Local officials in San Diego and Imperial Beach are urging the U.S. government to threaten drastic action against the country’s neighbor and longtime ally unless Mexico finally cleans up the transborder sewage mess spewing from Tijuana.
That action – purportedly under discussion in the Trump administration – could include cutting off Tijuana’s primary water supply and restricting cross-border commerce.
When San Diego County adopted a measure urging the federal government to put more pressure on Mexico last week, Supervisor Jim Desmond voted against it saying the language and threats weren’t strong enough.
“We’re over being afraid of hurting their (Mexico’s) feelings,” Desmond told the board of supervisors on June 3. “We gotta come across with some tough language. We’re done being nice … We gotta stop the sewage, stop the flow.”
Meanwhile, Coronado is considering a similar resolution.
While city leaders contend severe sanctions against Mexico are overdue, some experts say those cutting off water or cross-border commerce would not only wreak havoc in Tijuana, but could have destructive economic, social and diplomatic consequences for both nations.
Stephen Mumme, a recently retired Colorado State University political science professor, said he doesn’t think cutting off the water will have the intended effect either.
The question is whether you need to use bully tactics to lean on Mexico to get these other projects done.
Stephen Mumme, retired Colorado State University political science professor
“The question is whether you need to use bully tactics to lean on Mexico to get these other projects done,” Mumme said.
“We have to make it their problem, right now it’s not. They flush it and it’s our problem,” added Desmond.
Why do cities support this proposal
The International Boundary and Water Commission’s South Bay International Wastewater Treatment Plant (SBIWTP) had been trying to receive funding for years to expand and rehabilitate the dilapidated plant.
In December, the Biden administration signed a bill that set the stage for more than $250 million in additional upgrades for the plant.
Before Biden’s bill, the IBWC had received a total of $400 million coming from funding from the EPA and March’s 2024 appropriations bills.
The total amount projected for the plant to be repaired and expanded was $600 million, which after Biden’s allocation, covered the entire cost of the project.
In addition to this project, Mexico is working on their side of the sewage issue.
A Mexican wastewater treatment plant in Tijuana, the San Antonio de los Buenos (SAB) wastewater treatment plant, that for years was allowing billions of gallons of effluent into the Pacific Ocean, finally went online after over a year of reconstruction this April.
There are several projects across the border that have yet to be started or even completed, including the international collector project. The international collector is a pipeline that spans from Tijuana to San Diego and routes Mexico’s wastewater to a plant in South Bay.
In the past year, environmental groups, South Bay residents and others — including Coronado Unified School District — have filed lawsuits against Veolia, a company that operates the South Bay plant.
“We’ve now moved from lawsuits to economic sanctions and restrictions,” said Carlos A. de la Parra, managing partner at Centro Luken de Estrategias en Agua y Medio Ambiente, who believes lawsuits are not going to resolve this.
Imperial Beach encourages Coronado
Imperial Beach passed a resolution 4-1 on April 16 that urges the restrictions on water exportation and cross-border traffic. Mayor Paloma Aguirre opposed the measure.
Coronado followed suit on May 6, voting 5-0 to amend the city’s current resolution on the sewage crisis with similar language.
We openly admit, even in our resolution, that both sides of this equation have failed – failed us and failed the Mexican people.
Jack Fisher, Imperial Beach council member
“We openly admit, even in our resolution, that both sides of this equation have failed – failed us and failed the Mexican people,” said Jack Fisher, an Imperial Beach council member, at the April 16 City Council meeting.
The Imperial Beach City Council members said they were tired of continuous conversation and they wanted action. There have been a few treaties signed with Mexico that Fisher mentioned, including the 1944 Water Treaty and the U.S.-Mexico agreement in 2022, but he said it isn’t enough.
“I’m sorry, but you know, the friends to the south of us are bad neighbors at this point,” Fisher said. “Sometimes you have to take drastic action. And we’re asking for the action to take place at the highest levels of government.”
Aguirre agreed with the resolution calling for halting water to Tijuana, but brought up concerns on some language used in the resolution that she felt would send the wrong message on immigration when the issue to focus on is health and environmental concerns.
Imperial Beach’s resolution calls for restricting commercial border traffic.
“We run the risk of politicizing it when we start to talk about immigration and border crossing on something that is absolutely a public health crisis,” said Aguirre.
McKay then attended Coronado’s City Council meeting on May 6 to talk about the resolution his city had just passed and to urge Coronado to do the same.
