FILE: Morgan Rogers at the South Bay Wastewater Treatment facility earlier this year. Staff photo by Madeline Yang.

The South Bay International Wastewater Treatment Plant (SBIWTP) does not discharge or divert untreated sewage into the ocean. 

While flows into the SBIWTP have averaged 8% above the plant’s design capacity over the past seven months, all flows into the plant are still treated and discharged through a pipeline to 3.5 miles offshore. 

Furthermore, environmental assessments in support of the SBIWTP expansion project’s Environmental Impact Statement (EIS), and based on 20 years of data, concluded that beach pollution sources are most likely originating from Tijuana River transboundary flows and the San Antonio de los Buenos Wastewater Treatment Plant (SAB) ocean discharge, not the SBIWTP.

The EIS report can be found here:

About 35M gallons discharged in Mexico

Transboundary flows down the Tijuana River that discharge into the ocean typically consist of treated water, potable water, groundwater, and wastewater, in addition to trash and solid wastes, all of which contribute to our beach pollution.

In addition, an estimated 35-plus million gallons per day of raw sewage are discharged year-round directly into the ocean south of the border at the site of Mexico’s defunct SAB plant.

Depending upon ocean currents, this raw sewage sometimes drifts north and contaminates
our beaches.  These are the most significant sources of ocean pollution within our coastal communities and beaches.

New plant set for 2026

A new plant at SAB is scheduled to be online in 2026, eliminating this source of pollution. 

One year ago, the International Boundary and Water Commission signed a U.S.-Mexico agreement known as Minute 328 to implement a list of sanitation projects in San Diego and Tijuana, including construction of the new SAB plant, doubling the capacity of the SBIWTP, and capturing raw sewage that currently flows into the Tijuana River.

Implementation of these projects is already underway and as they are completed over the next several years, untreated flows discharged to the ocean at SAB will be eliminated and the number of days of transboundary flows in the Tijuana River will be greatly reduced.

Morgan Rogers
Area Operations Manager, San Diego Field Office
US International Boundary & Water Commission

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Morgan Rogers is the Area Operations Manager, San Diego Field Office
US International Boundary & Water Commission.