International Boundary and Water Commission: Opportunities Exist to Address Water Quality Problems

Ongoing sewage spills and stormwater runoff carrying trash, sediment, and other pollutants in the Santa Cruz River Basin and Tijuana River Valley watersheds along the U.S.-Mexico border have affected public health, the environment, and local economies. Under the 1944 treaty, the United States and Mexico agreed to work together through IBWC to address these water quality problems. As part of this effort, USIBWC manages two wastewater treatment plants in Arizona and California. In 2018, the plants treated more than 14 billion gallons of sewage from Mexico.

This report (1) describes the authorities and roles for developing and managing the plants and sharing their costs; (2) examines factors affecting the operation of each plant and steps taken to address them; and (3) examines the extent to which USIBWC has taken actions to address water quality problems in the watersheds. GAO reviewed U.S-Mexico treaties, IBWC minutes and permits, and planning and budget data for USIBWC. GAO also interviewed officials from IBWC and other federal agencies, local and state governments, and non-governmental groups.

A 1944 treaty designated the International Boundary and Water Commission (IBWC) and authorized it to resolve water and boundary issues along the U.S.-Mexico border, including providing wastewater treatment. IBWC's two sections—the U.S. Section (USIBWC) and the Mexican Section, negotiated agreements to construct, manage, and operate two wastewater plants in Nogales, Arizona, and San Ysidro (South Bay), California, to resolve ongoing water quality problems stemming from sewage flowing downhill from Mexico into the United States (see figure). Several of these agreements describe each country's roles, such as sharing costs for the operation and maintenance of each plant.

Several factors can affect the plants' operations, including deteriorating infrastructure in Mexico and the United States that results in raw sewage spills around the plants. USIBWC has taken steps to resolve some of these factors. For example, USIBWC proposed a binational rapid response team to address broken pipes and failing pumps that can send sewage from Mexico into the United States; however, the team has not been formalized to ensure its long-term operation. By taking steps to formalize the team, USIBWC would have assurance it can more effectively address recurring infrastructure failures contributing to sewage spills.

USIBWC and others have taken some actions to address stormwater problems, such as studying stormwater flows in the Tijuana River Valley watershed and building some retention basins. However, USIBWC has not taken action, in coordination with federal, state, and local partners, to identify alternatives, cost estimates, funding sources, and time frames for implementing solutions in either watershed. USIBWC officials said without direction from Congress, it does not have specific authorization for stormwater management in the watersheds because the 1944 treaty and accompanying legislation did not authorize it to carry out such projects. The long-standing stormwater quality problems and their associated environmental and health effects suggest congressional direction is needed to authorize USIBWC to take action. Such action would include identifying alternatives, cost estimates, funding sources, and time frames.

GAO believes that Congress should consider providing direction and specific authorization to USIBWC to take action to resolve stormwater quality problems in the Santa Cruz River Basin and Tijuana River Valley watersheds. GAO is also making two recommendations to USIBWC, including that it formalize the rapid response team. USIBWC concurred with that recommendation and partly concurred with the other.

For almost 2 decades, we have reported on water quality problems in the  Santa Cruz River Basin and Tijuana River Valley watersheds along the  U.S.-Mexico border that have affected public health, the environment, and  local economies. In that time, the United States and Mexico negotiated  to jointly build two international wastewater treatment plants in southern  Arizona and southern California to treat sewage flowing from higher  terrain in Mexico downhill into the United States. However, wastewater  pipeline breaks in Mexico continue to send sewage across the border,  and stormwater from Mexico continues to carry trash from city streets,  sediment, and bacteria into the United States. Stormwater runs off paved  surfaces or other impervious areas into water bodies and may contain  pollutants that the water picks up as it runs over such surfaces. In the  Tijuana River Valley watershed, from 2003 through 2017, officials from  the City of Imperial Beach, California, closed public beaches for at least  one-quarter of the year and up to half the year in some years due to  sewage contamination, according to data from the city.

Through the binational International Boundary and Water Commission  (IBWC), the United States and Mexico have negotiated agreements to  address wastewater management problems along the border, including  agreements for the construction of the Nogales International Wastewater  Treatment Plant in the Santa Cruz River Basin watershed near Nogales,  Arizona, and the South Bay International Wastewater Treatment Plant in the Tijuana River Valley watershed near San Diego, California. The plants  are subject to the United States’ Clean Water Act, which prohibits the  discharge of pollutants from point sources into waters of the United States  without a permit from the Environmental Protection Agency (EPA) or an  authorized state. Specifically, the Clean Water Act regulates discharges  from wastewater treatment plants through the issuance of permits under  EPA’s National Pollutant Discharge Elimination System (NPDES)  program. These permits limit the amount of pollutants that can be  discharged. The Arizona and California state governments have issued  and administer NPDES permits for the Nogales plant and South Bay  plant, respectively.

IBWC was authorized to address water management issues along the  border by a 1944 treaty between the United States and Mexico, the  Treaty Relating to the Utilization of Waters of the Colorado and Tijuana  Rivers and of the Rio Grande, among other agreements. The  commission is comprised of a U.S. Section (known as USIBWC) and a  Mexican Section; these sections are administered independently of each  other. Under the 1944 treaty, the two sections may initiate and carry out  investigations to plan, construct, and operate works, such as international  water treatment plants, and recommend cost-sharing agreements  between the two countries.

To carry out their responsibilities under the 1944 treaty, USIBWC and the  Mexican Section negotiate legally binding agreements known as minutes,  which are subject to the approval of both governments. For example, after  negotiating minutes, the U.S. and Mexican governments agreed to share  the costs to build the two plants in the United States, and IBWC has cost- sharing agreements in place to pay for both plants’ operations. In  addition, USIBWC has a cost-sharing agreement with the City of Nogales  for the city’s use of the Nogales plant to treat its wastewater.

You requested that we examine the two international wastewater  treatment plants and their implementation of their NPDES permits. This  report (1) describes the authorities and roles involved in developing,  managing, and sharing costs for the two international wastewater plants  in the United States; (2) examines factors that affect the operation of the  two plants and steps IBWC has taken to address these factors; and (3)  examines the extent to which USIBWC has taken actions to address  water quality problems in the two watersheds, including through the use  of key capital planning principles.

To describe the authorities and roles involved in developing, managing,  and sharing the costs of the two international wastewater plants in the  United States, we reviewed the 1944 treaty and associated IBWC  minutes. We visited the Nogales and South Bay plants and interviewed  USIBWC officials. We also conducted interviews with officials at USIBWC  Headquarters in El Paso, Texas, and with the Mexican IBWC  Commissioner in Ciudad Juarez, Mexico. We interviewed other federal  officials at EPA, the Department of Homeland Security’s Customs and  Border Protection, and the Department of State during our site visits and  in Washington, D.C. We reviewed USIBWC’s budget, funding, data, and  costs associated with operating the Nogales and South Bay plants. To  determine if these data were reliable, we interviewed a USIBWC official  about the source of the data and any limitations to using it. We  determined the data are sufficiently reliable for reporting on the funding  used to pay for the plants.

To examine factors, if any, that affect the operation of the two plants and  steps IBWC has taken to address these factors, we reviewed each plant’s  NPDES permit and violation notices, and USIBWC documentation, such  as reports and plans for projects to resolve the violations. We also  interviewed USIBWC officials, as well as Arizona and California state  environmental officials responsible for developing and enforcing the  permits, to discuss permit violations and water quality problems at the  plants and actions USIBWC has taken to resolve them.

To examine the extent to which USIBWC has taken steps to address  water quality problems in the two watersheds, including using key capital  planning principles, we analyzed IBWC documentation including annual  financial reports and investment plans for each plant. We also interviewed  USIBWC officials and stakeholders at each plant, including local  government officials and environmental group representatives, about the  water quality problems and solutions. We compared USIBWC’s capital  planning efforts against the Office of Management and Budget’s (OMB)  Capital Programming Guide (Version 3.0) Supplement to OMB Circular  No. A-11, other OMB related guidance, and our reports on key capital  planning principles. (See app. I for further details of our scope and  methodology.)

We conducted this performance audit from September 2018 to January  2020 in accordance with generally accepted government auditing  standards. Those standards require that we plan and perform the audit to  obtain sufficient, appropriate evidence to provide a reasonable basis for  our findings and conclusions based on our audit objectives. We believe  that the evidence obtained provides a reasonable basis for our findings  and conclusions based on our audit objectives.

In the Santa Cruz River Basin and Tijuana River Valley watersheds,  which straddle portions of the 1,954-mile U.S.-Mexico border, water flows  north from higher elevations in Mexico into the United States. Both  countries have infrastructure along the border to manage, divert, and treat  wastewater, including sewers, pipelines, and treatment plants, in addition  to the two international wastewater treatment plants in the United States.  The Nogales and South Bay plants are located in the middle and lower  end of the Santa Cruz River Basin and Tijuana River Valley, respectively.  Figure 1 shows the location of the international wastewater treatment  plants along the border.

In 2018, USIBWC treated more than a combined 14 billion gallons of  sewage at the Nogales and South Bay international wastewater treatment  plants. At the Nogales plant, USIBWC treated 4.5 billion gallons of  sewage—an average of 12.45 million gallons per day from the city of  Nogales in Sonora, Mexico. In addition, the plant treats an average of 2  million to 2.5 million gallons per day of sewage from the Arizona cities of  Nogales and Rio Rico. The Nogales plant discharges treated wastewater  into the Santa Cruz River. At the South Bay plant, USIBWC treated 9  billion gallons of sewage in 2018—an average of 24.8 million gallons per  day from the City of Tijuana in Baja California, Mexico. The South Bay  plant discharges treated wastewater though a pipeline, called the South  Bay Ocean Outfall, into the Pacific Ocean.

Both watersheds are located in arid regions characterized by infrequent  but sometimes intense precipitation that forms short-lived streams or  washes that fill with water during such events but may be dry at other  times. These high-precipitation events lead to high levels of stormwater  runoff. Urban stormwater is a major contributor to pollution in the nation’s  waterbodies, including rivers and oceans, and can contribute to disease  outbreaks and beach closings, as well as flooding.

International Boundary and Water Commission

IBWC’s mission is to provide binational solutions to issues that arise  during the application of U.S.-Mexico treaties regarding, among other  things, water quality and flood control in the border region including  constructing and operating wastewater treatment plants, as directed by  Congress. The U.S. and Mexican governments established IBWC (then  the International Boundary Commission) in 1889, initially to resolve  boundary-related differences arising along the border. Various  agreements between the United States and Mexico added water  distribution and flood management in the transboundary rivers to IBWC’s  responsibilities, including management of the border reaches of the Rio  Grande and Colorado rivers. In the 1944 treaty, Utilization of Waters of  the Colorado and Tijuana Rivers and of the Rio Grande, the United  States and Mexico agreed to apportion their shared waters, distributing  the waters of the Colorado River and the Rio Grande between both  countries. As part of the 1944 treaty, the United States agreed to annually  provide a guaranteed amount of water from the Colorado River to  Mexico—unless deliveries were limited by extraordinary drought—and to  allocate the waters of the Rio Grande between the two countries, as well  as authorizing jointly built and operated dams, reservoirs, and  hydroelectric plants to manage water from the Rio Grande River.  USIBWC manages this infrastructure and ensures annual compliance  with the 1944 treaty water delivery requirements. As part of its flood control efforts, IBWC maintains and manages over 500 miles of levees for  flood protection.

The 1944 treaty established the key organizational components of IBWC  and its two sections—USIBWC and the Mexican Section—which are  federal agencies of their respective governments. Under the treaty,  USIBWC and the Mexican Section are each headed by a commissioner  who is an engineer. The treaty allows each commissioner to employ  engineers, legal advisers, and assistants as needed and established  certain positions—two principal engineers, legal counsel, and a secretary  (that is, a foreign officer)—as entitled to diplomatic status in the other  country’s territory. USIBWC is headquartered in El Paso, Texas, and the  Mexican Section is headquartered in the adjoining city of Ciudad Juarez,  Chihuahua, Mexico. USIBWC and the Mexican Section also have their  own field offices along the border that operate and oversee joint work.