Officials weighing in
Coronado Mayor John Duncan announced at the May 6 meeting that he had communicated with William “Chad” McIntosh, the new U.S. commissioner of the International Boundary and Water Commission (IBWC), and said he had been working closely with the Trump administration’s Environmental Protection Agency to include an executive order and a declaration of emergency from the president.
An executive order regarding solutions to the trans-border sewage crisis is under consideration at the White House.
Coronado Mayor John Duncan
“An executive order regarding solutions to the trans-border sewage crisis is under consideration at the White House,” Duncan said. “Additionally, potential options for the executive order include specifics to hold Mexico accountable for its obligations to treat and control the sewage flows, ways to expedite the expansion of the U.S. treatment plant, a declaration of emergency as well as alternative means to treat the sewage flows prior to them entering the ocean.”
The White House press office said it had nothing to share regarding the Tijuana sewage issue.
The Trump administration is not new to the Tijuana sewage problem. This was on the table when President Trump served his first term.
The United States-Mexico-Canada Agreement (USMCA), signed by Trump, included $300 million for the cross border pollution, including the expansion of the South Bay plant.
U.S. Rep. Scott Peters, whose district includes Coronado and has been outspoken about this issue, said he’s worked for years with local, state and federal partners, regardless of party affiliation, to bring attention and secure funding for the crisis. “Now my congressional colleagues and I are focused on forging real solutions to ensure the long-term health of our region.”
CILA, the Mexican section of the IBWC, declined to comment and said it directs all American media outlets to speak with U.S. officials.
McIntosh, who was appointed to serve as the new commissioner in April, said in a release by the IBWC that the agency is working with the administration and the EPA on a “permanent and total solution to the Tijuana River pollution problem.”
“Besides requiring Mexico to take concrete and measurable steps to keep sewage out of the Tijuana River, we have started the rehabilitation and expansion of the South Bay International Wastewater Treatment Plant,” McIntosh said in the statement.
Mexico has also completed phase I of the international collector. Meanwhile the IBWC is rehabilitating and expanding its South Bay International Wastewater Treatment Plant up to a 50 million gallons per day treatment capacity, currently on track to 35 million gallons per day in 100 days.
This announcement came days after EPA Administrator Lee Zeldin visited San Diego and saw how the cross-border pollution impacts the Tijuana River Valley and local communities, including Coronado.
“This week, EPA transmitted to Mexico a proposed ‘100% solution’ that would PERMANENTLY END the decades-old crisis of raw sewage flowing into the U.S. from Mexico,” Zeldin said in a post on X on May 9. “Next, technical groups from both nations will be meeting to work through the details necessary to hopefully reach an urgent agreement.”
On May 15, Zeldin told the House Committee on Appropriations about EPA’s proposal for Mexico.
“We want to know whether or not they agree with the 100% solution,” he said. “If they are only willing to agree to an 80% solution, then we are not there yet and we will need to use other tactics to get a 100% solution done.”
Zeldin did not say what comprises his “100% solution,” and no one with the EPA, White House, IBWC or Mexican government has been willing to describe the U.S. proposal.
Yet, during Zeldin’s April press conference, he acknowledged that San Diego County residents are desperate to put the sewage crisis in their rearview mirror.
Commercial border traffic proposal
Mexico is a longtime U.S. ally and trade partner.
The Office of the United States Trade Representative says that in 2024, Mexico was the second-largest destination for United States exports and the top source of U.S. imports totalling a $839.9 billion goods trade.
Dr. Paul Ganster, director emeritus of the Institute for Regional Studies of the California’s at San Diego State University, who spent his career studying the U.S.-Mexico border region, thinks restricting commercial border traffic would not be helpful to the U.S.
“I mean, who benefits from northbound commercial traffic?” he asked rhetorically. “(Trump’s) given to these kinds of bold, high-visibility policy decisions that aren’t always grounded in fully understanding the complexities of the local circumstances.”
Aguirre said efforts to address the Tijuana sewage crisis have so far been nonpartisan, and it should stay that way. She wanted to take the conversation of immigration out of Imperial Beach’s resolution.
“I think it gets complicated,” the city’s mayor said. “There’s going to be unintended things that we may have not considered. We’re talking about essential workers, we’re talking about commercial – people bringing in their services.”
McKay argued that this was a lever he wanted to include that had to do with commerce, not immigration.
“It’s the movement of goods, which we know just like Otay Mesa East, is the nexus for more people, more business, more jobs, more wastewater,” McKay said of the other port of entry from Tijuana to San Diego.
