Large pipe rupture in Tijuana causes spill into San Diego on Feb. 10, 2023. / Courtesy of CESPT
Large pipe rupture in Tijuana causes spill into San Diego on Feb. 10, 2023. / Courtesy of CESPT

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Construction workers in Tijuana accidentally blew a hole in a major pipe transporting the city’s sewage to a wastewater plant along the coast last Friday. 

That means, once again, untreated sewage has been flowing into San Diego.

While that wastewater plant, called San Antonio de los Buenos, is actually broken anyway, the rupture forced Tijuana to shut down virtually all of its important pumps that send sewage away from the border and toward the coast. When that happens, wastewater often escapes the collection system and drains untreated into natural channels like the Tijuana River or the canyons that make up the U.S.-Mexico border. 

An international wastewater treatment plant run by the International Boundary and Water Commission can take on extra sewage treatment when these kinds of accidents happen.

Morgan Rogers, who manages that plant, said Mexican officials are hoping to construct a temporary bypass pipe to restore sewage flow to their wastewater plant. But that won’t happen until at least the middle of next week. 

The cross-border spill at Smuggler’s Gulch, one of the notorious points for untreated sewage to make its way into San Diego, was trickling on Thursday.

Trent Biggs, a watershed scientist at San Diego State University who manages a new water quality gauge in the river, said the breakage was so far south in the Tijuana River watershed and much of the spill redirected to the international treatment plant, so their instruments didn’t show a major impact on water quality in the river. 

Smuggler’s Gulch in San Ysidro on Feb. 16, 2023.
Smuggler’s Gulch in San Ysidro on Feb. 16, 2023. / Photo by Ariana Drehsler

Commissioners from the United States and Mexico who lead their respective sides of the International Boundary and Water Commission met Wednesday to work out a temporary solution to cross-border flow. The U.S. side lent a specialized vacuum truck to help clean the area around the broken pipe and prep it for repairs.

U.S. officials had to loan Mexico equipment back in August when a key pair of sewer pipes snapped in half at the top of a large canyon, called Matadero, that drains into San Diego. The cause of that incident was again attributed to human error. Rogers said this latest spill is not nearly as bad as August’s, but all of these pipes make up the same sewer system that’s supposed to direct Tijuana’s sewage south of the city toward treatment. 

Mexican officials fixed one of the pipes at Matadero canyon but the other is still out of service. That means a large portion of Tijuana’s sewage diversion from the United States is largely dependent on that lone pipe holding out. 

This decades-old cross-border sewage crisis is largely due to aging and broken infrastructure in Mexico, and underinvestment in building larger treatment facilities on both sides of the border. Congress committed $330 million toward expanding the international treatment plant at the border. But financial commitments to fix Tijuana’s sewage system are not in place. 

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