’s operations. 

CBP conducted a six month sampling effort to add to already existing data-sets collected by International Boundary and Water Commission (IBWC) and other past sampling efforts. CBP’s data collection is intended to complement existing data, giving a potentially new perspective on the issue.  The goal is a better understanding the impact of wastewater on CBP operations in this area.  Below are the laboratory analysis of monthly samples of wastewater.

Last modified: 
June 12, 2019