A quick fix to the Tijuana River pollution could offer immediate relief

from Deborah BrennanCalMatters

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Communities living with one of California’s worst pollution problems could see immediate relief if San Diego leaders can get a key Tijuana River project off the ground.

While millions of gallons of untreated sewage enter the river regularly, a road crossing known as the Saturn Boulevard Hot Spot is the source of most of the river’s airborne pollution.

While the US and Mexico are chasing a total of $800 million upgrading waste water facilities on both sides of the border, local authorities are working on a smaller adjustment to that air point that could improve conditions as early as next year, officials said.

San Diego leaders are trying to secure about $25 million to repair the Saturn Boulevard crossing, where sewage-polluted water is forced through aging culverts that spew hydrogen sulfide gas and other toxins into South San Diego.

Fixing the hot spot could “mitigate the turbulence in that area, which will mitigate the emissions that basically shoot aerosols into the air,” said San Diego County Supervisor Paloma Aguirre, who is spearheading efforts to clean up the river.

But they are still trying to find a source of funding for the project.

Sewage pollution from the transboundary river has plagued Imperial Beach, Coronado and other parts of south San Diego for decades. The threat grew as Tijuana’s population grew and treatment plants on both sides of the border failed, pouring hundreds of millions of gallons of raw sewage into the ocean in recent years.

San Diegans have long known that raw sewage in the ocean poses a danger to swimmers and surfers, and local beaches have been closed for years. Then in 2024, researchers at the UC San Diego Scripps Institution of Oceanography discovered that pollution doesn’t just pollute the water. It also polluted the air.

The river releases airborne chemicals, including hydrogen sulfide gas, that cause respiratory problems and other illnesses among people in neighboring communities.

Residents experience asthma, stomach problems, skin rashes and headaches without even entering the water. Parents are wary of letting children play outside. Local schools implement “rainy day schedules” to keep students inside when air quality deteriorates.

The researchers traced the air pollution to the Saturn Boulevard hot spot. This is a culvert located along a country road near the Tijuana River. The structure, which includes several large concrete pipes, was built decades ago to divert flooding from neighboring farms. When it rains, water flows across the road and gushes through the pipes, creating piles of foam and spraying pollutants into the air.

San Diego County officials are trying to secure money to fix that. They estimate it will cost about $25 million to redesign the site to control flood flow and prevent toxic gas and particulate matter from being released into the air.

There are several parallel paths to funding the project, but none of them are certain.

One is a bunch of money in Proposition 4, the $10 billion climate bond measure California voters approved in 2024. It includes about $50 million for border projects along San Diego’s Tijuana River and Imperial County’s New River.

Although it was two years ago, the funds have not been released due to administrative procedures that have delayed their absorption. This year state Senator David AlvarezDemocrat from San Diego, introduced legislation to cut red tape and expedite funding through the bond measure.

With the money available, the State Water Resources Board will accept grant applications for the funds this summer between June and August and then evaluate and award them by early next year, said Jennifer Toney, senior engineer for the State Water Resources Control Board. Local authorities and non-profit organizations working on these rivers are eligible to apply.

The board can award up to $20 million for construction like the Saturn Boulevard project, Conti said. But it faces competition from other possible efforts on the Tijuana River, such as sediment removal, trash capture and others, as well as proposed projects along the Nova River, Toney said.

On a separate note, state lawmakers filed a request in this year’s state budget for $23 million to cover most of the Saturn Boulevard construction. If approved, it could free up bond money for other border river projects.

A third possible source of funding is a proposed half-cent county sales tax titled “Protecting the San Diego County Health and Safety Act,” which goes to voters in November. It could generate $360 million a year, with about $80 million of that earmarked for improvements to the Tijuana River.

The measure calls for up to 22.5 percent of tax revenue to be spent on environmental mitigation to address the “toxic wastewater crisis in the Tijuana Valley.” But it doesn’t lay out specific projects like the Saturn Boulevard site, KPBS reported.

Meanwhile, an even faster temporary fix, expected to cost $2.5 million, could be in place by this time next year. The temporary fix will extend existing pipes and transfer flowing water downstream through a closed system, county Public Works Director Marissa Barry said in an email to CalMatters. This will reduce the scattering that causes pollutants to become aerosolized.

“The team evaluated infrastructure mitigation options at the Saturn Boulevard hotspot and agreed to move forward with a short-term solution that would offer tangible immediate benefits,” Barry said.

Design, environmental analysis and permitting for that project are currently in the works, Barry said. Construction should take about three months, and county officials hope to complete it by March 2027, ahead of the area’s bird nesting season.

Aguirre warned that the reconstruction of the culvert would not clean up the river but would reduce its impact on neighboring communities. “This is not a permanent solution to the entire crisis. This is something we can address by working with the state, city and county of San Diego, which we know based on empirical evidence will bring some relief to the residents of the affected areas.”

This article was originally published on CalMatters and is republished under Creative Commons Attribution-NonCommercial-No Derivatives license.