Background
Nearly three-quarters of the Tijuana River Watershed is in Mexico, but it drains into the Pacific Ocean through the 8 square-mile Tijuana River Valley north of the border in Imperial Beach. The Tijuana River Valley is a natural floodplain with tidally flushed wetland and riparian areas that support threatened and endangered species and includes several federally listed historical and archaeological sites. The river valley includes a tidal saltwater estuary at the mouth of the Tijuana River and sandy beaches along the Pacific shoreline to the west.
The Tijuana River Valley is located between two heavily populated urban areas, the City of Tijuana in Mexico and the cities of Imperial Beach, Chula Vista, National City, San Diego, and Coronado in the United States. Untreated wastewater flows, contaminated sediment loads, and trash influxes plague the Tijuana River watershed, adversely impacting the affected environment, surrounding communities, and overall public health and safety of the region.
The transboundary pollution enters Californian waters through several pathways:
- Pollution comes through the Main Channel of the Tijuana River, a concrete channel that flows directly to the Tijuana River Estuary and the Pacific Ocean and is intended to accommodate wet-weather flows.
- Pollution also enters through the Canyon Collectors, a series of concrete channels and basins that collect wastewater flowing through border tributaries and are intended to pump that wastewater to a treatment plant.
- Pollution is discharged directly into the ocean in Mexico, just south of the border, and then carried north by ocean currents to the waters off southern California.
Transboundary flows from Mexico into the United States occur regularly due to inadequate water infrastructure that becomes overwhelmed with wastewater, debris, and heavy precipitation. Ideally, wastewater from the City of Tijuana is supposed to be diverted before entering the Tijuana River Valley in California, treated, and discharged 5 miles south of the border into the Pacific Ocean. However, the water diversion infrastructure in Mexico and in the United States is frequently overwhelmed, especially during wet weather events causing untreated wastewater overflow to enter the Tijuana River Valley and Estuary and flow into the Pacific Ocean south of the city of Imperial Beach. These overflows of untreated wastewater, sewage, and debris impede public access to the coast as beaches are closed throughout the year due to poor water quality and fecal contamination. Communities in the region suffer from poor air quality caused by the aerosolization and stench of pollutants carried through the transboundary flows. Local, state, and federal actions are necessary to holistically solve this crisis. To learn more about the current activities and partnerships involved in addressing the Tijuana River Valley pollution crisis and the role of the California State Lands Commission, read below.
Tijuana River Valley: A Jurisdictional Overview
The Commission has jurisdiction over tide and submerged land located in and near the Tijuana River Watershed and the Pacific Ocean. The Commission manages these lands under the Public Trust Doctrine, a doctrine that mandates that California’s oceans, rivers, and lakes be used to benefit the statewide public and preserved for navigation, fishing, maritime commerce, ecological preservation, and public access and recreation. The transboundary pollution is directly interfering with both the Commission’s mission and the public’s rights to enjoy their waters.
The Commission leases land in the Tijuana River Estuary to the California Department of Parks and Recreation for the Border Field State Park and to the U.S. Fish and Wildlife Service for the Tijuana River National Estuarine Research Reserve. The transboundary pollution damages both lease areas, impeding their ecological and recreational purposes.
The Commission also has jurisdiction over the Pacific Ocean adjacent to Imperial Beach and other beaches that have been closed to the public due to contamination. One of the Commission’s primary responsibilities is protecting public access to the ocean. Local jurisdictions have had to make difficult decisions to close beaches due to excessive levels of bacteria and pollutants due to the pollution. This is a necessary measure to protect public health, but it is unacceptable that the community is unable to access clean and safe beaches and coastal waters
The City of San Diego and the USIBWC lease tide and submerged land from the Commission in the Pacific Ocean for an outfall associated with the South Bay International Wastewater Treatment Plant. This outfall is used by the USIBWC to discharge treated wastewater from the South Bay International Treatment Plant. Transboundary pollution is not intended to be discharged from this outfall; however, in cases of emergency where the plant exceeds its flow capacity, untreated flows may be released through the outfall.
Regulatory Agencies
The Tijuana River Watershed is regulated by various agencies. The International Boundary and Water Commission is a binational agency that oversees water treaties between the United States and Mexico, and is the federal entity charged with implementing international agreements that regulate water quality along the United States – Mexico border.
The USIBWC operates the South Bay International Wastewater Treatment Plant and other water quality infrastructure on the U.S. - side of the border intended to protect California’s water quality from transboundary pollution following through the Tijuana River.
The San Diego Regional Water Quality Control Board (San Diego Water Board) administers water quality laws, including the Clean Water Act. The San Diego Water Board regulates USIBWC water discharges under a National Pollutant Discharge Elimination System (NPDES) permit. The USIBWC has been out of compliance with its permit since 2021, but as of August, it anticipated reaching compliance by October 2024. The San Diego Water Board and its staff have been closely monitoring the USIBWC’s efforts.
