The U.S. is committed to cleaning up Tijuana River pollution. Will California follow through?
San Diego leaders are calling on California to take stronger action to address the ongoing environmental crisis caused by sewage and industrial pollution flowing from the Tijuana River.
In summary
San Diego leaders are calling on California to take stronger action to address the ongoing environmental crisis caused by sewage and industrial pollution flowing from the Tijuana River.
As Tijuana River sewage has contaminated neighborhoods in southern San Diego County, the federal government has pledged two-thirds of a billion to clean it up.
Now local lawmakers are calling on California to step up the fight against cross-border pollution, and one introduced a bill this week to revisit air quality standards for noxious gas from the river.
State Sen. Catherine Blakespear held a joint hearing of the Senate Environmental Quality Committee and the Assembly Environmental Safety and Toxic Materials Committee in San Diego Thursday to explore how the state can help solve the problem.
“California has long been a national leader in environmental stewardship and policy making,” Blakespear said at the hearing. “But what is happening in the Tijuana River Valley is an international environmental disaster that undermines everything that California stands for.”
The hearing at Scripps Institution of Oceanography in La Jolla, convened scientists and civic leaders to discuss how failed infrastructure, industrial waste and decades of neglect created the environmental disaster, and what it will take to fix it.
“Due to its international nature, we know the federal government must take the lead,” Blakespear said. “Still, there is much that the state and local governments can do.”
After decades of stalemate, action on Tijuana River pollution is speeding up. The U.S. Environmental Protection Agency on Monday announced a new agreement with Mexico to plan for wastewater infrastructure to accommodate future population growth in Tijuana.
On Wednesday State Sen. Steve Padilla introduced a bill to update state standards for hydrogen sulfide, a noxious gas with a rotten egg smell that’s produced by sewage in the river. Residents in the area complain of headaches, nausea and other ailments when hydrogen sulfide reaches high concentrations. The bill would require the California Air Resources Board to review the half-century-old standard and tighten it if needed.
State Lawmakers also aim to improve conditions for lifeguards and other workers exposed to pollution, and hold American companies accountable for their role in contamination of the river. County officials will conduct an extensive health study to measure effects of Tijuana River pollution, and are making plans to remove a pollution hot spot in Imperial Beach.
Ongoing, chronic pollution
Sewage spills in south San Diego County became common in the early 2000s, sickening swimmers and surfers at local beaches. Then the aging wastewater plants failed, sending hundreds of millions of gallons of raw sewage into the ocean. Last year Scripps researchers found that the river is harming nearby communities by releasing airborne chemicals including hydrogen sulfide gas, which smells like rotten eggs.
“The sewage flowing into San Diego County’s Coastline is poisoning our air and water, harming public health, closing beaches, and killing marine life,” Blakespear said.
San Diego officials have successfully lobbied for federal investment to upgrade aging wastewater treatment plants. They also introduced faster water quality testing and surveyed residents to understand health issues.
Paula Stigler Granados, a professor of public health at San Diego State University, said studies of people living near the Tijuana River found “more scary stuff,” with 45% experiencing health problems, 63% saying pollution disrupted their work or school and 94% of respondents reporting sewage smells at home.
“Children are waking up sick in the middle of the night,” she said. “This is an ongoing, chronic exposure, not a one-time event.”
A section of the Tijuana River next to Saturn Boulevard in San Diego on Nov. 21, 2025. Photo by Adriana Heldiz, CalMatters
Water samples revealed industrial chemicals, methamphetamine, fentanyl, restricted pesticides, pharmaceuticals and odor-causing sulfur compounds, she said.
“This is absolutely a public health emergency,” Stigler Granados said. “I do think it is the biggest environmental crisis we have in the country right now.”
That sense of urgency isn’t universal. Last year Gov. Gavin Newsom declined requests by San Diego officials to declare a state of emergency over the border pollution problem, saying it “would have meant nothing.”
Over the last two years State Sen. Steve Padilla has introduced legislation to fund improvements to wastewater treatment, limit landfill construction in the Tijuana River Valley and require California companies to report waste discharges that affect water quality in the state, but those bills failed. He said the problem is overlooked in this border area, with its low-income and working class population.
“This is one of the most unique and acute environmental crises in all of North America,” Padilla said. “It is underappreciated simply because of where it is occurring.”
Tijuana River solutions
This year the U.S. repaired the failing South Bay International Wastewater Treatment Plant and expanded its capacity from 25 million to 35 million gallons of wastewater per day. In April, Mexico repaired its Punta Bandera plant near the border, reducing sewage flows into the ocean.
But the Imperial Beach shoreline has remained closed for three years, and residents still complain of headaches, nausea, eye irritation and respiratory ailments from airborne pollution. That problem is worst at a point known as the Saturn Blvd. hot spot in Imperial Beach, where flood control culverts churn sewage-tainted water into foam, spraying contaminants into the air.
“When the water is polluted you can close the beach,” said Kim Prather, an atmospheric chemist at Scripps, who identified the airborne toxins. “But you can’t tell people not to breathe.”
Community members feel forgotten by state leaders as they face chronic air pollution and years of closed beaches because of contaminated wastewater from the Tijuana River, said Serge Dedina, executive director of the environmental organization WildCoast and former Imperial Beach mayor.
“What they say is ‘how come California doesn’t care about us?’” Dedina said.
As federal authorities plan expansions to the South Bay International Wastewater Treatment Plant that will boost its capacity to 50 million gallons per day, local and state leaders have their own action plan.
A top priority for Aguirre is removing culverts at the Saturn Blvd. hot spot that cause airborne pollution.
“That’s low hanging fruit that we don’t need to depend on the federal government to fix,” Aguirre said.
She hopes to get funding for that project from Proposition 4, the state environmental bond that voters passed earlier this year. It dedicates $50 million to cleaning up degraded waterways, including the Tijuana River and New River, which flows into the Salton Sea.
The county is also planning a health study that would include physiological measurements to determine the health effects of Tijuana River pollution.
“What we’re working on is how are we going to take real, hard medical data and follow a cohort of people who live in this environment, so we can understand what is happening in their bodies,” Aguirre said. “What is happening to children and seniors? What is in their bloodstreams?”
San Diego County has distributed about 10,000 home air purifiers to households near the Tijuana River, but Aguirre wants to provide devices to all 40,000 homes in the affected area.
Dedina said his organization is removing waste tires that are exported to Mexico and wash back into the Tijuana River Valley.
“My lesson here is we need to stop the sediment, the tires, the trash, the toxic waste, the sewage,” he said.
In addition to his bill updating hydrogen sulfide standards, Padilla said he’s exploring legislation to regulate pollution created by California companies operating through maquiladoras in Mexico. He wants to work with Mexico “to put some pressure on them to basically clamp down on American companies that are licensed to do business here in California.
Blakespear said she wants to protect lifeguards and other public workers exposed to pollution.
Whether the solution is creating environmental standards for international businesses or funding costly infrastructure, lawmakers acknowledge that the binational nature of the problem makes it tough to solve.
“The complexity around it being an international issue and being a federal issue has added to the difficulties about who should act,” Blakespear said.