U.S. Section of the International Boundary and Water Commission

USIBWC operates under the foreign policy guidance of the Department of  State and implements treaties between the United States and Mexico  related to boundary preservation and water management, including  border sanitation and flood control in the border region. USIBWC is  headed by the U.S. Commissioner and is made up of six executive offices  and three departments, with about 240 full-time equivalent employees as  of fiscal year 2017, the most recent data available at the time of our  review. The six offices include the Foreign Affairs Office and a Legal  Affairs Office; the former houses the foreign officer responsible for  diplomatic communications and provides advice for the interpretation of  treaties and minutes, and the latter houses legal counsel. The three  departments in USIBWC are the

Administrative Department, which supports all agency functions  through acquisitions, budget, finance, accounting, and information  management;

Engineering Department, which is headed by a Principal Engineer of  Engineering who provides technical and policy advice to the U.S.  Commissioner and technical support in planning, engineering,  environmental management, and construction management; and

Operations Department, which is headed by the Principal Engineer  of Operations who through the agency’s field offices oversees the  maintenance and operations of the two international wastewater  treatment plants as well as more than 100 hydrologic gaging stations,  500 miles of levees, four diversion dams, two international storage  dams and associated hydroelectric power plants, more than 600  hydraulic structures, and one-half of all international boundary  monuments and markers on the U.S.-Mexico land border and at  international ports of entry.

USIBWC’s annual budget, which has averaged $75 million per year since  fiscal year 2010, is submitted to Congress as part of the Department of  State’s overall budget. Under State’s budget process, USIBWC submits a  budget request 2 years in advance of the funding to be spent. Once the  department’s leadership approves USIBWC’s budget, it is incorporated  into the overall departmental budget request for review by OMB. After  OMB’s review, the budget is included as part of the President’s annual  budget request to Congress. The agency receives its appropriated  funding in two budget line items: (1) Salaries and Expenses and (2)  Construction.

As shown in figure 2, USIBWC funding has declined, when considering  inflation (fiscal year 2018 dollars). According to USIBWC officials, the  agency’s funding has increased about 1.1 percent per year since fiscal  year 2010 and has been relatively flat since fiscal year 2017. According to  a USIBWC budget official, the agency’s costs are increasing at an  average inflation rate of nearly 3 percent per year. USIBWC’s budget  from fiscal years 2010 through 2019, however, was more than double its  budget from fiscal years 2003 through 2007. According to the official,  starting in fiscal year 2010, the agency received an increase in its  construction appropriations to fund dam and levee improvements along  the border. Before that, in fiscal year 2008, USIBWC received additional  appropriations of $55.6 million to pay for levee repairs; and in fiscal year  2009, under the American Recovery and Restoration Act, received $220  million for construction projects.

Other Federal Agencies Involved with Water Infrastructure Projects on the U.S.-Mexico Border

In addition to USIBWC, other federal agencies that manage or collaborate  on water infrastructure projects in communities along the U.S.-Mexico  border include the following:  U.S. Army Corps of Engineers (Corps). The Corps provides assistance  for flood control, wastewater treatment, drinking water, and water supply  projects in communities across the United States, as directed by  Congress. To provide flood control assistance, the Corps’ Emergency  Streambank and Shoreline Protection program plans, designs, and  constructs erosion control projects that protect public infrastructure. It  conducts these directly or under contract with other federal agencies,  such as USIBWC. Congress has also authorized the Corps to provide  assistance to nonfederal interests for carrying out water-related  environmental infrastructure and resource protection and development  projects, including waste water treatment and related facilities. In  addition, the Corps’ Planning Assistance to States program helps states,  local governments, and tribes with preparing comprehensive plans for the  development and conservation of water and related land resources.

The Corps has worked on various projects along the U.S.-Mexico border.  For example, to address stormwater that flows downhill from Nogales,  Sonora into Nogales, Arizona, near USIBWC’s Nogales plant, USIBWC  requested an evaluation by the Corps on possible flood protection  improvements in Mexico, which was completed in 2004. Based on the  Corps’ recommendations, the local and federal governments in Mexico  constructed several dams and detention basins. To address flooding of  the Tijuana River in southern California, USIBWC contracted with the  Corps to implement the U.S. portion of the Tijuana Flood Control Project  in 1978. For this project, the Corps prepared construction plans and  supervised the construction of a quarter-mile concrete channel in the  United States that extends downstream from the U.S.-Mexico border.

EPA. In 1983, the United States and Mexico signed the Agreement on  Cooperation for the Protection and Improvement of the Environment in  the Border Area (the La Paz Agreement). In the agreement, the United  States and Mexico agreed to coordinate their efforts to address problems  of air, land, and water pollution in the border area, defined as the area  situated within 100 kilometers (approximately 62 miles) of either side of  the border. The agreement names EPA as the national coordinator  responsible for its implementation and provides EPA with a formal means  of working with its federal counterpart in Mexico on binational programs.  In addition, EPA and its Mexican counterpart created a binational  program to fund environmental improvement projects for communities along the border, called the U.S.-Mexico Border Water Infrastructure  Program. The most recent plan developed under the agreement—U.S.- Mexico Border 2020—is an 8-year cooperative program initiated in 2013  that identified five goals to protect the environment and public health in  both countries. The second goal—to improve access to clean and safe  water—includes protecting and restoring binational watersheds by  addressing the inadequate collection and treatment of wastewater. Under  the program, EPA works with federal agencies—including USIBWC—and  state and local agencies to build grant-funded projects to improve water  quality in the border area, including wastewater infrastructure projects  that connect to or are related to USIBWC’s two international wastewater  treatment plants in Arizona and California.

North American Development Bank (NADB). In 1993, another  agreement between the United States and Mexico led to the creation of  two entities—NADB and the Border Environmental Cooperation  Commission—to develop the environmental infrastructure of the U.S.- Mexico border region. NADB’s supervisory board includes  representatives from EPA and the Departments of State and Treasury.  NADB also established the Border Environment Infrastructure Fund to  administer grant funds provided by EPA, for the implementation of high- priority municipal water and wastewater infrastructure projects located  within 62 miles north of the U.S.-Mexico border, as well as 187 miles  south of the border. NADB funds wastewater and sewer projects in  communities along the border, including projects at USIBWC’s two  international wastewater treatment plants.

IBWC’s two wastewater treatment plants are required to meet water  quality standards under the Clean Water Act. The act establishes the  basic structure for regulating surface water quality, including regulation of  discharges of such pollutants as E. coli bacteria and heavy metals, such  as arsenic and lead, into the waters of the United States. The act requires  states to establish water quality standards that protect public health and  the environment and consider aquatic wildlife and human consumption  and recreation, among other uses. The act also requires EPA to maintain  and improve water quality by assisting and overseeing states’ efforts,  among other responsibilities. The states are required to monitor and  assess the conditions of water bodies, and those that do not meet state  water quality standards are considered impaired.

Other provisions of the Clean Water Act include the following:

NPDES permits. The Clean Water Act prohibits the discharge of  pollutants from point sources (sources of pollution, such as  wastewater treatment plants and industrial facilities) into waters of the  United States without a permit from EPA or an authorized state.  Under the act, EPA and authorized states issue NPDES permits for  point sources of pollution, which among other things regulate the  amount of pollutants that can be discharged. Another component of  the NPDES program is the pretreatment program, to prevent the  introduction of pollutants into a publicly owned wastewater treatment  plant that will interfere with its operation. According to EPA, by  reducing or eliminating waste from industries, fewer toxic pollutants  are discharged to and treated by the publicly owned wastewater  treatment plant, providing benefits to both these plants and the  industrial users. EPA has authorized most states, including Arizona  and California, to administer clean water discharge permits. The  Arizona Department of Environmental Quality administers the NPDES  permit for the Nogales plant. The plant is also subject to state permits,  such as an aquifer permit required in Arizona to limit the impact of the  plant’s discharge on groundwater in the vicinity. The San Diego  Regional Water Quality Control Board administers the NPDES permit  for the South Bay plant.

Stormwater runoff. Stormwater runoff is generated from rain and  snowmelt events that flow over land or impervious surfaces—such as  paved streets, parking lots, and building rooftops—and does not soak  into the ground. The NPDES stormwater program regulates some  stormwater discharges from three potential sources: certain municipal  storm sewer systems, construction activities, and industrial activities.  Operators of these sources might be required to obtain an NPDES  permit before they can discharge stormwater. This permitting  mechanism is designed to prevent stormwater runoff from washing  harmful pollutants into local surface waters.

Total Maximum Daily Load. Under the Clean Water Act, states must  establish water quality standards; for waters that do not meet these  standards, states must develop Total Maximum Daily Loads (TMDLs),  which EPA approves. TMDLs set targeted limits for pollutants but are  not self-implementing; EPA and states help reduce pollutants by  issuing permits for point sources, whereas they provide voluntary  incentives to reduce nonpoint source pollution (pollution that cannot  be traced to a single source).

Wastewater Utilities and Asset Management

Wastewater and stormwater utilities in the United States and Mexico are  managed, for the most part, by local municipal governments. In the  United States, local governments own and operate the majority of  drinking water and wastewater utilities and charge users for their service  through water rates. In Mexico, local and state governments, including  Nogales and Tijuana, own and operate drinking water and wastewater  utilities. Each city has its own sewer and wastewater infrastructure,  including wastewater treatment plants. For example, the state of Tijuana  Public Service Commission of Tijuana is responsible for the operation and  maintenance of wastewater collection and treatment infrastructure, and of  the drinking water distribution system. In the United States and Mexico,  stormwater may be managed by a wastewater utility or a local  municipality.

Asset management is a widely recognized tool used across a variety of  infrastructure sectors to manage physical assets, such as highways,  machinery, and buildings. In the case of water infrastructure, those assets  include pipelines, tanks, pumps, sewers, and other facilities. In a March  2004 report, we found that water utilities may benefit from implementing  asset management practices to better identify and manage their  infrastructure needs. To assist water utilities in adopting asset  management, in 2003, EPA developed an asset management framework  for water utilities. In 2008, EPA incorporated this framework into a best  practices guide for water utilities based on similar frameworks used by  water utilities in Australia and New Zealand. In a March 2004 report, we  reported that federal law does not require water utilities to use asset  management, but large water utilities may be more likely to use asset  management than small water utilities. In a January 2016 report, we  identified leading asset management practices for wastewater utilities that  include identifying key assets—such as pipelines, treatment plants, and  other facilities—and assessing their life-cycle costs.

We have also previously identified key capital planning principles that  apply to large capital acquisitions, such as infrastructure. For example, in  a February 2007 report, we identified five key planning principles in OMB  guidance on capital programming contained in OMB Circular A-11.  These include developing links between strategic goals and  infrastructure; developing a needs assessment and identifying gaps in  infrastructure; evaluating alternatives; using a review and approval  framework with criteria for selecting capital investments; and developing a  long-term capital investment plan. Further, OMB’s capital planning  guidance states that each capital asset should have an operations and  maintenance plan that outlines the procedures and responsibilities for  scheduled preventive and regular or routine corrective maintenance. In  addition, in November 2019, OMB issued a memorandum to federal  agencies that reinforced the need to implement the capital programming  guidance in OMB Circular A-11 that agencies develop, document, and  implement a capital planning process.

We have also previously found that economic guidance generally states  investment decisions such as those made for infrastructure should be  informed by a consideration of both benefits and costs of relevant  alternatives. For example, OMB has issued guidance on estimating  costs and benefits to help federal agencies efficiently allocate resources  through well-informed decision making about activities. This guidance  includes OMB Circular A-94, which we have previously identified as  providing leading practices for economic analysis. OMB Circular A-94  directs agencies to follow certain economic guidelines for estimating costs  and conducting cost-effectiveness analyses of federal programs or  policies to promote efficient resource allocation through well-informed  decision making in certain circumstances. The guidance applies to  federal agencies and programs, but we have previously found that it  provides leading practices for economic analysis of investment decisions.  Under OMB Circular A-94, a cost estimate is to include a comprehensive  assessment of the costs.

The Two Wastewater Plants Operate, and the United States and Mexico Manage and Share Costs, Under the 1944 Treaty

Under the 1944 Treaty, USIBWC and the Mexican Section have  negotiated minutes laying out the countries’ roles and responsibilities in  managing and operating the two wastewater treatment plants in the  United States. Under this authority, both sections have also established  cost-sharing agreements for the ongoing operation and maintenance of  each plant.

The 1944 Treaty and Related Minutes Establish IBWC in Its Current Form and Address the Construction, Management, and Operation of the Two Plants

The 1944 treaty establishes the jurisdiction, structure, and functions of  IBWC under the treaty, largely establishing IBWC’s present form and  processes. Specifically, IBWC is authorized to jointly study, investigate,  and develop solutions to transboundary problems related to water and the  international boundary. Under the treaty, when a new or anticipated  boundary or water problem is identified, USIBWC and the Mexican  Section are to discuss solutions and make recommendations to their  respective governments for its resolution before negotiating a formal  solution through a minute. The early detection and evaluation of the  problem, followed by the development of measures for resolution, are a  part of IBWC’s mission, according to USIBWC’s website. The proposal for  a new IBWC project may be initiated by one or both governments, or by  state or local authorities in either country through their respective IBWC  section. The project is then to be jointly investigated. If the findings of the  IBWC joint investigations show that a cooperative project is feasible and  is justified as a binational project, USIBWC and the Mexican Section may  endorse the findings in a minute and recommend the project to the United  States and Mexico governments.

