GAO: Sewage Flowing From Mexico into U.S. Causes California Beach to Close – Every Year

Bruce Truax | March 11, 2020 | 2:30pm EDT
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The U.S. Mexico border near Imperial Beach, Calif.  (Getty Images)
The U.S. Mexico border near Imperial Beach, Calif. (Getty Images)

( -- Since 2003, sewage water flowing through the Tijuana River from Mexico into the United States has contaminated some public beach area in Imperial Beach in Southern California, forcing officials to close these areas for at least one quarter of the year and sometimes half the year, according to a report by the U.S. Government Accountability Office.   

Currently, the southern portion of the beach in Imperial Beach is closed because of the sewage from Mexico, according to the San Diego County website and Art Ayala, lieutenant of the Safety Department of Imperial Beach.


“After a heavy rainfall…the mist off those breaking waves has caused us, myself included, to [have some] ill-effects,” Ayala told CNS News by telephone.  “Anything from headaches to sore throats to sinus issues and that’s just from breathing…that air off the ocean…you can definitely smell sewage, rotten odors coming off the ocean.”

Ayala added that the sewage turns the ocean “brown.”

The GAO reported, “wastewater pipeline breaks in Mexico continue to send sewage across the border, and storm water from Mexico continues to carry trash from city streets, sediment, and bacteria into the United States. Stormwater runs off paved surfaces or other impervious areas into water bodies and may contain pollutants that the water picks up as it runs over such surfaces.”

“In the Tijuana River Valley watershed, from 2003 through 2017, officials from the City of Imperial Beach, California, closed public beaches for at least one-quarter of the year and up to half the year in some years due to sewage contamination, according to data from the city,” reported the GAO.


The report, International Boundary and Water Commission: Opportunities Exist to Address Water Quality Problems, released in February, says that poor infrastructure in Mexico has resulted in millions of gallons of untreated water coming into the United States across the border. This water contains sewage, heavy metals, and E. Coli. (p. 37

During periods of intense rain, Mexican-operated treatment plants, sewer systems, and sewage pipelines overflow into the Tijuana River, which flows across the border from Mexico into the United States. Because of the higher elevation on the Mexican side, the water flows from the south to the north.


Mexico operates a pump station named CILA -- Comision Internacional de Limites y Aguas -- which is along the Tijuana River.  As the GAO explains, “According to a 2019 study, Tijuana has not built sufficient sewage infrastructure to serve the area’s exponential population growth and urbanization. When problems arise with Tijuana’s treatment facilities, the city diverts a portion of its wastewater for treatment at the South Bay Plant in California.

“In these instances, the Mexican utility may also shut down Pump Station CILA, a main pump located in the Tijuana River that diverts the river to the treatment plant. If the South Bay plant is not notified and does not shut down its pump and canyon collectors, it may receive additional flows.”     


Trash buildup is also a cause for sewage flows. In January 2020, a trash buildup on a sewer drain caused putrid water to back up into Tijuana River. Then in June 2019, 1.9 million gallons of wastewater were released into the Tijuana River because of trash buildup at one of the pumps along the Tijuana River that caused the pump to fail. 

Storm water washes trash into the Tijuana River, and sewer systems near the Tijuana River. The USIBWC, U.S. Customs and Border Protection, and state park employees remove trash periodically from these areas. However, this action is not sufficient during intense rainfall.

The contaminated water flows into the Tijuana River, which flows across the border through the Tijuana Slough National Wildlife Refuge, where it empties into the Pacific Ocean a few miles north of the border, near the City of Imperial Beach, Calif.   

U.S officials say Mexico does not have the means to properly and consistently maintain and operate their pipelines and pumps, according to the GAO.  In 2019, 1.9 million gallons of wastewater flowed into the United States due to a sewage pipe spill. In February of 2017, a pipeline rupture near the Tijuana River sent 143 million gallons of sewage-contaminated water flowing into the U.S from Mexico, according to the report.

Sewage and toxic metals from Mexico have also flooded the streets of Nogales, Mexico, said the GAO.


As part of a 1944 treaty with Mexico, the United States agreed to treat some of the waste from Mexican sewer systems. For instance, an International Outfall Interceptor (IOI) pipeline connects Nogales, Mexico and Nogales, Arizona through a United States-operated waste treatment system.

Due to a poor sewer system, the streets of Nogales in Mexico flood during heavy rainfall. According to July 2018 Arizona Department of Environmental Quality (ADEQ) report, the citizens of Nogales, Mexico have lifted manhole covers to the sewer system to drain the streets. This overloads the sewer system and the sewage floods the U.S sewer system and then leaks into the streets of Nogales, Arizona.

In 2017, Santa Cruz County Health Services and the Arizona Department of Health issued notices of elevated levels of E. Coli due to untreated sewage leaking from the sewers.

(Getty Images)
(Getty Images)

It’s not just sewage that's flowing into the United States. Metal-plating factories in Nogales, Mexico dump heavy metals directly into the sewer system, and this metal eventually makes its way into the U.S sewage system.

Wastewater is also flowing from the Nogales Arizona International Outfall Interceptor pipeline (IOI) into the Santa Cruz River in Arizona.

The IOI is eroded and broken in several areas and no government entity is willing to maintain it. Currently, there is a dispute over who is responsible for the maintenance of IOI.

The U.S Commission that manages wastewater along the Mexican border (USIBWC) claims that the city of Nogales is responsible for its maintenance. However, Nogales city managers claim they do not have that responsibility.

In 2005, the USIBWC proposed a $50 million plan to fix the IOI. However, the project has not started due to funding disagreements between Arizona, USIBWC and the city of Nogales.

In its recommendations, the GAO said Congress should authorize the USIBWC to “identify alternatives” to fix the water quality problems in the Tijuana River Valley watershed. In addition, the GAO said the U.S. commissioner of the IBWC “should work with the Mexican Commissioner to formalize a binational rapid response team to address sewage infrastructure failures along the U.S.-Mexico border, including the Nogales and South Bay wastewater treatment plants.”

The commissioner should also direct “USIBWC staff to conduct long-term capital planning for the Santa Cruz River Basin and Tijuana River Valley watersheds.”

To read the GAO report, click here.

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