Previous Article
Next Article

Your authoritative, multi-channel network for natural resources and environmental information since 1989 – by practioners for practitioners.

Line Spacing+- AFont Size+- Print This Article Back To Homepage

Cross-Border U.S.-Mexico Sewage Pollution Claim Makes Its Way to Federal Court

Cross-border pollution, which has plagued the region in and around the Tijuana River watershed in southern San Diego County since the 1930s, has been flaring up again, leading to a lawsuit by local agencies against the commission overseeing the capture and treatment of fugitive flows. [City of Imperial Beach, et al. v. International Boundary Commission, Case No. 3:18-cv-00457-JM-JMA (S.D. Cal. 2018).]

Transboundary flows, which can be comprised of treated and untreated wastewater, often carry substantial amounts of sediment, trash, and other pollutants. Human bacterial and viral pathogens have historically been detected in the surf zone of the Tijuana River during wet weather. Treatment of these flows, which are largely produced in Mexico, is further complicated by Tijuana’s challenging topography, with many canyons and hillsides, which drain toward the international border. When it rains, the existing infrastructure on the U.S. side is unable to stem the large volumes of polluted runoff flowing down the river channel. Even without rain, equipment failures or broken lines in Tijuana regularly lead to cross-border spills. Further, ocean currents carry pollutants and contaminants from the shoreline of the Tijuana River Valley upcoast to California beaches.

The City of San Diego has declared a continued state of emergency since September 1993 in connection with these discharges. In March 2017, the government of Baja California also declared an environmental state of emergency due to excessive volumes of raw sewage flowing from the Tijuana sewage collection system into waters in the city of Tijuana and the Tijuana River Valley.



The Tijuana River watershed is approximately 1,700-square miles and straddles the U.S.- Mexico international border. The watershed is a diverse and complex drainage system ranging from 6,000-foot high pine forest-covered mountains to the tidal saltwater estuary at the mouth of the Tijuana River. Nearly three-quarters of the watershed is located in Mexico, but the watershed drains to the Pacific Ocean in the U.S. through the eight-square-mile Tijuana River Valley, located adjacent to the border.

The Tijuana River Valley’s aquatic system consists of three general components: the river, the estuary, and the ocean shoreline. The Tijuana River Estuary, a marine-dominated estuary with habitats as diverse as sand dunes and beaches, vernal pools, tidal channels, mudflats, coastal sage scrub occupied by multiple endangered species, was established by the Coastal Zone Management Act and the California State Park and Recreation Commission as a Natural Reserve.

Issues related to the Tijuana River Valley’s aquatic system fall under the jurisdiction of the International Boundary and Water Commission (IBWC), an agency established by the U.S.-Mexico Convention of March 1, 1889, for the purpose of applying the rules in a 1884 Convention and resolving disputes over the international boundary line formed by the Rio Grande and the Colorado Rivers. In 1944, by treaty between the U.S. and Mexico (1944 Treaty) on the Utilization of Waters of the Colorado River and Tijuana Rivers and of the Rio Grande, the IBWC was authorized to exercise the rights and obligations of both governments under the Treaty and to give attention to the issue of border sanitation.

The IBWC consists of a U.S. Section (USIBWC) and a Mexican Section, Comisión Internacional de Límites y Agua (CILA), each with exclusive jurisdiction and control over matters and within the territorial limits of their respective countries.

Decisions of the IBWC are recorded in the form of “Minutes,” which become binding on the parties if not disapproved within 30 days.


Progress by the ‘Minute’

On September 24, 1979, the IBWC submitted Minute 261, which the U.S. and Mexico approved, whereby the IBWC agrees to “give permanent attention to border sanitation problems and give currently existing problems immediate and priority attention.”

In 1990, the IBWC entered into an international agreement, known as Minute 283, for the construction, operation, and maintenance of the South Bay International Wastewater Treatment Plant (SBIWTP). The SBIWTP’s purpose is to capture (within the facilities’ designed capacity), and treat to secondary standards Tijuana wastewater that would otherwise flow into the United States through the Tijuana River and its tributaries, for eventual discharge in the Pacific Ocean through the South Bay Ocean Outfall under a Clean Water Act National Pollutant Discharge Elimination System (NPDES) Permit. Minute 283 provided that Mexico had the primary responsibility for preventing the discharge of wastewater to receiving waters in the Tijuana River Valley, and the USIBWC had the role of assisting with equipment, maintenance and resources in the containment of wastewater discharges through utilization of collectors which collect and divert untreated sewage and other dry transboundary flows to the SBIWTP for treatment. Congress authorized the construction of the SBIWTP and appropriated necessary funds for its construction and operation. Minute 283 located the SBIWTP in the United States; it is owned and administered by the USIBWC and is operated and maintained by a private contractor, Veolia Water North America – West, LLC.

The San Diego Regional Water Quality Control Board (RWQCB) began regulating discharges of waste from the SBIWTP on November 14, 1996 by Order No. 96-50 and National Pollutant Discharge Elimination System Permit No. CA0108928. The San Diego RWQCB currently regulates the SBIWTP by Order No. 2014-0009 (2014 NPDES Permit).