Under the 1944 Treaty, IBWC is also authorized to resolve disputes  between the two countries arising from the interpretation or application of  the treaty. In ratifying the treaty, the U.S. Senate resolution specified that  USIBWC should only conduct work related to the eight projects identified  in the treaty and not undertake any other construction projects without  congressional authorization. As a result, USIBWC has received  separate authorizations from Congress for projects implemented through  treaty minutes, including the two international wastewater treatment  plants. Specifically, USIBWC constructed the Nogales and South Bay  plants under a series of statutory authorizations enacted in several  Congresses from the 1930s to the 2000s.

USIBWC officials said that IBWC can develop documents that are an  alternative to a minute but serve the purpose of gaining consensus  between the two sections. Alternatives include an exchange of letters, a  signed term of reference, and a joint report drafted by principal engineers  from USIBWC and the Mexican Section. A letter exchange would provide  the approval of an activity from both the U.S. and Mexican  Commissioners, such as flood operations criteria in any given year or  emergency notification protocols for communities along the border. A  term of reference would provide the scope of work for a project or  protocol, describe the work that the two sections will do, and how they will  do it. A joint report of the principal engineers is a technical document that  can describe ongoing activities or that can commit IBWC to a new activity.  These reports can be adopted as a minute, or, if the activity is already  under way, not adopted.

As a diplomatic agency under the Department of State, USIBWC can  negotiate agreements with Mexico on its own, but State gets involved in  certain situations, such as the negotiation and conclusion of an IBWC  minute, or with respect to large and costly projects, according to State  officials. For example, under the Department of State’s Circular 175  procedure, authorization to negotiate and conclude binding international  agreements is obtained via approval of a memorandum by the Secretary  of State or another Department of State senior official. The Department of  State may also provide diplomatic support in a variety of ways. For  example, State may draw attention to an issue by sending a diplomatic  note to the Mexican Embassy to formally request the need for action to  resolve a problem. Further, in coordination with USIBWC, the U.S.  Embassy and Consulates may engage with Mexican government officials  to advocate actions to address problems, such as water quality problems,  including during meetings with Mexican federal and local officials,  according to State officials.

The IBWC commissioners and staff from both USIBWC and the Mexican  Section work together in formal and informal ways, according to officials  from both sections. The commissioners meet on a regular basis to  discuss ongoing and, if appropriate, new, projects to carry out the treaty.  Between meetings, the commissioners exchange information through  formal channels with letters. In addition, according to USIBWC officials,  the two sections’ staff are in frequent contact, through formal and informal  communication. For example, USIBWC officials said staff from both  sections will exchange daily emails and telephone calls to discuss  information and collaboration on various IBWC projects.

Under Article 3 of the treaty, the joint use of international waters “is  subject to any sanitary measures or works which may be mutually agreed  upon by the two Governments, which hereby agree to give preferential  attention to the solution of all border sanitation problems.” Under this  article and the articles authorizing joint investigations and solutions, IBWC  has negotiated a series of minutes related to sanitation issues, one of  which dealt with the issue broadly and others of which dealt with specific  geographic locations. Each minute is pursuant to various statutory  authorizations in the United States. In 1979, IBWC signed Minute 261,  which provides that that the two countries should take timely measures to  prevent any border sanitation problem. The minute also provides that for  each border sanitation problem, IBWC would prepare a minute that would  identify the problem, the course of action for resolution, and a specific  time schedule for implementation.

Other minutes were executed for sanitation issues in Nogales and  Tijuana, pursuant to various statutory authorizations in the United States.  For the Nogales plant, Minute 206, signed in 1958, approved a jointly  operated and maintained wastewater plant in Arizona based on a Joint  Report by the principal engineers. Minute 227, signed in 1967, provided  for the relocation of the plant to its current location and expanded the  treatment capacity of the plant. Minute 276, signed in 1988, approved a  further increase in the capacity of the plant. For the South Bay plant,  Minute 283, signed in 1990, approved the construction of the South Bay  plant in San Ysidro, California. This minute described the water quality  situation, discussed alternatives to fix the problem, and recommended a  plan to fix it. The recommended plan included the building of the  international wastewater treatment plant, as well as completion of  Mexico’s sewage system for Tijuana, and other steps.

Construction and Operations of the Nogales International Wastewater

The Nogales plant provides secondary treatment for wastewater  generated in both Nogales, Arizona, and Nogales, Sonora, Mexico.  USIBWC and the City of Nogales, Arizona, own the plant, which began  operating in 1972.

In 1945, IBWC recommended that a plant be built 1.5-miles north of the  border with a treatment capacity of 1.6 million gallons per day. The plant   was completed in 1951. An underground pipeline, referred to as the  “trunkline,” was also constructed to transport the sewage under the  border from Mexico 1.5-miles to the plant for treatment. As the population  grew in both cities, the communities recognized the need for a larger  plant. At the request of the City of Nogales, Arizona, the new plant—with  a treatment capacity of 8.2 million gallons per day according to USIBWC  documents—was constructed 9-miles north of the border, at the  confluence of the Nogales Wash with the Santa Cruz River (see fig. 3).  Construction on the new plant began in 1970 and was completed in 1972.  In 1988, IBWC signed a minute upgrading the plant, adding additional  treatment capacity for Mexican wastewater. Then to comply with more  stringent federal and state regulations, the plant was upgraded in 1992  and 2009. At present, USIBWC manages the plant, which has treatment  capacity for up to 17.2 million gallons of wastewater from Mexico and the  United States per day according to USIBWC documents.

Wastewater treatment plants collect sewage  from residences and businesses and treat it to  remove pollutants such as sediment, bacteria,  and other materials. There are three types of  treatment at wastewater treatment plants in  the United States. States are required to meet  standards for two of them.   Primary treatment involves physical  processes such as screening and  sedimentation to remove a portion of  pollutants that settle or float.  Secondary treatment augments physical  treatment with biological processes to remove  organic matter. The treatment involves the  use of bacteria to consume waste material.  Secondary treatment, combined with  disinfecting chemicals, such as chlorine, can  reduce about 85 percent of pollutants.  Tertiary treatment involves specialized or  advanced treatment that is specific to the  pollutant. For example, some treatment plants  try to reduce nutrients such as nitrogen and  phosphorus. Tertiary treatment can include  additional filtration, reverse osmosis, or  additional chemical or biological processes.

The South Bay plant provides secondary treatment for wastewater  generated in Tijuana, Mexico. USIBWC operates the plant. In the  decades, before the plant was built in 1997, untreated sewage reached  the Tijuana River, which flows north from Mexico to San Diego,  California. The river transported raw sewage to the Pacific coast at  Imperial Beach, California, creating a nuisance and public health risk in  the United States. To address the problem, IBWC signed Minute 283 in  1990, which provided the framework for a project to treat wastewater from  Tijuana, Mexico, at a plant located in the United States. Construction  began in 1994. In 1997, the South Bay plant opened with discharge  through an emergency connection to the City of San Diego’s wastewater  treatment facility. The South Bay plant became fully operational in 1999,  providing advanced primary treatment for 25 million gallons of sewage  coming from Mexico daily and discharging treated wastewater 3-miles  offshore in the Pacific Ocean through the South Bay Ocean Outfall, which  is a 3.5-mile-long pipe, according to USIBWC documents.

The plant was upgraded with secondary treatment facilities in 2010. It is  designed to treat up to 25 million gallons per day of Tijuana’s sewage,  with the ability to treat up to 50 million gallons per day for a short period of  time, according to USIBWC officials. The City of Tijuana also operates  five wastewater treatment plants in Mexico to treat its remaining sewage,  though these plants are not always fully operational. The South Bay  plant’s facilities include five canyon collectors located along the border in  five of the six cross-border canyons. During normal operations, smaller  amounts or “low-flows” of urban runoff and wastewater from Mexico are  diverted by these canyon collectors and conveyed to the plant through  underground pipelines (see fig. 5).

IBWC Minutes Describe Roles, Responsibilities, Costs, and Cost-Sharing Agreements for Operating and Maintaining the Plant

IBWC minutes, with the approval of the U.S. and Mexican governments,  establish each country’s roles and responsibilities, outline the costs of the  Nogales and South Bay plants, and describe the cost-sharing  arrangements between the United States and Mexico for operating and  maintaining the plants. Minutes for each plant specify the cost-sharing  arrangement for construction. See appendix II for details of the IBWC  minutes that authorize the construction, management, and operation of  the two plants.

For the original Nogales plant, the U.S. government authorized the  funding in the Department of State, Justice, Commerce, and the Judiciary  Appropriation Act for 1947 and provided funding with certain conditions,  including that the City of Nogales agreed to furnish the lands or  easements free of cost and that the city operate and maintain the project  once it was completed.

Under Minute 227, signed in 1967, Mexico agreed to participate in  funding the expansion of the capacity of facilities at the Nogales plant.  This Minute also authorized the relocation of the plant; however, the  Minute provided that Mexico’s share of the construction costs of enlarging  the international sewage treatment facilities would not change if the  United States for domestic reasons constructed the enlarged treatment  plant north of its existing site. Mexico conditioned its approval of the  relocation on the agreement that Mexico not bear any costs associated  with the extension of the IOI pipeline necessary for the relocation,  according to USIBWC officials. Further, under Minute 227, the United  States, Mexico, and the City of Nogales, Arizona, shared the construction  costs of the treatment plant. During the relocation of the plant and  resulting extension of the IOI, the City of Nogales acquired all easements  in land or the land necessary for the relocation and contributed $791,000  for the expanded plant and IOI, according to USIBWC officials. Mexico’s  share was based on the costs of enlarging the treatment plant at the site  used for the initial 1951 plant. Since the City of Nogales, Arizona, wanted  the plant to be located away from the city limits, the additional IOI costs  were not borne by Mexico.

The second plant was upgraded in 1988, 1992, and 2009. In 1988,  Mexico provided $1 million to pay for the additional capacity built at the  plant, as the total capacity allotted to Mexico after the upgrade was 9.9  million gallons per day, and the City of Nogales, Arizona, was allotted a  total capacity of 4.84 million gallons per day. The United States and the  City of Nogales, Arizona, shared the costs for the 2009 upgrade to the  facility. During the 2009 upgrade, EPA provided a $65 million grant to the  City of Nogales, Arizona; the City of Nogales, Arizona, contributed  $700,000; and USIBWC provided an additional $2 million for the  construction of an ultraviolet disinfection system according to USIBWC  documents.

For the South Bay plant, the United States and Mexico agreed to  construct the plant under Minute 283 and to share the costs for  construction, operation, and maintenance for the plant under Minute 296.  Congress authorized USIBWC’s participation in 1987 amendments to the  Clean Water Act. The construction cost for the plant was $241.1 million.  The United States contributed $224.6 million—specifically, EPA provided  $127.4 million to USIBWC for costs associated with the construction of  the plant and related infrastructure, $89.2 million to the City of San Diego  and the Corps to construct the South Bay Ocean Outfall, and $8 million to  the Corps for additional environmental work. Mexico contributed $16.8  million, which was the amount that it would have had to pay to construct  and maintain a plant in Mexico. As part of Minute 283, IBWC also built a  diversion infrastructure just south of the border to capture low-volume,  dry-weather flows in the Tijuana River to prevent northbound  transboundary flows into the United States. This diversion system is  operated by Mexican entities and includes pumps and pipelines that send  wastewater to the South Bay plant.

Minutes also specify cost-sharing arrangements for the ongoing operation  and maintenance of the plants. Under the cost-sharing agreements in  relevant minutes, the Mexican government generally reimburses USIBWC  annually for a portion of the treatment costs at each plant. The  reimbursement rate is annually adjusted based on what it would cost to  treat a similar amount of wastewater in Mexico according to USIBWC  officials. In addition, USIBWC has a separate agreement with the City of  Nogales, Arizona, for the Nogales plant that stipulates reimbursements  for their sewage treatment. These minutes and cost-sharing  arrangements are as follows:

Cost-Sharing Agreements for the Nogales plant. Under Minute  206, Mexico agreed to pay for some operations and maintenance  costs, based on its proportion of wastewater flows to the Nogales  plant for treatment, at a discounted rate for a predetermined amount  of sewage. IBWC commissioners periodically review this discounted  rate. Specifically, USIBWC assesses the percentage of sewage (up to  9.9 million gallons per day) Mexico sends to the Nogales plant and  adjusts the rate to what it would cost to perform the same service in  Mexico, according to USIBWC officials. Furthermore, the Mexican  government has agreed to pay full U.S. cost for any flow above the  treaty-allotted 9.9 million gallons per day, according to these officials.  Meters located at three sites along the U.S-Mexico border  continuously measure the sewage flow, and if the amount of sewage  treated by the plant exceeds the 9.9 million gallons per day, Mexico is  billed by USIBWC for the full cost of sewage treatment, according to  USIBWC officials. Separately, USIBWC charges a rate for treatment  of the city’s sewage under a Memorandum of Agreement with the City  of Nogales, Arizona.

