The U.S. International Boundary and Water Commission (IBWC) this month told the San Diego Regional Water Quality Control Board that full expansion of the South Bay International Wastewater Treatment Plant is not expected until years after the 2027 date set by the U.S. and Mexico.
At a Water Board meeting on April 8, Board Member Betty H. Olson, also vice chair, asked an IBWC representative: “What are the chances that you actually update everything by the date you said, December of 2027?”
Gilbert Anaya, chief of the commission’s environmental management division, said quite a bit will be done by then, but the federal agency will not be done with the plant’s expansion until 2030.
“Fifty million gallons of secondary treatment right now is targeted for what’s in our contract, which is 2030,” Anaya told the San Diego Water Board.
That disclosure came as millions of gallons of untreated wastewater flow from the Tijuana River into the Pacific Ocean every day, causing the Coronado shoreline to experience intermittent beach closures. The ongoing sewage pollution crisis has resulted in impacts to the environment and public health in South San Diego, also affecting air quality and the local economy.
Initial expansion of the South Bay International Wastewater Treatment Plant (SBIWTP), to treat an additional 10 million gallons per day (MGD) of raw sewage, happened in August after the U.S. Environmental Protection Agency (EPA) and IBWC announced a fast-tracked 100-day interim expansion in May. While the plant’s treatment capacity was increased to 35 MGD, the EPA announced plans to increase capacity to 50 MGD of full secondary treatment by December 2027.
The EPA did not specify if the agency aligned with the timeline Anaya reported, and referred The Coronado News to the IBWC.
“This has been a top priority for President Trump and Administrator Zeldin, and they will not rest until the raw sewage flow from Mexico is stopped for good,” wrote a spokesperson with the EPA.
The commission said it has aggressively pushed to quickly complete improvements that will protect public health from exposure to Mexican sewage working closely with its partners at the EPA, noting the initial expansion.
“We are considering every available tool to ensure the South Bay plant expansion project is completed on time,” said the agency in a statement on April 22. “USIBWC takes this project seriously and is working to streamline project development to get it online as soon as possible for the betterment of the communities we serve.”
The phased expansion is part of Minutes 328 and 333 and a July 2025 memorandum of understanding signed by Lee Zeldin, EPA administrator, and Mexico’s secretary of the environment and natural resources, Alicia Bárcena Ibarra. Minute 333 intends to reduce cross-border sewage pollution from Tijuana through enhanced monitoring and planning for operation and maintenance of critical sites and systems that will account for future population growth in Tijuana.
Previously, the IBWC said the expansion, along with ongoing Minute 328 infrastructure projects, is expected to eliminate or significantly reduce the discharge of untreated wastewater and sediment to the Tijuana River and the Pacific Ocean.
Last month, representatives from the U.S. Small Business Administration visited San Diego to hear from business owners.
“I think they really got a good picture of what our community is going through and what we’re asking for,” said Imperial Beach Mayor Mitch McKay about a March 31 discussion with local business owners during a City Council meeting the following day. “We’re gonna be watching and looking for their return, responses and solutions. Hopefully we can make some real progress here in the near term.”
Discharge permit
On April 8, the San Diego Water Board voted to amend the IBWC’s National Pollutant Discharge Eliminations System (NPDES) permit of waste discharge requirements entering the Pacific Ocean from the plant through the South Bay Ocean Outfall (SBOO).
“The treatment of up to 10 MGD of additional flow at the SBIWTP will result in improved water quality in the lower Tijuana River, Tijuana River Estuary, and near shore coastal waters,” says the amended permit. “Absent the treatment at the SBIWTP, these flows would remain untreated in the River due to insufficient capacity in Tijuana’s municipal wastewater conveyance and treatment system.”
According to Riley Nolan, water resource control engineer at the San Diego Water Board, the amended permit authorizes the 10 MGD expansion beyond the current permit’s expiration on June 30 while board staff work toward reissuing the permit to authorize a full 50 MGD of secondary treatment in accordance with the timeline laid out by the federal government.
Before the board’s approval, Nolan noted that the amendment comes “at a time that we’re seeing really chronic dry weather transboundary flows in the Tijuana River.”
The amendment comes after the San Diego Water Board adopted Cease and Desist Order No. R9-2025-0139 which required the boundary commission to comply with a number of remedial and preventative actions to minimize impacts to the treatment plant, the SBOO and ocean.
Nolan said the order last year did not actually authorize the 10 MGD expansion, but rather established interim effluent limitations, with which the commission is required to comply.
According to Nolan, the IBWC has not yet treated a sustained 35 MGD over the course of a month at the plant due to critical work on a key structure that controls raw sewage entering the plant.
Nolan explained IBWC has a history of noncompliance prior to November of 2024 stemming from a lack of maintenance and investment in the plant as well as storm damage from Tropical Storm Hillary.
“Since then, between November 2024 and August of 2025, when the board issued its most recent cease-and-desist order related to the expansion, IBWC had only two exceedances of effluent limitations at that time,” said Nolan. “IBWC has complied with all requirements outlined in the 2025 cease-and-desist order.”
Ongoing projects
The SBIWTP, near the U.S.-Mexico International border, is operated by Veolia Water North America. According to Anaya, the IBWC and Veolia have signed a new five-year contract and progress continues for Minute 328 projects.
“There are four projects scheduled to begin in ‘27 and (they) may not be done by that time, but they will be well on their way towards implementation,” said Anaya. “And those projects have more (of) an effect on the transboundary flow in the Tijuana River.”
According to Anaya, spikes in hydrogen sulfide levels will be addressed with the startup of PBCILA, which resumed operations on April 6.
The IBWC announced the Mexican section of the commission resumed operations with the goal of reducing cross-border flows through the Tijuana River in a press release on April 7.
According to the release, pump operations were suspended last year on Nov. 15 to protect equipment after heavy rainfall in the area. The release said ongoing sediment removal occurred since March. With the system back online, the plant can resume receiving up to 35 million gallons a day from the Tijuana sanitation system, it continued.
During a Coronado City Council meeting that day, Coronado Mayor John Duncan brought up resumed operations and said he meets with relevant IBWC stakeholders to talk about the status of construction and funding to support lobbying efforts.
According to Duncan, the Coronado Cays neighborhood is being impacted by hydrogen sulfide odors from the untreated sewage.
“The press release this morning was kind of a surprise,” said Coronado Council Member Kelly Purvis, on April 7. “I didn’t know that the pumps weren’t running. I don’t know if anybody else was notified, but I didn’t know.”