In October 2015, the USIBWC and CILA signed Minute 320, which established a framework for addressing the solid waste, sediment, and water quality problems in the Tijuana River watershed. This resulted in the formation of a binational water quality working group as well as an executive-level binational core group (BCG).


A Persistent and Growing Problem

Rapid population growth within the watershed and unplanned housing developments, combined with aging infrastructure and treatment facilities are increasing the volume of uncontrolled transboundary flows, leading to frequent beach closures in Imperial Beach and other neighboring San Diego beaches.

Dry-weather flows in the Tijuana River, averaging around 14 million gallons per day are captured in Tijuana and diverted from the river’s main channel through a pump station operated by CILA and through other Mexico-side infrastructure. Under certain circumstances, such as when Tijuana’s sewer system fails or due to other problems with the river diversion infrastructure, uncollected flows reach the tributaries into the United States. Five of these tributaries contain canyon collector systems, which collect and divert the flows for treatment at the SBIWTP. However, the flows often exceed the SBIWTP treatment capacity.

During wet weather, the problem is exacerbated as the Tijuana River swells considerably. Stormwater can increase flow volume to over one billion gallons per day. After almost any rain event, flows in the Tijuana River exceed 27 million gallons per day, a level that surpasses CILA’s wastewater treatment capacity. Under those conditions, Mexico-side diversion infrastructure in the main channel of the Tijuana River are shut down, and water flows from Mexico into the United States through the Tijuana River, ultimately draining into the U.S. waters of the Pacific Ocean south of Imperial Beach. Depending on the amount and frequency of rainfall, it may be days, weeks, or months, before the Tijuana River’s flow falls below the 27 million gallons per day threshold at which the Mexico-side diversion infrastructure can resume operation.


The December 2017 Workshop and Ensuing Lawsuit

On September 27, 2017, following a significant cross-border raw sewage release a few months earlier in February, the City of Imperial Beach (Imperial Beach), the San Diego Unified Port District (Port District), and the City of Chula Vista notified the USIBWC and Veolia Water North America -West, LLC., of their intent to sue over Tijuana River Valley pollution discharges. On October 12, 2017, the San Diego RWQCB issued a tentative draft order (Order No. R9-2017-0135) requiring the IBWC to produce a water and sediment quality monitoring plan for the Tijuana River.

The result was a workshop meeting on December 12, 2017 (Workshop) between the Department of Justice, U.S. Environmental Protection Agency, Department of State, the USIBWC, and the cities of Imperial Beach, San Diego, National City, the County of San Diego, the San Diego Unified Port District, and the San Diego RWQCB. The Workshop resulted in a distilled list of priority projects; the cities and San Diego Regional Board also sought certain commitments from the USIBWC to address cross-border pollution. The projects included: 1) a main river channel pollution interception facility with a conveyance to the SBIWTP; 2) enhanced wastewater capture and control facilities in the hills west of the Tijuana River’s intersection with the international border, including a new collector/diversion in Yogurt Canyon; and 3) a functioning water quality monitoring and assessment program.

In a letter response to the State Water Resources Control Board dated March 1, 2018, the IBWC stated that, among other things, the USIBWC structure “does not contemplate the sort of unilateral commitments and decisions on infrastructure investments outlined by the Water Board,” that the USIBWC’s role under the 1944 Water Treaty does not make it the agency that, under U.S. law, is “responsible for managing transboundary trash, sewage, and sediment discharges” from Mexico, and that the USIBWC cannot commit to funding projects for which it has not received appropriations from Congress.

On March 2, 2018, Imperial Beach joined Chula Vista and the Port of San Diego in a federal lawsuit in the U.S. District Court for the Southern District of California against the USIBWC et al., alleging the USIBWC repeatedly failed to take measures to address pollution in the Tijuana River Valley under the Clean Water Act (CWA) and the Resource Conservation and Recovery Act (RCRA). Specifically, the lawsuit alleges violations of §§ 1311(a) and 1342 of the CWA, which prohibit the discharge of pollutants without NPDES permit or in violation of NPDES permit. The complaint also claims regarding the alleged violation of section 6972(a)(1)(B) of the RCRA (RCRA Citizen Suit provision), which authorizes any person to commence a civil action against a past or present owner or operator of a wastewater treatment facility who may have contributed or is now contributing to the handling, storage, treatment, transportation, or disposal of any solid or hazardous waste which may present an imminent and substantial endangerment to health or the environment.

In their prayer for relief, plaintiffs requested: 1) injunctive and equitable relief to compel defendants to comply with CWA and RCRA, including an order enjoining discharges of pollutants and solid and/or hazardous wastes; 2) civil penalties; 3) litigation costs and reasonable attorneys’ fees; (iv) prejudgment interest; and 4) any other and further relief as the court deems just, proper, and appropriate.


Conclusion and Implications

On August 13, 2018, the Department of Justice argued in court that the case must be dismissed on the ground that the USIBWC did not create the pollution, and therefore the federal agency and the civilian contractor that manages the SBIWTP are not responsible for the problem. The federal judge overseeing the case plans to visit the border to assess the situation before he issues a decision on the government request for dismissal. A decision on the Department of Justice motion could come relatively soon.

(Maya Mouawad, Steve Anderson)


Environmental, Energy and Climate Change Law & Regulation