Cost-Sharing Agreements for the South Bay plant. Under Minute  296, Mexico agreed to pay for operations and maintenance costs for  the plant based on the treatment of up to 25 million gallons per day.  The pump that diverts Tijuana’s wastewater into the South Bay plant  can pump as much as 29 million gallons per day, and the plant can  treat more than 25 million gallons per day if needed. Similar to the  Nogales plant, USIBWC, on a quarterly basis, bills the Mexican  government a prorated amount for the treatment services based on  the amount of flow. For example, in fiscal year 2018 Mexico paid  USIBWC about $2.4 million for treatment of its wastewater.

In fiscal year 2018, the plants’ operational and maintenance costs totaled  $4.5 million for the Nogales plant and $15 million for the South Bay plant,  and in that fiscal year, the Mexican government reimbursed USIBWC  $4.4 million for both plants, according to USIBWC documents. In addition,  according to USIBWC officials, the City of Nogales, Arizona is behind in  its payments for the Nogales plant by $3 million, and Mexico owes $3  million, according to officials. USIBWC initially pays for the operations and  maintenance costs at all its facilities, including the two wastewater  treatment plants, and then seeks reimbursement from Mexico and the  City of Nogales, Arizona, for their portions of the operation and  maintenance costs. The operation and maintenance costs for each plant  include the plant’s employees, such as water operators and skilled  technical employees, who manage nonstop operations such as running  the equipment, controlling the processes, and monitoring the facilities.  The Nogales plant employed 17 people as of 2019. USIBWC has used a  third-party contractor (Veolia Water Operating Services) to conduct  operational and maintenance activities at the South Bay plant since 1998,  according to officials. USIBWC Salaries and Expenses budget line item  includes funding for each plant’s operation and maintenance.

According to federal officials in the United States and Mexico, the  operations and maintenance of wastewater infrastructure in Mexico is an  ongoing challenge. According to these officials, Mexican wastewater  utilities do not have the resources or the long-term technical expertise to  address equipment maintenance problems in a timely manner to prevent  spills. Although NADB has provided financing to wastewater infrastructure  utilities that send wastewater to USIBWC’s Nogales and South Bay  plants, utilities often the lack the resources necessary to adequately  maintain the infrastructure and equipment after the construction loan  ends, according to NADB officials. NADB could condition financing for  every wastewater infrastructure project on capacity to adequately manage  operations and maintenance of the infrastructure, as it has for a few  projects, according to USIBWC and EPA officials. In the United States, as  we reported in January 2016 the U.S. Department of Agriculture includes  as one of its loan conditions the capacity of the wastewater utility to pay  for operations and maintenance of infrastructure.

USIBWC has identified numerous projects related to operating the plants  or building new infrastructure that remain unfunded under the agency’s  current appropriations level, according to an agency document.  USIBWC’s Budget Office, as part of its Fiscal Year Year-end Budget  Procedures and Guidance, annually sends its staff a report with the  projected balances for the Salaries and Expenses and Construction line  items for the remainder of that fiscal year. The guidance directs that each  department—Engineering, Operations, and Administration—identify work  or projects for which they need funding. Each projected balance is to be  calculated by subtracting expenses from each group’s allocated funding  for the year. The departments are to identify any outstanding  requirements and associated costs for the remainder of the fiscal year.  For fiscal year 2018, USIBWC identified $9 million in potential operations  and maintenance work and $2.8 million for potential construction projects,  based on agency documents. For example, USIBWC identified the need  for $149,000 for new pumps and motors for pump stations at the South  Bay plant but deferred the purchase due to other funding needs,  according to an official.

Several Factors Can Affect the Plants’ Operations, and Raw Sewage Periodically Spills into the Watersheds

Several factors can affect each plant’s operations. IBWC and others have  taken some actions to address the factors affecting each plant’s  operation, including initiating an informal binational rapid response team  to address breaking and failing wastewater infrastructure along the  border. However, IBWC has not taken the necessary steps to formalize  this rapid response team, and raw sewage continues to periodically spill  into the Santa Cruz River Basin and Tijuana River Valley watersheds.

Both Plants Operate Under Clean Water Act Permits and Several Factors Can Affect the Plants’ Operations

USIBWC’s Nogales and South Bay plants are subject to NPDES permits  issued by the states of Arizona and California, respectively, which  generally prohibit the discharge of pollutants from the plants unless  specifically allowed under the permit. Generally, a NPDES permit is  issued for a term of 5 years to a single facility and reflects site-specific  conditions of that facility.

The Nogales plant’s NPDES permit requirements are based on a  maximum monthly average of 17.2 million gallons per day to be treated  and discharged into the Santa Cruz River. The permit allows the  discharge of certain pollutants within specified limits, including some  heavy metals, such as mercury and copper. Under the permit, USIBWC  must also meet several monitoring requirements, including monitoring the  pollutants in the water coming into the plant from the IOI, the amount of  treated wastewater discharged into the Santa Cruz River, and the  presence of pollutants named in the permit. USIBWC is to submit this  information to Arizona Department of Environmental Quality (ADEQ) for  monthly or annual review. The Nogales plant permit also requires  USIBWC to remove sludge produced as part of the treatment process  and dispose of it at an offsite location that is certified to receive that type  of byproduct.

Since 2014, ADEQ has issued four Notices of Violation to USIBWC for  the Nogales plant’s permit. The notices cited the exceedances of certain  substances above permit limits, including some heavy metals in the  discharge (in 2019); the presence of pollutants toxic to human, animals,  plants, or other organisms (in 2018); untreated sewage spilled into a  tributary of the Santa Cruz River (in 2017); and USIBWC’s failure to  accurately monitor and report specific substances to ADEQ as outlined in  the permit (in 2014). Each notice outlined actions that USIBWC was  required to take to improve the water quality problem identified within a  specific time frame.

The South Bay plant has not received any Notices of Violation under its  current NPDES permit, which was issued in 2014, according to USIBWC  officials. The current permit covers the South Bay plant and other  infrastructure including five canyon collectors and the South Bay Ocean  Outfall. The permit sets a discharge limit of 25 million gallons per day of  treated wastewater, on a monthly average, to the Pacific Ocean through  the South Bay Ocean Outfall. The permit limits the pollutants that can  be discharged, such as zinc and mercury. Under the permit, USIBWC and  the City of San Diego conduct a joint monitoring program of the  wastewater discharge at the South Bay Ocean Outfall and are required to  submit the data collected from this joint monitoring effort to the San Diego  Water Board. The permit also includes monitoring requirements for  other parameters, including heavy metals and organic chemicals that are  considered harmful to the environment and public health. The South Bay  plant has not violated the permit’s discharge limits through the South Bay  Ocean Outfall since secondary treatment began in 2010, according to  USIBWC officials.

During rainstorms or wet weather in Tijuana and when pipelines or pumps  break, the plant does not treat all the water flowing from Mexico. During  these events, water flows to the Tijuana River and canyons and mixes  with unknown amounts of urban runoff, treated effluent from the Tijuana  River, and wastewater in Mexico and then flows into the Tijuana River  Valley watershed in the United States. During dry weather, the runoff is  largely groundwater and some untreated discharge from illegal  connections (dry-weather flows); during storms, this runoff mixes with  large amounts of rainfall (wet-weather flows).

There are several factors that can affect the operation of the Nogales  plant.

Lack of heavy metal pretreatment in Mexico. In Mexico, metal  treatment and plating facilities operate in Nogales, Sonora and directly  discharge wastewater that contains heavy metals into the city’s sewer  systems, which end up at the Nogales plant for treatment. While a  municipal pretreatment program exists in Nogales, Sonora, it is  designed to meet Mexico’s minimum federal requirements and is  insufficient to detect and respond to the dumping of industrial  contaminants when they occur, according to ADEQ documentation  and officials.

Deteriorating sewage infrastructure in Mexico. Sewage  infrastructure in the City of Nogales, Sonora, is not adequately  maintained, according to USIBWC officials. As a result, the city of  Nogales, Sonora, sends wastewater amounts to the plant in excess of  the amount agreed upon in the minute between USIBWC and the  Mexican section.

Due to the proximity of the plants to the U.S.- Mexico border, USIBWC’s international  wastewater treatment plants in southern  California and southern Arizona are located in  areas patrolled by Customs and Border  Protection (CBP) agents. In southern  California, the waterways in which sewage  pipelines connect to the South Bay  International Wastewater Treatment Plant  provide a natural crossing point at the border,  which CBP has blocked with gates.  In southern Arizona, drug smugglers use the  International Outfall Interceptor pipeline— which transports sewage from Mexico to the  Nogales International Wastewater Treatment  Plant—to transport drugs. According to CBP  officials, smugglers in Mexico drop drug  bundles into manholes that connect to the  pipe, and smugglers in the United States cut  into the pipe to retrieve the bundles. These  holes in the pipe can cause sanitary sewer  spills in Nogales, Arizona. CBP agents patrol  along the pipeline to catch smugglers and  retrieve the drug bundles, according to CBP  officials.

Deteriorating infrastructure in the United States. In the United  States, the deteriorating condition of the IOI causes untreated sewage  to periodically spill into the Santa Cruz River watershed and Nogales  Wash. The deterioration is due to the age of the pipe, as well as  ongoing corrosion and erosion of the pipeline (see fig. 6).

See appendix III for more details on the factors that affect the operations  of the Nogales plant.

One key factor affects the operation of the South Bay plant: insufficient  sewage infrastructure in Mexico contributes to transboundary sewage  flows that, if not diverted, can reach the plant and disrupt its operations.  According to a 2019 study, Tijuana has not built sufficient sewage  infrastructure to serve the area’s exponential population growth and  urbanization. When problems arise with Tijuana’s treatment facilities,  the city diverts a portion of its wastewater for treatment at the South Bay  plant. In these instances, the Mexican utility may also shut down Pump  Station CILA, a main pump located in the Tijuana River that diverts the  river to the treatment plant. If the South Bay plant is not notified and does  not shut down its pump and canyon collectors, it may receive additional  flows. While the plant can treat additional wastewater and has not  violated its NPDES permit, the plant is experiencing an increase in the  number of days that it treats above capacity, according to USIBWC  officials.

In addition, USIBWC officials stated that the South Bay plant is not  designed and operated to address some of the wastewater that flows into  the Tijuana River Valley watershed. These wastewater flows are due to:

Limited Tijuana Basin diversion infrastructure. The Tijuana Basin  diversion system consists of the Mexican-operated Pump Station  CILA and the South Bay plant’s canyon collectors. This system  captures dry-weather flows for treatment at the South Bay plant or for  a wastewater treatment plant in Mexico. However, it is not designed to  capture high flows that result from pipe breaks or pump failures. To  avoid affecting the South Bay plant’s wastewater treatment  operations, during incidents of high flows, Pump Station CILA and the  five canyon collectors are shut off. During these events, the water  bypasses the South Bay wastewater treatment plant and flows  untreated into the Tijuana River and watershed. For example, a  February 2017 spill from a broken pipeline in Mexico released 143  million gallons of sewage-contaminated water into the Tijuana River  that bypassed the South Bay plant and was not treated.

Lack of maintenance for existing sewage infrastructure in  Mexico. A lack of maintenance for Tijuana’s existing sewage  infrastructure causes excess wastewater flows into the Tijuana River  according to USIBWC officials. For example, in August 2019,  USIBWC reported that on June 19, 2019, 1.9 million gallons of  wastewater were released into the Tijuana River because of trash  buildup at one of Tijuana’s pumps that caused the pump to fail. A  2019 study also reported that the poor condition of critical wastewater  infrastructure in Mexico results in approximately 30 percent of  Tijuana’s wastewater entering the Tijuana River or Pacific Ocean  without treatment.

See appendix III for more details on these factors that affect the  operations of the South Bay plant.

IBWC and Others Have Taken Some Actions to Address the Factors that Affect the Plants’ Operations, but Releases of Raw Sewage Continue

USIBWC and the Mexican Section have taken some actions to address  the factors that can impede plant operations. However, raw sewage is still  released from Mexico into the Santa Cruz River Basin and Tijuana River  Valley watersheds and continues to have significant public health and  environmental impacts.