I agree with 99% (of the resolution) except any discussion about limiting border crossings because that is the equivalent of shooting yourself in the foot … That will have severe economic impacts to us, forget about Mexico, to us [the U.S. and border region].
Imperial Beach Mayor Paloma Aguirre
“I agree with 99% (of the resolution) except any discussion about limiting border crossings because that is the equivalent of shooting yourself in the foot,” Aguirre told The Coronado News. “That will have severe economic impacts to us, forget about Mexico, to us [the U.S. and border region].”
Aguirre’s support for the other proposals include federal regulation and restriction on the export of potable water to the City of Tijuana.
“It potentially could be an opportunity to bring Mexico to the table and have those harder conversations. … This is the harsh reality that we’re living in and it can’t continue. So Mexico needs to do more. Our federal government needs to do more. Our state governor needs to do more and certainly the county,” she said ahead of the county’s measure.
Water proposal
About 90% of Tijuana’s water comes from the Colorado River, water that sustains a population of over 2 million inhabitants.
However, the U.S. Geological Survey says that only about 10% of all the water that flows into the Colorado River makes it into Mexico and most of that is used for farming.
Tijuana’s supply of the Colorado River is diverted from the Morelos Dam at the California and Baja California boundary, which is south of Yuma, Arizona. Water is then transported through the Alamo Canal to Mexicali, and then through the Tijuana Aqueduct to Tijuana. This water will travel about 150 miles.
Tijuana’s water comes from the Colorado River. It’s fundamentally their only water source.
Maria Elena Giner, past IBWC Commissioner
“Tijuana’s water comes from the Colorado River. It’s fundamentally their only water source,” said Maria Elena Giner, past IBWC Commissioner.
In San Diego, the Colorado River makes up about 50% of the imported water supply for the county, according to Padre Dam Municipal Water District. Although most of Tijuana’s water comes from the Colorado River, many San Diegans rely on this flow as well.
Ganster thinks cutting off water will not have the desired effect, and it’s not about just “turning a switch off.” But he does think the Trump administration could raise the level of urgency to encourage a more proactive approach from Mexico.
“I think that’s a proposal that doesn’t take into account the realities of the treaty of U.S. and Mexican law, and simply the physical problems of shutting off the Colorado River,” Ganster admitted.
De la Parra, who has more than 30 years of experience in water and natural resources management, agreed: “There is no way the U.S. federal government can restrict the water for Tijuana, so why would there be a proposal like that?”
If the U.S. tried to cut off water, they would be violating the 1944 Water Treaty, said Ganster.
Giner also said the U.S. has never violated the treaty.
The San Diego Union Tribune reports Mexico is already facing pressure from the Trump Administration when earlier this year the U.S. refused to send water from the Colorado River to Tijuana following Mexico’s delay in water deliveries to the Rio Grande (“Rio Bravo” in Spanish) which Texas agriculture relies on.
De la Parra explained Mexico’s allocation was simply delivered in the usual fashion, at Presa Morelos (the Morelos Dam), rather than diverting the requested volume to a different delivery point requested by Mexico.
“This, however, is not a violation of the treaty by the U.S..” he noted. “Mexico’s legal allocation was delivered, just not through the method preferred by Mexico.”
But Ganster is not sure actually cutting off Tijuana’s water is possible.
“I’m not sure physically how it could be done,” Ganster said. “Basically, the U.S. would have to shut off Colorado River flow … but that would hurt a lot of U.S. downstream users as well.”
That would cause some issues, in terms of relationships, between the two (countries) … It would have a very negative impact. It would basically put the U.S. in a position of not respecting a formally signed legal treaty with another sovereign nation.
Paul Ganster, retired San Diego State University professor
“That would cause some issues, in terms of relationships, between the two (countries),” Ganster theorized. “It would have a very negative impact. It would basically put the U.S. in a position of not respecting a formally signed legal treaty with another sovereign nation.”
De la Parra said a cut-off would violate an international treaty that was ratified by each nation’s federal senates.
Ganster believes Mexico and the United States share blame for the sewage dilemma, with a lack of funds allocated by both governments and a lack of responsibility from the U.S. in terms of Tijuana’s rapid growth.
“Many observers over the years pointed out that a significant part of that growth is due to the location of manufacturing in places such as Tijuana, which in large part represents investment by U.S. companies,” Ganster said.
“U.S. companies are taking advantage of low-cost and skilled and plentiful labor … But they’re not really contributing to the infrastructure problem on sewage treatment. They’re getting a pass on that,” he continued.