The U.S. EPA has a border office focused on issues related to the Tijuana River Valley; and the City of Imperial Beach, County of San Diego, and the City of San Diego operate the valley’s treatment plant and do most of the monitoring associated with it.
Recent Commission Actions
Throughout this crisis, the Commission has vigorously advocated for a resolution. The Commission has commented on the environmental review of infrastructure projects, advocated and supported legislation to direct funding and resources toward addressing the crisis. In 2018, the Commission filed a lawsuit alongside those filed by the San Diego Water Board; the San Diego Unified Port District; the Cities of San Diego, Chula Vista, and Imperial Beach; and the Surfrider Foundation, over the pollution discharges from the USIBWC’s facilities. After the federal government announced additional funding for wastewater infrastructure through a Record of Decision for the United States-Mexico-Canada Agreement (discussed below), the parties reached a settlement with the USIBWC in April 2022. The settlement dismissed the lawsuits in exchange for the USIBWC improving its canyon collector network, supporting a main channel berm, improving its stakeholder communication, and taking other steps to address the pollution that flows across the border.
- Regional Leaders Announce Settlement in Tijuana River Valley Sewage Litigation April 12, 2022
- Commission implores the U.S. EPA to take immediate action to protect the Tijuana River Estuary and California beaches February 7, 2020
- State Lands Commission Adopts Resolution Urging Federal Action on Tijuana River Valley Pollution December 6, 2019
- Commission granted Intervenor status in Tijuana River litigation December 13, 2018
Federal Infrastructure and Action Updates
In 2020, Congress passed the United States-Mexico Canada Agreement Implementation Act, which appropriated $300 million to the U.S. EPA to address the much-needed infrastructure repairs. In response, the U.S. EPA and the International Boundary and Water Commission conducted an environmental review of infrastructure improvement projects and signed a Record of Decision for the proposed United States-Mexico-Canada Agreement (US-MCA) Mitigation of Contaminated Transboundary Flows Project in June 2023. This Decision identified core projects to implement to address and mitigate transboundary flows. These projects include expanding the South Bay International Wastewater Treatment Plant, managing Tijuana canyon flows to the International Wastewater Treatment Plant, implementing Tijuana sewer repairs, and building an Advanced Primary Treatment Plant.
Using funds appropriated under the US - MCA, the U.S. International Boundary and Water Commission has begun to implement a phased construction approach to expand the South Bay Plant, which would expand the capacity of the Plant to up to 50 million gallons per day. In August 2024, the U.S. International Boundary and Water Commission awarded a contract for the design and construction of the rehabilitation and expansion of the South Bay Plant. Total design and construction are expected to take up to five years, and the cost is estimated at around $600 million dollars. Currently, around $400 million has been appropriated towards the project.
Solving the current scale of transboundary flows requires a holistic approach of infrastructure improvement projects, as highlighted by the Record of Decision, which requires additional funding and environmental review.
For updates on the status of federal infrastructure, please visit:
- The International Boundary and Water Commission for updates on the status and progress of construction efforts to repair and expand the South Bay International Treatment Plant.
- USMCA Tijuana River Watershed for updates on actions and information related to the United States – Mexico- Canada Agreement.
State Projects and Updates
While the federal government has the exclusive authority to maintain and expand the infrastructure directly addressing transboundary flows, the State has funded projects to help address the impacts of infrastructure failures in federal facilities and in Mexico. In 2021, SB 170 funded three projects in the Tijuana River Valley through the State Water Resources Control Board Division of Financial Assistance. These include the Tijuana River Flood Control Trash Control Structure, the Smuggler’s Gulch Dredging Project, and the Tijuana River Valley Hydrology and Habitat Restoration.
The Tijuana River trash control structure project involves the design, construction, operation, and maintenance of a floating trash boom system for one storm season in the main channel of the river, immediately downstream of the international border. This demonstration project is in the process of obtaining environmental permits to begin installation, which is expected to be complete by early 2025.
The Smuggler’s Gulch dredging project will remove up to 30,000 cubic yards of accumulated sediment, trash, and debris in Smuggler’s Gulch and the Tijuana River Pilot Channel. This accumulation of sediment, trash, and debris contributes to flooding, threatening public and private properties and critical habitats. This dredging project is necessary before the installation of permanent sediment and trash capture infrastructure at Smuggler’s Gulch, which will be funded by a separate grant. The project will be completed by fall 2025.
The Tijuana River Valley hydrology and habitat restoration project will remediate a contaminated seven-acre property adjacent to the Tijuana River and restore it to native upland coastal sage scrub habitat. The County has completed the demolition of on-site structures, soil preparation, irrigation installation, and planting of vegetation. The project will be completed by fall 2025.
In addition to these three projects, the San Diego Water Board has developed a draft Advance Restoration Plan to address water quality impairments through an implementation plan with actions to restore and maintain water quality standards. San Diego Water Board staff will present the Advanced Restoration Plan to the San Diego Water Board to for adoption later this year.
For updates on the status of state projects, please visit:
- The San Diego Regional Water Quality Control Board for updates on the above-described state efforts to mitigate pollution flows.