USIBWC and others have taken various actions to address the factors  that affect Nogales plant operations, including the following:

Sending letters to heavy metal dischargers. To address the  presence of heavy metals in the wastewater stream, in October 2018,  USIBWC, ADEQ, and EPA sent joint letters to four American  companies affiliated with the metal treatment and plating facilities in  Nogales, Sonora, Mexico. The letters asked for the companies’  cooperation in addressing the issue and offered to meet with each  company to discuss possible solutions. According to USIBWC  officials, they received a response from one company, but not the  other three. However, in continued monitoring, USIBWC has seen  fewer instances of heavy metals in the wastewater that it treats at the  Nogales plant according to agency officials.

Maintaining treatment capacity in Nogales, Sonora. To address  the inadequate wastewater infrastructure in Nogales, Sonora, IBWC  has collaborated with other stakeholders to maintain wastewater  treatment capacity in Mexico. For example, the U.S. State Department  sent a diplomatic note to the Mexican government in February 2019  regarding the failing pumps and asked the Mexican government to  quickly respond and eliminate the discharges that end up at the  Nogales plant. USIBWC officials stated that the Mexican Section of  the IBWC purchased two new pumps, which were expected to arrive  at the pump station in Nogales, Sonora, in late 2019. The Mexican  Section also plans to work with the local utility to install equipment to  remove grit from the wastewater and prevent degradation of the new  pumps.

Upgrading infrastructure in the United States. In 2005, USIBWC  proposed a five-phase plan to rehabilitate the IOI’s pipe that uses a  process referred to as “cured-in-place pipe.” In this process, a  polyester tube is inserted into the pipe and inflated, which then  hardens to become a pipe within a pipe. This process has an  estimated cost of $50 million. As of November 2019, the rehabilitation  had not started due to funding disagreements between USIBWC and  the state of Arizona. According to USIBWC officials, the agency does  not want to fund the entire project but has secured $28.1 million for it.

According to USIBWC officials, the City of Nogales will not contribute  any funding without a change to the current cost-sharing agreement  on reimbursements between the city and USIBWC for sewage  treatment. The cured-in-place pipe process will address some of the  IOI’s deferred maintenance issues but will not resolve ongoing  disagreements about which entity is responsible for funding annual  maintenance and operations. According to USIBWC officials, the  annual maintenance needs include more than the work to repair the  IOI. For example, lateral pipelines that connect City of Nogales  sewers to the IOI also need to be maintained; occasional breaches in  the pipeline need to be repaired; and vegetation management along  the pipeline is necessary to prevent root intrusion into the pipeline.  USIBWC officials estimated the annual cost for operations and  maintenance, including infrastructure repair and personnel costs, at  about $1.5 million to $2 million.

IBWC and others have also taken actions to address the pump failures  and pipeline breaks in Tijuana that send polluted flows downstream,  affecting the Tijuana Basin diversion infrastructure and subsequently the  South Bay plant. These actions include the following:

Negotiating a Binational Tijuana River Spill Notification Protocol.

In August 2017, IBWC negotiated a notification protocol for raw  sewage discharges into the Tijuana River that may enter the United  States. The protocol was prompted by the February 2017 spill from a  broken pipeline in Mexico of 143 million gallons of sewage- contaminated water that flowed into the Tijuana River. The initial  protocol stated that a formal memorandum of understanding would be  developed at a later date to formalize the protocol; however, the initial  protocol remains in place. According to an USIBWC official, Mexico  has since adhered to the protocol twice by warning USIBWC of  imminent raw sewage flows when pipelines in Tijuana, Mexico,  ruptured. However, in August 2019, USIBWC reported that most of  the transboundary flows were detected by an automated alert system  on the U.S. side of the border that was deployed by USIBWC in  October 2018 to better monitor and detect any transboundary flows.  The system relies on river gage data recorded at the Tijuana River  that is also posted to the USIBWC website.

Upgrading infrastructure in Mexico. In April 2018, the Department  of State sent a diplomatic note to the Mexican government after  failures in Tijuana’s sanitation infrastructure led to sewage flows on  multiple days in 2017 and 2018. The diplomatic note requested that  the Mexican government take appropriate measures (as outlined in  Minute 283) to stop sewage flows from crossing into the United  States, including making short-term repairs and longer-term upgrades.  According to USIBWC officials, Mexico does not have much funding  for its infrastructure. However, in March 2019, Mexico and EPA,  through NADB, funded the replacement of three segments of the  Poniente Collector in Tijuana, Mexico, to eliminate a key source of  untreated discharges into the Tijuana River in the United States.

Participating in the Tijuana River Diversion Study. In 2019, NADB  funded the study of alternatives to expand or adapt the diversion  infrastructure in the Tijuana River to identify potential infrastructure  projects (and associated costs) to divert dry-weather flows and  possibly some flows that result from wet weather mixed with  wastewater and raw sewage. The study developed project  alternatives in Mexico, the United States, or both countries that would  reduce the number of days that transboundary flows occur, including  by diverting more wastewater through the South Bay plant to prevent  its release in the United States. The alternatives range in cost from $8  million to $236 million. USIBWC, the Mexican Section, the EPA, the  Mexican National Water Commission, and the Tijuana water utility  also coordinated on the study, which was completed in July 2019.

Even with the efforts of IBWC and others, raw sewage continues to be  released in both watersheds due to deteriorating and insufficiently  maintained sewage infrastructure primarily in Mexico, with the exception  of the IOI in the United States. In the Santa Cruz River, the presence of  raw sewage in Nogales Wash and the river continues to threaten public  health and the survival of fish and wildlife, including endangered species,  according to representatives of Friends of the Santa Cruz River, a local  nonprofit organization. Similarly, raw sewage containing E. coli and  other pathogens continues to flow into the Tijuana River and watershed  primarily during storm events or breaks in infrastructure in Tijuana,  contributing to public health concerns and beach closures in southern  California.

To address the continuing release of raw sewage due to pipe breaks and  pump failures, at an IBWC meeting in spring 2019, USIBWC proposed  the development of a rapid response team comprised of technical experts  from both countries that could immediately respond to infrastructure  problems, such as pipe breaks and pump failures. This team would take  actions to mitigate sewage leaks along the border such as those in  Nogales, Sonora, and Tijuana. For example, the team would respond  immediately to situations in which a pipe break in Mexico causes  wastewater to flow into the United States and would put in place  appropriate diversions and equipment to repair the break. Members of the  team would come from both countries, and funding for their deployment  would come primarily from the United States. USIBWC has not estimated  the cost to form and annually support the binational team.

The principal engineers from both USIBWC and the Mexican Section  have agreed to start building the team with their respective staff,  according to a USIBWC official. However, this agreement is informal, and  IBWC has not taken the necessary steps to formalize the team. Such  steps could include preparing a minute. Specifically, Minute 261 states  that for each border sanitation problem, IBWC is to prepare a minute  identifying: (1) the problem; (2) the conditions which require solution; (3)  specify quality standards that should be applied; (4) the course of action  that should be followed for its solution; and (5) the specific time schedule  for its implementation. According to IBWC officials, the benefit of a  minute is that it functions as a formal agreement between the respective  governments, encouraging them to provide greater support through  funding and other resources to ensure the solutions and projects are  implemented.

According to USIBWC officials, they also have alternatives to negotiating  a minute, such as issuing a joint report, and a minute may not be  necessary for the countries to formalize their commitment. For example,  IBWC could exchange formal letters signifying their intent to form the  team or issue a joint report written by each IBWC section’s principal  engineers. By formalizing a binational rapid response team to address  sewage infrastructure failures along the U.S.-Mexico border, including the  watersheds around the Nogales and South Bay plants, USIBWC would  have better assurance that it is able to more effectively address the  urgent and recurring sewer breaks and pump failures in Mexico that  contribute to raw sewage spills.

USIBWC States That It Lacks Authority to Address Unmanaged Stormwater Problems, and Has Not Used Long-Term Capital Planning That Includes Key Planning Principles

USIBWC has taken some actions to address water quality problems at  both plants, but USIBWC and the Mexican Section have not taken actions  to address unmanaged stormwater flows and their associated water  quality problems. USIBWC officials stated that the agency does not have  the authority to manage stormwater problems in the Santa Cruz River  Basin or Tijuana River Valley watersheds without direction by Congress.  Further, USIBWC has not fully incorporated key planning principles for  long-term capital planning that would help it identify alternative  approaches for resolving the ongoing water quality problems along the  border.

Unmanaged Stormwater Complicates Water Quality Management in the Two Watersheds, and USIBWC Has Not Taken Actions to Address the Issue

USIBWC and others have taken some actions to address the water  quality problems that exist in the two watersheds, but USIBWC has not  taken actions that include identifying alternatives to address stormwater  and stormwater quality in the Santa Cruz River Basin watershed or in the  Tijuana River Valley watershed. As a result, unmanaged stormwater flows  largely untreated downhill from Mexico, carrying bacteria, trash, and  sediment into the lower portions of the Santa Cruz River Basin and  Tijuana River Valley watersheds where the Nogales and South Bay plants  are located, threatening key infrastructure and complicating water quality  management in the watersheds. The stormwater carries the pollutants  across the border, depositing them in the river channel, shorelines,  nearby wetlands, and—in the case of the Tijuana River—ultimately the  ocean, causing public health and environmental concerns in the United  States. In addition, stormwater can damage plant infrastructure.

Even with USIBWC Actions, Unmanaged Stormwater Threatens Key Infrastructure and Carries Bacteria into the Nogales Wash

The Nogales Wash is the main drainage for the cities of Nogales, Sonora,  and Nogales, Arizona. Stormwater from the upper watershed flows into  the wash and crosses the border, carrying bacteria and sediment into the  United States. According to IBWC officials, because Nogales, Sonora,  does not have adequate stormwater sewers, Mexican citizens remove  manhole covers to allow stormwater to drain from the streets into the  sanitary sewers during heavy rainstorms. The IOI essentially becomes a  combined sewage system—one in which wastewater and stormwater flow  in the same pipelines—even though it was not designed as such,  according to USIBWC officials. The excess stormwater causes increased  pressure in the IOI that is released when the manholes in the United  States overflow, sending sewage into the streets of Nogales, Arizona. In  July 2018, ADEQ documentation noted that Nogales, Sonora,  experiences frequent flooding during heavy rain events in the summer  and uses the IOI to mitigate flood events, which results in releases of  untreated sewage into the residential and business neighborhoods in the  City of Nogales, Arizona and the Santa Cruz River watershed. For  example, in 2017, Santa Cruz County Health Services and the Arizona  Department of Health Services released public health advisories for  elevated E. coli for the City of Nogales, Arizona, due to untreated sewage  leaking from the IOI. According to one of these advisories, stormflows are  typically high in pollutants that can be harmful to human health such as  bacteria and pathogens.

Unmanaged stormwater flowing into the Nogales Wash can destabilize  the IOI, which runs inside or below the wash, from the border to the  Nogales plant. Stormwater rushing down the wash erodes and removes  natural and manmade materials covering the pipeline, such as the  cement panels lining the middle portion of the wash (see fig. 7). For  example, in July 2017, flooding in the Nogales Wash eroded the soil  around a manhole in the IOI, partially shearing the pipe and causing  untreated wastewater to flood into the wash and into the streets of  Nogales, Arizona, resulting in elevated levels of E. coli in the wash and  Santa Cruz River. As a result, the Arizona Governor’s Office declared a  State of Emergency in Santa Cruz County and sent a notice of the  Nogales plant’s permit violation to USIBWC.

To date, USIBWC’s actions have focused on emergency repairs and  cleanup when untreated sewage has leaked from the IOI into the Nogales  Wash and Santa Cruz River. During the July 2017 event, for example, to  prevent further contamination of the wash due to the release of raw  sewage leaking from the broken section of the IOI, USIBWC hired a  contractor to install a bypass system to divert the raw sewage spilling into  the wash to the Nogales plant for treatment. Other stakeholders also took  action. For example, at the request of the Arizona governor’s office, the  Corps stabilized earthen banks along the Nogales Wash that had eroded.  The Arizona Army National Guard and Arizona Department of  Transportation also took part in similar efforts.  In general, the Nogales Wash is not regularly maintained to stabilize the  earthen banks and concrete panels to prevent erosion. According to  USIBWC officials, operations and maintenance of the Nogales Wash and  management of stormwater in the Nogales Wash is a municipal  responsibility and not the responsibility of the IBWC. As a result, USIBWC  has not taken action to manage the Wash to prevent stormwater damage  to the IOI. Instead, it has—as with the example above—sought to bring in  other federal agencies that USIBWC says have authority over domestic  water management. However, Nogales city managers do not accept  responsibility for managing the wash, stating that it is IBWC’s  responsibility.