Mumme, whose work has centered on water and environmental management along the U.S.-Mexico border, believes Mexico really wants to cooperate with the U.S.
He said he hasn’t seen anything that suggests the opposite. “But they have their own practical limitations and fiscal limits and their other demands on their resources.”
Other considerations
Ensenada resident Mario Zepeda Jacobo could not fathom the U.S. restricting water to the city of Tijuana.
“It is water that Mexico receives from the Rio Colorado, it is Mexico’s water and they distribute it … to each city,” said Zepeda Jacobo, president of Consejo Ciudadano B.C., a non-profit promoting citizens’ participation in economic and social decisions statewide and coordinator of the group’s water commission.
De la Parra explained that a 1967 agreement, IBWC Minute 225, intended to channelize the river to send all drainage and floodwater directly into the ocean. The channelization was well underway in Mexico by 1980, but abandoned by the U.S., he asserted.
As a result, every single drop that gets into the river is streamlined all the way across the border and unfortunately delivered to the estuarine reserve, he said.
The pollution coming from Tijuana is not by accident. It’s by design.
Carlos A. de la Parra, managing partner at Centro Luken de Estrategias en Agua y Medio Ambiente
“The pollution coming from Tijuana is not by accident. It’s by design,” he added.
Throughout Tijuana, “aguas negras” (raw sewage) can be found seeping through uncovered manholes or as discharges from unhooked homes in multiple colonias – human and industrial wastes that eventually make it into the river.
“The problem is spread throughout the city. There are sewer leakings in many places. There are unhooked settlements (colonias) that have not been hooked up to the sewer system … You can repair in gold plate the South Bay treatment plant, but if the water doesn’t get to the sewer, it’s not going to get to the plant …”
Carlos A. de la Parra
“The problem is spread throughout the city. There are sewer leakings in many places. There are unhooked settlements (colonias) that have not been hooked up to the sewer system,” de la Parra noted. “You can repair in gold plate the South Bay treatment plant, but if the water doesn’t get to the sewer, it’s not going to get to the plant …”
According to Giner, Tijuana homes and businesses that are not connected with the city’s wastewater system constitute a violation of Minute 283, a bilateral agreement that says Mexico “will assure that there are no discharges of treated or untreated domestic or industrial wastewaters into waters of the Tijuana River that cross the international boundary…”
“It’s a combination of lines that are collapsed and lines that don’t have a wastewater treatment plant to go to,” she added.
For de la Parra, an academic studying water and environmental issues on the Mexico-United States border for over three decades, a solution cannot occur until all stakeholders turn to experts and develop an agreement that identifies a “rational, fact-based approach” such as binational coordination to solve water quality, sediment and sand solid waste problems.
He said Minute 320, a U.S.-Mexico agreement in 2015, had that intention: to empower local agencies responsible for water management on both sides of the border via respective federal governments and encourage cooperation to follow-up on agreements and develop plans jointly.
Funding from the USMCA crushed all progress of this binational core group, he said, moving the issue back to square one.
“It’s a complex problem and you need to treat it as such. If you decide to treat it in a very infantile way, you will get childish results and childish scenes of people screaming at each other,” said de la Parra.
Millions of people affected
Giner said cutting off Tijuana’s water would have a negative impact on millions.
“Imperial Beach is arguing,” she said, “‘Well, if we take away their water, then we won’t get their pollution,’ because if you don’t have water to flush toilets, there’s going to be no waste water.”
Gabriela Guinea-Johnston, a Playas de Tijuana resident and years-long advocate for clean beaches, argues that binational collaboration should be the priority.
“This will garner opposition from the people,” said Guinea-Johnston about Imperial Beach’s proposal, speaking in Spanish. “Restricting the water, which is the foundation of life, I believe, is an inhumane solution. They are not seeing the reality people are living in.”
“That’s a pretty serious measure,” echoed Irasema Coronado, director and professor at Arizona State University’s School of Transborder Studies. “You can’t live without water. I mean this is absolutely a terrible scenario.”
Coronado calls this a longstanding problem and says it requires a very comprehensive solution and reciprocated good will.
The government of Mexico and the government of the United States need to come together to find a solution that has resources, that has the best science and technology behind it, and the community is involved … Otherwise, it’s not going to work.”
Irasema Coronado, director and professor at Arizona State University’s School of Transborder Studies
“The government of Mexico and the government of the United States need to come together to find a solution that has resources, that has the best science and technology behind it, and the community is involved,” said Coronado. “Otherwise, it’s not going to work.”