USIBWC and other federal agencies have conducted some studies in  Mexico to address stormwater management in the watershed. For  example, USIBWC contracted the Corps to conduct an evaluation to  develop measures to reduce the threat of flooding and alternatives to  reduce potential flood damage in Nogales, Sonora. The study was  completed in 2004. Based on the recommendations in the evaluation,  Nogales, Sonora, and the Mexican federal water agency, constructed 14  dams and detention basins from 2008 through 2015. However, according  to USIBWC officials, the basins that are in Mexico and maintained by the  local utility are full of sediment and have not been cleared because the  local Mexican utility does not have funds to maintain them. In addition,  USIBWC and the U.S. Geological Survey have collaborated on joint  studies of the watershed surrounding Nogales, Sonora, for many years  according to USIBWC officials. For example, one study completed in  2016 was to be the basis of further work to identify stormwater  management projects, but that work has not been planned or conducted.  (See app. IV for details of additional studies.)

In the absence of an entity that regularly maintains the wash, the IOI is  still threatened when stormwater runs through the wash. IBWC has not  contracted for or conducted a study to identify long-term solutions to the  stormwater quality problems in the watershed, like was done with the  Tijuana River Diversion Study. Instead, since 2005, USIBWC has  responded to events that threaten the IOI as they occur at the request of  the City of Nogales, Arizona, and used an emergency response authority  that is applicable to the U.S.-Mexico border, according to USIBWC  officials. The Mexican Section also has not addressed maintenance of the  already insufficient stormwater conveyance infrastructure in Nogales,  Sonora. Without resolution, the unmaintained wash and inadequate  stormwater infrastructure in Mexico threaten the stability of the IOI with  additional stormwater damage.

Even with IBWC Actions, Unmanaged Stormwater Carries Trash, Sediment, and Bacteria throughout the Tijuana River Valley Watershed

Stormwater carries trash into the canyons that cross the border area, as  well as bacteria from illegal sewer connections and infrastructure breaks  in Tijuana, and sediment that erodes from the steep hills of Tijuana. As  part of routine operation and maintenance, USIBWC annually removes  trash and clears sediment from the grates in the South Bay plant’s five  canyon collectors according to agency officials (see fig. 8).

The pollutants carried in the transboundary stormwater also cause  ongoing degradation to the riparian and estuarine habitats within the  lower Tijuana River Valley, impacting ecological diversity, wildlife, and  ceremonial and recreational use of the area. For example, from 2003  through 2017, the City of Imperial Beach, California, closed public  beaches for at least one-quarter of the year and half the year in some  years due to bacterial contamination in the Tijuana River, according to  city officials. Although the parties dispute the source of pollution causing  the closures, the raw sewage that enters into the Tijuana River Valley and  flows with stormwater into the ocean is a likely source of pollution.

In response to the bacteria and trash problems caused by flows from  Mexico into the Tijuana River Valley, the California Regional Water  Quality Control Board, San Diego Region, initiated the development of  two TMDLs—for bacteria and trash—for the Tijuana River. If the TMDLs  are applied, USIBWC would be responsible for meeting the TMDL  requirements, according to a California state official; USIBWC  disagrees.  If it were subject to a TMDL, USIBWC would be expected to  oversee the trash collection and removal in the United States even if the  trash originated in Mexico. USIBWC maintains that its ownership of the  Tijuana Flood Control Project does not make it responsible for the quality  of water flowing in that project from Mexico under the Clean Water Act.  As of November 2019, the issue of whether USIBWC should take action  to resolve these pollutant problems is in litigation.

In 2015, IBWC also negotiated a minute to address stormwater effects in  the Tijuana River Valley, Minute 320, General Framework for Binational  Cooperation on Transboundary Issues in the Tijuana River Basin.  According to USIBWC officials, the minute was developed after local  stakeholders in California asked Mexico to take action to address  stormwater problems in the United States. Mexico responded that it  participates in binational solutions to issues through IBWC. Under Minute  320, the United States and Mexico acknowledged that binational  coordination is required to address stormwater flows that carry bacteria,  trash, and sediment, as well as other pollutants that threaten the Tijuana  River Basin. growth of aquatic vegetation and  decrease spawning areas and habitats for  fish and other organisms.   rubber, and construction material—settles  on the bottom of waterways, affecting  bottom feeding organisms.

In response, IBWC formed three binational working groups composed of  local, state, and non-governmental stakeholders to conduct studies to  identify the sources of bacteria, trash, and sediment that stormwater flows  carry into the Tijuana River Valley. The working groups are tasked with  recommending solutions to the problems based on the studies’ findings.  However, Minute 320 did not set a timeline for completion of the studies  nor did it identify sources of funding for potential projects recommended  by the working groups. According to USIBWC officials, Minute 320  anticipates that there may be variety of sponsors and funding resources  for projects recommended by the working groups. The three groups  stopped meeting in 2017. In June 2019, the water quality and sediment  groups resumed meetings, but as of September 2019, the trash working  group had not reconvened. According to USIBWC officials, as of  November 2019, IBWC is convening a meeting of a reconstituted Minute  320 Binational Core Group, following up on stakeholder  recommendations to re-establish and strengthen the Minute 320 process:

Water quality working group. The water quality group is working on  an ongoing binational water quality monitoring program that began in  December 2018 and was to end in November 2019. The group is  sampling sewage and other flows at various locations in the United  States and Mexico to establish baseline data for pollutants in the  waters of the Tijuana River watershed according to USIBWC officials.

Sediment working group. The sediment group is working on an  ongoing sediment detention feasibility study funded by USIBWC to  identify the most effective means of sediment management within the  Tijuana River channel. The sediment working group had  recommended the study. USIBWC estimates the cost of removing  sediment at $15 million per year, based on an estimated 492,000 tons  of sediment entering the river each year and about three-quarters of it  being removed. According to USIBWC officials, the sediment working  group expects to complete the study in early 2020.

Trash working group. The working group has developed the scope  of work for a binational study of trash booms in different sites along  the Tijuana River. It is waiting on funds to perform a feasibility study.

USIBWC and several state and local agencies have taken further actions  to address these water quality problems in the Tijuana River Valley  Watershed, including the following:

Constructing a temporary earthen berm in the Tijuana River  Channel. In 2018, USIBWC constructed a temporary earthen berm in  the U.S. section of the concrete channel of the Tijuana River, close to  the border. The purpose of the berm was to hold back low-volume,  dry-weather flows contaminated with untreated sewage; however,  some sediment and sewage still enters the Tijuana River Valley  during high-volume flows or storm events because those flows  permeate the berm according to USIBWC documents. USIBWC  officials said the berm is just a temporary measure to capture low- volume flows of sediment and trash during dry weather and is not  intended as a long-term solution for the river channel.

Monitoring water quality in the Pacific Ocean. To understand the  sources of beach pollution, USIBWC contracts with the City of San  Diego to regularly monitor water quality in the Pacific Ocean, in  particular around the discharge points for the city’s wastewater  treatment plant and the South Bay plant. Starting in 2018, the City of  San Diego and USIBWC began a joint program to track the extent of  dispersion of sediment into the Pacific Ocean where the Tijuana River  empties into the ocean according to USIBWC and City of San Diego  officials.

Collecting and disposing of trash and sediment. Several state and  local agencies collect and remove sediment from their land parcels in  the Tijuana River Valley. For example, California State Parks placed a  boom across the floor of one of the five canyons to collect trash and  sediment from stormwater flows (see fig. 9). Since 2015, California  State Park employees annually collect and remove trash and  sediment from the rack and disposes of it at a local landfill and quarry,  at a cost of $1.8 million per year. In addition, the U.S. Customs and  Border Protection agency also removes trash and debris from grates  associated with four of the five cross-border canyons as often as  necessary to protect the health of agents conducting daily patrol  operations.

Identifying projects to reduce sewage, trash, and sediment, in  the Tijuana River Valley. The County of San Diego is funding an  assessment to identify and prioritize potential projects that could be  implemented in the United States to improve the water quality in the  Tijuana River Valley by addressing transboundary flows of sewage,  trash, and sediment. The county expects the assessment to be  completed in March 2020, and intends to work with partners in the  region to identify funding and other resources necessary to implement  the highest priority projects, according to San Diego County officials.  (See app. IV for additional studies.)

As of October 2019, USIBWC officials said they were reviewing  alternatives outlined in the 2019 study of alternatives to expand or adapt  the diversion structure for the South Bay plant to address transboundary  sewage flows. In December 2019, local government officials in California  passed a resolution supporting a set of projects to be built on the U.S.  side of the border to resolve the water quality problems. The mayors of  several California municipalities endorsed EPA to receive funding to  construct projects on the U.S. side of the border to help resolve water  quality problems in the Tijuana River basin. In January 2020, a large trash  buildup in a storm drain on the border caused putrid water to back up in  Tijuana, highlighting the nature of the trash and sediment problem in the  upper watershed, which also affects the lower watershed. In December  2019, a congressional committee identified the need for EPA to lead the  efforts to resolve these problems.

According to USIBWC officials, while the most cost-effective solutions are  in Mexico, the Mexican government lacks resources to make all of the  infrastructure improvements. However, officials told us the proposed  solutions on the U.S. side of the border may be more expensive or  difficult to implement in part due to other constraints to the United States.  For example, one of the alternatives would divert untreated sewage to the  South Bay Ocean Outfall for direct discharge into the Pacific Ocean, but  the discharge likely would not meet Clean Water Act standards.  According to USIBWC officials, solutions that lead to violations of Clean  Water Act standards would not be acceptable to USIBWC, EPA, or other  U.S. stakeholders.

According to EPA officials, USIBWC has expertise in operating and  managing water and wastewater infrastructure, while EPA has expertise  in addressing water pollution. In addition, EPA officials stated that  USIBWC’s binational presence and ability to work across the border is  important to deal with operations and maintenance issues, such as  clearing stormwater channels. EPA officials stated that their role in  coordinating with USIBWC is important for identifying and addressing  specific water quality problems. For example, joint efforts by both  agencies through the Mexicali Binational Sanitation Observation and  Technical Committee led to successful solutions to wastewater pollution  and trash problems through joint monitoring and site visits, according to  EPA officials.

USIBWC States That It Lacks Authority to Address Stormwater Quality Problems in Each Watershed, and Long- Standing Problems Remain

USIBWC officials stated that the agency does not have the specific  authority to manage stormwater problems in the Santa Cruz Basin or  Tijuana River Valley watersheds without the direction of Congress.  Minute 261 states that IBWC shall “give permanent attention to border  sanitation problems and give currently existing problems immediate and  priority attention.” In addition, OMB Circular A-94 calls for agencies to  assess the benefits and costs of alternative projects. Although IBWC,  USIBWC, and others have taken some actions to address stormwater  quality problems in the Santa Cruz River Basin and Tijuana River Valley  watersheds, such as conducting studies of stormwater and building some  retention basins, the problems have nevertheless continued to occur over  many years, and no entity has taken action to identify alternatives, cost  estimates, funding sources, or time frames for implementing them.

USIBWC officials stated that feasibility studies and analyses are  necessary steps in justifying requests for funding a project and  investigating the cost and technical feasibility of a project. While USIBWC  has conducted some feasibility studies on different individual solutions, it  has not done a comprehensive study to recommend any overall solutions  to address the transboundary stormwater problems of bacteria, trash, and  sediment in either watershed.

According to USIBWC officials, previous projects it has built in Nogales  and South Bay were developed with federal, state, and local partnerships  and with congressional approval. In particular, USIBWC officials stated  that the agency does not have specific authorization for stormwater  management in the watersheds surrounding the Nogales and South Bay  plants because the 1944 Treaty and accompanying legislation did not  authorize that the agency carry out projects for stormwater management  along the border. USIBWC’s role in addressing certain transboundary  stormwater flows and associated water quality problems is in dispute in  ongoing litigation involving the Santa Cruz and Tijuana River basins, and  USIBWC officials stated that they would not take action to resolve the  stormwater quality problems without congressional direction. Yet without  action, the long-standing environmental and health problems associated  with transboundary stormwater flows in the watersheds of both rivers will  continue. Under these circumstances, Congress has the opportunity to  provide direction and specific authorization for USIBWC to take action.  Such action would include identifying alternatives, cost estimates,  funding, and time frames.

USIBWC Has Not Fully Incorporated Key Capital Planning Principles That Would Help Identify Alternative Approaches to Address Water Quality Problems in Both Watersheds

USIBWC has not fully incorporated key capital planning principles that  would help identify alternative approaches to address water quality  problems in the Santa Cruz or Tijuana River Valley watersheds. In 2019,  OMB issued a Capital Programming Guide that supplements Circular A- 11, which provides guidance on capital programming, including key  capital planning principles (see table 1).

In February 2007, we reported that OMB’s guidance on capital planning  requires long-range planning and a disciplined decision-making process  as the basis for managing assets to achieve an agency’s goals and  objectives. We also reported that the planning phase is the most  important for the capital decision-making process and that it links capital  asset investments to an organization’s overall mission and long-term  strategic goals. We emphasized that agencies should evaluate a full  range of alternatives to bridge any performance gap and recommended  that Congress require agencies to develop long-term capital plans and  submit them for review. Furthermore, in January 2016, we reported that  asset management planning for water utilities includes key components  such as assessing the current state of their assets (for example pipelines  and treatment plants), incorporating life-cycle costs, and developing a  strategy for the long-term funding of the repair and replacement of their  assets.

In our review of documents and interviews with USIBWC officials, we  found that the agency incorporates aspects of the key planning principles  in its capital planning and budgeting but has not fully incorporated the  principles. For example, the agency has a strategic plan that identifies its  goals, including a goal to improve the quality of water along the border.  We have stated, along with OMB, the importance of linking capital asset  investments to an organization’s overall mission and long-term strategic  goals. However, in its capital planning and budget process, USIBWC  does not fully assess or identify future needs, as called for in OMB’s key  capital planning principles. Those principles state that a needs  assessment identifies the resources needed to fulfill both immediate  requirements and anticipated future needs, based on the agency’s goals  and objectives.

According to USIBWC officials, the agency conducts and funds capital  planning on a project-by-project basis because it uses year-end money to  fund studies or evaluations to identify project needs or alternatives.  Specifically, USIBWC engineers identify the need for a project, and the  agency identifies year-end appropriations to pay for a study of that  project. For example, in one case described by a USIBWC official, the  agency contracted with the Corps of Engineers to conduct a study of  USIBWC flood control levees and their condition. The agency used year- end funds in its Salaries and Expenses budget line item to pay for the  study, and USIBWC officials stated that the study has since been the  basis for its request for levee repair and replacement projects.

In addition, we found that USIBWC conducts alternative evaluations of  potential projects, as directed by OMB’s guidance that states an  evaluation should be conducted of a wide range of alternative approaches  to determine how to bridge performance gaps in capital infrastructure.  According to USIBWC officials, the agency is considering a range of  alternatives and plans to conduct an analysis of costs associated with the  projects, as leading practices for benefit-cost analysis and alternative  comparison suggest. For example, the contractor for the 2019 study of  alternatives to expand or adapt the diversion infrastructure for the South  Bay project has assessed alternatives and costs to reduce the number of  days that transboundary flows cross the border bringing bacteria, trash,  and sediment into the United States. However, this was done for one part  of the water quality problems created by transboundary flows and will not  solve the problems associated with water quality problems created by all  stormwater flows. USIBWC has not evaluated alternative approaches or  costs for managing stormwater and associated water quality problems in  the Santa Cruz River Basin and Tijuana River Valley watersheds that will  continue to impact water quality along the border, and states it has no  responsibility to do so.

USIBWC also has not developed a comprehensive, long-term capital plan  to help achieve its strategic goal for water quality. Instead USIBWC has  elements of a plan, such as asset management documents for each of its  two wastewater plants that identify key equipment replacement costs and  schedules. The Nogales plant manager provides USIBWC officials with  10-year cost projections for major equipment, which include information  on cyclic maintenance and life-cycle replacements. The operator of the South Bay plant prepares a 5-year plan that assesses the condition of  equipment and recommends repair and replacement. However, neither  plan identifies gaps in infrastructure needed to resolve water quality  problems that are separate from the plants and their normal operation,  such as stormwater problems that destabilize the Nogales plant’s IOI  pipeline and cause polluted water to be diverted around the South Bay  plant. USIBWC states it has no responsibility to do so. As noted above,  USIBWC’s role in addressing certain transboundary stormwater flows and  associated water quality problems is in dispute in ongoing litigation  involving the Santa Cruz and Tijuana River Valley basins.

Under OMB’s capital planning principles, conducting long-term capital  planning should enable USIBWC to more systematically assess its long- term needs, including its future needs and identify alternative approaches  and costs to address stormwater problems in the watersheds.  Furthermore, a long-term capital plan should identify the capital projects  that USIBWC needs to achieve the strategic goal it seeks to  accomplish—in this case, improvement of water quality along the border.  In February 2007, we reported that a long-term capital plan can include  elements such as (1) a baseline assessment and identification of  performance gaps; (2) justification of spending on proposed new assets;  (3) the basis for selecting proposed assets; and (4) cost schedules and  performance goals. In addition, OMB’s capital planning guidance states  that each capital asset should have an operations and maintenance plan  that outlines the procedures and responsibilities for scheduled preventive  and regular or routine corrective maintenance. Currently, USIBWC has  not comprehensively developed this information into a long-term capital  plan. A long-term capital plan would help USIBWC budget for capital  projects and investments in the watersheds and provide justification for  funds requested for capital investment in future water quality projects.

OMB Circular A-11 also encourages agencies to use a summary of the  capital plan for budget justification to OMB, congressional authorizations  of projects, and justification for congressional appropriations. In  November 2019, OMB issued a memorandum to federal agencies that  reinforced the need to implement the capital programming guidance in  OMB Circular A-11 that agencies develop, document, and implement a  capital planning process. In its budget process, USIBWC requests  funding for individual capital projects for the budget year in which the  projects are needed. Specifically, for each annual budget cycle,  USIBWC’s Principal Engineers provide information to agency budget  officials on the projects they have identified and funds needed for each  plant. USIBWC budget officials use this information to prepare budget  requests that are then reviewed by the State Department and OMB, and,  ultimately, Congress. According to USIBWC’s Administrative Officer, the  agency previously provided capital needs in an attachment to the budget  requested in OMB Circular A-11. The official told us preparing the  information was time-intensive yet helpful. For example, the information  helped the agency understand the scope and life-cycle costs of a project.  However, when OMB no longer collected agencies’ information, USIBWC  stopped providing the information in its budget. According to  Department of State budget examiners, USIBWC notifies them of  potential infrastructure projects and funding needs; however, this  information is not included in the agency’s budget request and is  therefore not available to identify funding needs. According to USIBWC  officials, they do not provide the information in a budget request to State  because they are told to conduct agency operations within a flat budget.  By conducting long-term capital planning for the Santa Cruz River Basin  and Tijuana River Valley watersheds, following the principles in OMB  Circular A-11, USIBWC would have more information to address the  water quality problems resulting from unmanaged stormwater in either the  Santa Cruz River Basin or Tijuana River Valley watersheds; and could  provide the information to State, OMB, or Congress as part of annual  budget deliberations.

USIBWC and the Mexican Section of IBWC have successfully developed  binational solutions to water quality issues along the U.S.-Mexico border,  including constructing two international wastewater treatment plants to  treat raw sewage that would otherwise flow into the United States.  Nonetheless, in the decades since construction of the plants, the  communities along the border have experienced exponential growth in  populations and development that has, exacerbated by aging and  deteriorating infrastructure, resulted in ongoing transboundary flows of  raw sewage, trash, and sediment. USIBWC and the Mexican Section  have discussed some alternatives to deal with ongoing water quality  problems at both plants and in both watersheds. However, water quality  problems, including unmanaged and untreated stormwater, bring  bacteria, trash, and sediment into the lower watersheds in the United  States. To date, USIBWC and the Mexican Section have only studied or  monitored the problems; they have not taken actions to resolve the  problems by proposing and analyzing alternatives, analyzing costs,  identifying solutions, or establishing time frames. The long-standing  environmental and health problems associated with transboundary  stormwater flows in the watersheds of both rivers continue. USIBWC  officials’ statement that it lacks the authority to resolve the problems  suggests that congressional direction may be needed to specifically  authorize USIBWC to take action. This action could include identifying  alternatives, cost estimates, funding, and time frames. Such action would  help address the environmental and health problems associated with  transboundary stormwater flows in the Santa Cruz River Basin and the  Tijuana River Valley watersheds.

To help address some of the infrastructure problems in Mexico that cause  the transboundary flows—such as pipe breaks and pump failures— USIBWC has proposed the development of a binational rapid response  team comprised of technical experts in both countries that would  immediately respond to infrastructure problems. However, it has not taken  the necessary steps to formalize the team within IBWC. By formalizing  the binational rapid response team to address sewage infrastructure  failures along the U.S.-Mexico border, USIBWC would have better  assurance that it is able to more effectively address the urgent and  recurring sewer breaks and pump failures in Mexico that contribute to raw  sewage spills.

In addition, USIBWC has not fully incorporated key capital planning  principles that would help identify alternative approaches for the agency  to address stormwater problems in the Santa Cruz River Basin or Tijuana  River Valley watersheds. By conducting long-term capital planning in the  Santa Cruz River Basin and Tijuana River Valley watersheds, following  the principles in OMB Circular A-11, USIBWC would have better  information to address the water quality problems resulting from  unmanaged stormwater in either the Santa Cruz River Basin or Tijuana  River Valley watersheds. USIBWC would also have capital planning  information available to provide to State, OMB, and Congress, as part of  the budget process, as directed in the 2019 OMB memorandum.

Congress should consider providing direction and specific authorization  for USIBWC to take action to resolve the long-standing water quality  problems associated with transboundary stormwater flows in the Santa  Cruz River Basin watershed, including identifying alternatives, cost  estimates, funding sources, and time frames, in coordination with federal,  state, and local partners. (Matter for Consideration 1)

Congress should consider providing direction and specific authorization  for USIBWC to take action to resolve the long-standing water quality  problems associated with transboundary stormwater flows in the Tijuana  River Valley watershed, including identifying alternatives to include cost  estimates, funding sources, and time frames, in coordination with federal,  state, and local partners. (Matter for Consideration 2)

We are making the following two recommendations to the U.S.  Commissioner of the IBWC.

The U.S. Commissioner of the IBWC should work with the Mexican  Commissioner to formalize a binational rapid response team to address  sewage infrastructure failures along the U.S.-Mexico border, including the  Nogales and South Bay wastewater treatment plants. (Recommendation  1)

The U.S. Commissioner of the IBWC should direct USIBWC staff to  conduct long-term capital planning for the Santa Cruz River Basin and  Tijuana River Valley watersheds, following the principles in OMB Circular  A-11. (Recommendation 2)

We provided a draft of this report to USIBWC, EPA, and the Departments  of State and Homeland Security for comment. USIBWC provided written  comments, which are reproduced in appendix V. The other three  agencies did not provide written comments on our draft report; however,  they provided technical comments that we incorporated as appropriate.

In its written comments, USIBWC concurred with our first  recommendation that it work to formalize a binational rapid response  team to address sewage infrastructure failures along the U.S.-Mexico  border. The agency noted that it has held extensive consultations with the  Mexican Section of the IBWC, and once there is agreement on the  designated responsibilities and funding of the team, USIBWC will seek to  formalize the arrangement through a written agreement or exchange of  letters between the U.S. and Mexican Sections, approaches we outlined  in the report. USIBWC also noted that the United States and Mexico have  not agreed upon each country’s share of expenses and that the U.S.  financial contribution is subject to legislative approval and contributions,  including in-kind contributions, from domestic nonfederal entities.

USIBWC partly concurred with our second recommendation that the U.S.  Commissioner of the IBWC direct staff to conduct long-term capital  planning for the Santa Cruz River Basin and Tijuana River Valley  watersheds. The agency noted that it provided us the long-term capital  planning information previously required by the Office of Management  and Budget and that the practice had been useful. However, the agency  also noted that to the extent our report envisions USIBWC undertaking  long-term capital planning for (1) nonfederal infrastructure; (2)  infrastructure that does not yet exist; and/or (3) infrastructure that the  USIBWC is not yet authorized to construct or maintain, it does not concur.  USIBWC stated that Congress may not view it as the lead agency, and  therefore Congress does not need to provide it with the authorization to  oversee cross-border pollution matters. Regardless of whether Congress  considers USIBWC as the lead agency in resolving transboundary water  quality, the agency is a key player in managing water quality on the  border and has the infrastructure and organization that will be part of the  solution. To date, the agency has been more reactive than proactive in  participating in planning efforts and studies to resolve water quality  problems and has told us that it does not have the authority to do so. Yet,  without the information that USIBWC would generate by comprehensively  assessing its long-term needs, such as through long-term capital planning  efforts, Congress cannot authorize specific work that needs to be done.  We recommended that the agency conduct long-term planning, including  for infrastructure that does not exist and for infrastructure that is not yet  authorized specifically to address this problem. We continue to believe  that USIBWC should recognize its role along the border and, as we  recommended, start planning for it, including by undertaking long-term  capital planning for existing and potential future infrastructure and  identifying alternatives to address the long-standing water quality  problems.

The agency also commented on our two Matters for Congressional  Consideration in which we said that Congress should consider providing  direction and specific authorization for USIBWC to take action to resolve  long-standing water quality problems associated with transboundary  stormwater flows in the watersheds. In its comments, USIBWC stated that  it partly concurred with the Matters. USIBWC also stated that the phrasing  of the Matters suggests that Congress should assign USIBWC specific  duties and responsibilities, including identifying time frames for a  comprehensive solution of pollution problems associated with  transboundary stormwater flows and binational watershed management.  This is correct. In our report, we highlighted the role USIBWC plays along  the border and the infrastructure USIBWC manages and operates to  address transboundary flows from Mexico. Given the location of the  USIBWC’s wastewater treatment plants, along with its expertise and role  working with Mexico, the agency would need to be centrally involved in  any transboundary solution.

However, it is incorrect, as USIBWC’s letter further stated, that our  Matters imply that USIBWC would have the lead role in resolving water  quality problems along the border. USIBWC’s letter stated that while the  Matters acknowledge that USIBWC might coordinate with a wide range of  partners, the language implies that Congress would designate USIBWC  as the lead agency. Further, the agency stated that such a designation  may run counter to past and current congressional intent and reasoning,  as evidenced in very recent developments. In our matters, we stated that  Congress should authorize USIBWC to take action to resolve water  quality problems because it is a central actor in managing water and  water quality along the border and because, during the course of our  review, USIBWC stated that it needed specific congressional  authorization to manage stormwater problems and to construct and  maintain new infrastructure. We included the need for USIBWC to  coordinate its action with other agencies because USIBWC would not be  the sole lead actor. We note that USIBWC did not state what its role  would be.

Moreover, USIBWC stated that Congress may be in the process of  designating EPA as the lead agency in developing major new  infrastructure in the Tijuana Valley watershed to mitigate problems  resulting from transboundary flows from Mexico. USIBWC also cited a  recent bill to show that Congress is considering, consistent with proposals  from California stakeholders, an appropriation request for as much as  $300 million for the EPA to build this infrastructure. The agency stated  that the bill lists USIBWC as one of 11 eligible public entities with which  EPA may coordinate its efforts, as opposed to identifying the USIBWC as  the lead agency. It also stated that the United States-Mexico-Canada  Agreement Implementation Act accompanying this bill explains that EPA’s  designation as the lead agency was premised on Congress’s  determination that EPA has the expertise and experience necessary to  lead and coordinate efforts involving wastewater, stormwater, nonpoint  sources of pollution, and related matters in the Tijuana watershed. At a  minimum, USIBWC will be a key partner with EPA if it is given the  authority to help resolve stormwater quality problems in the Tijuana River  watershed. Yet, as discussed in our report, USIBWC stated it needs  congressional authorization to participate in addressing stormwater  issues along the border. We note that the bill to which USIBWC refers  does not specifically address USIBWC’s authority to develop and  implement stormwater projects near the border. Our report shows that  this authorization is necessary for the agency to take action, whether as a  lead agency or as an eligible partner that may coordinate with others. We  added a discussion of the bill in our report, as well as about the expertise  that EPA and USIBWC have to address transboundary flow problems.  Specifically, we described that according to EPA officials, EPA lacks the  expertise to construct and maintain water infrastructure projects on its  own. Further, EPA officials stated that EPA will need to carry out any  work in the area through contracts with other agencies, as EPA does not  have expertise in operating and maintaining water infrastructure, as  USIBWC does. EPA also noted that USIBWC is one of the only federal  agencies that works across the border because it has consistent  communication and contacts in Mexico.

Finally, USIBWC stated in its comments that the reasoning for  designating EPA in the bill and the accompanying act as the lead agency  for pollution reduction for the Tijuana River watershed—because of EPA’s  unique qualifications—also applies in any border area, including the  Santa Cruz watershed in Arizona. Again, our report showed that USIBWC  is a central actor in managing water and water quality on the border and  that congressional authorization is needed for USIBWC to help address  transboundary stormwater flows, including identifying alternatives for  solutions, in the Santa Cruz watershed. We did not change our Matters,  but added a discussion in our report of the proposed congressional  legislation to address the water quality problems in Tijuana specifically  and the expertise that EPA and USIBWC each bring to addressing  transboundary flow problems.

We are sending copies of this report to appropriate congressional  committees; the Commissioner of the U.S. Section of the International  Boundary and Water Commission; the Secretaries of Homeland Security  and State; the Administrator of the EPA; and other interested parties. In  addition, the report will be available at no charge on the GAO website at  http://www.gao.gov.

If you or your staff members have any questions about this report, please  contact me at (202) 512-3841 or gomezj@gao.gov. Contact points for our  Offices of Congressional Relations and Public Affairs may be found on  the last page of this report. Key contributors to this report are listed in  appendix VI.

Appendix I: Objectives, Scope, and Methodology

This report (1) describes the authorities and roles involved in developing,  managing, and sharing costs for the International Boundary and Water  Commission’s (IBWC) two international wastewater plants in the United  States; (2) examines factors that affect the operation of the two plants  and steps IBWC has taken to address these; and (3) examines the extent  to which the U.S. Section of the International Boundary and Water  Commission (USIBWC) has taken steps to address water quality  problems in the two watersheds, including through the use of key capital  planning principles.

To address these three objectives, we visited the Nogales International  Wastewater Treatment Plant (Nogales plant) in Arizona and the South  Bay International Wastewater Treatment Plant (South Bay plant) in  California. At each facility, we interviewed USIBWC officials and toured  each wastewater treatment plant and its associated infrastructure. We  also met with other federal, state, and local government officials and  representatives of non-governmental organizations to discuss USIBWC’s  management and operations of the plant. Specifically, in Arizona we met  with officials from the Department of Homeland Security’s Custom and  Border Protection (CBP), the City of Nogales, the Arizona Department of  Environmental Quality, the County of Santa Cruz, and the nonprofit  Friends of the Santa Cruz River. In California, we met with officials from  CBP; Environment Protection Agency Region 9; the California Water  Quality Regional Control Board; the City of San Diego; the County of San  Diego; the California State Parks; the City of Imperial Beach; and  Surfrider Foundation San Diego Chapter, Wildcoast, and 4Walls  International (all nongovernmental organizations). We visited USIBWC  Headquarters in El Paso, Texas, to meet with agency officials, including  the U.S. Commissioner and budget, engineering, and general counsel  staff. We also met with the Mexican Commissioner of the IBWC in Ciudad  Juarez, Chihuahua, Mexico.

To describe authorities and roles involved in developing, managing, and  sharing the costs of USIBWC’s two international wastewater plants in the  United States, we reviewed the 1944 treaty between the United States  and Mexico, Treaty Relating to the Utilization of Waters of the Colorado  and Tijuana Rivers and of the Rio Grande, and associated IBWC  minutes. For cost-sharing of operational and maintenance expenses at  the plants, we reviewed minutes between USIBWC and the Mexican  Section and a memorandum of agreement between USIBWC and the City  of Nogales, Arizona. We reviewed USIBWC’s budget for fiscal years 2003  through 2019, including appropriated funding information for fiscal years  2003 through 2019. We also met with budget officials at USIBWC and the  Department of State. To determine if these data are reliable, we  interviewed a USIBWC official about the source of the data and reviewed  documentation to determine that the data were sufficiently reliable for the  purposes of discussing USIBWC budget and project costs.

To examine factors, if any, that affect the operation of the two plants and  steps IBWC has taken to address these factors, we reviewed each plant’s  permit from the National Pollutant Discharge Elimination System, violation  notices, and USIBWC documentation, such as plans for projects to  resolve the violations. We interviewed USIBWC officials about their plans  and projects to resolve any water quality problems at the plants. We also  interviewed Arizona and California state environmental officials  responsible for developing and enforcing the permits, to discuss permit  violations and water quality problems at the plants and actions to resolve  them.

To examine the extent to which USIBWC has taken steps to address  water quality problems in the two watersheds, including using key capital  planning principles, we reviewed and analyzed IBWC minutes, USIBWC’s  annual financial reports for fiscal years 2015 through 2019, USIBWC’s  most recent strategic plan covering fiscal years 2011 through 2016, the  South Bay plant’s 5-year and Nogales plant’s 10-year equipment  investment plans, and documentation from USIBWC’s citizen forums in  each location. In addition, we reviewed prior GAO reports on federal  agency capital planning and asset management, the Office of  Management and Budget’s (OMB) Capital Programming Guide (Version  3.0) Supplement to OMB Circular No. A-11, and OMB’s 2019 guidance on  implementing agency-wide real property capital planning.  We compared  USIBWC’s capital planning efforts against OMB’s Capital Programming  Guide and past GAO reports on capital planning leading practices.  Further, we interviewed USIBWC officials and stakeholders at each plant,  including local government officials and environmental group  representatives, about the water quality problems and solutions they have  discussed. We also reviewed studies conducted in the two watersheds.

We conducted this performance audit from September 2018 to February  2020 in accordance with generally accepted government auditing  standards. Those standards require that we plan and perform the audit to  obtain sufficient, appropriate evidence to provide a reasonable basis for  our findings and conclusions based on our audit objectives. We believe  that the evidence obtained provides a reasonable basis for our findings  and conclusions based on our audit objectives.

Appendix II: International Boundary and Water Commission Minutes Related to the Two U.S. Wastewater Treatment Plants

Appendix III: Factors that Can Affect the Operations of the Nogales and South Bay Plants

This appendix provides information about some of the factors that can  affect the operations of the Nogales and South Bay plants.

For the Nogales plant, the factors that can affect the operations include:

Lack of heavy metal pretreatment. Numerous metal treatment and  plating facilities operate in Nogales, Sonora, Mexico. These facilities  directly discharge their wastewater, which contains heavy metals such  as chromium, zinc, and nickel, into the city’s sewer system. The heavy  metals are comingled with the other sewage and sent to the Nogales  plant (in Arizona) for treatment. In the United States, similar types of  facilities would be required to pretreat the wastewater to remove  metals and other pollutants before discharging it into the public sewer  system. In the United States, the mechanism used to limit industrial  discharges into a sewer system is a pretreatment program that can  ultimately cause dischargers to be shut off from the system or fined if  they do not limit the industrial contaminants in their discharges to the  system. While a municipal pretreatment program exists in Nogales,  Sonora, it is designed to meet Mexico’s minimum federal  requirements and is insufficient to detect and respond to the dumping  of industrial contaminants when they occur, according to the Arizona  Department of Environmental Quality documentation and officials.  According to U.S. Section of the International Boundary and Water  Commission (USIBWC) officials, the Nogales plant is not designed to  separate out heavy metals during its treatment processes, and as a  result the heavy metals contaminate the plant’s sludge. Furthermore,  due to the presence of heavy metals, USIBWC disposes of the sludge  at a municipal landfill, a process that is more expensive than other  disposal options, which has led to increased operational costs for the  plant. According to USIBWC officials, it would cost about $60 million  to update the Nogales plant to a tertiary treatment system that could  remove the heavy metals from the sludge.

Deteriorating sewage infrastructure in Mexico. Sewage  infrastructure in the City of Nogales, Sonora, is not adequately  maintained, according to USIBWC officials. As a result, USIBWC  officials told us that the amount of wastewater Nogales, Sonora,  sends exceeds the amount agreed upon in a minute between the two  sections. Although Nogales, Sonora, built a new plant—the Los Alisos  Plant—that can treat 5.5 million gallons per day, wastewater has to be  pumped uphill from Nogales, Sonora, into the plant. After the first year  of operation, the Mexican government could not maintain the plant  due to funding constraints, according to USIBWC officials. The pumps  responsible for delivering the wastewater uphill to the Los Alisos plant  continually break or fail. For example, as of July 2019, only one of the  five pumps at the Los Alisos plant was operational, according to  USIBWC officials. When these pumps fail, Mexico releases the 2  million to 4 million gallons per day of wastewater—which normally  would have been intercepted and sent to the Los Alisos plant— through the International Outfall Interceptor (IOI) to the Nogales plant.

Deteriorating infrastructure in the United States. The deteriorating  condition of the IOI has caused untreated sewage to periodically spill  into the Santa Cruz watershed and Nogales Wash. The IOI is over 45  years old, and according to USIBWC officials, the typical lifespan of a  similar pipeline is 50 years. Maintenance has been deferred because  of continuing disagreement between USIBWC and the City of  Nogales, Arizona, regarding which entity owns the pipeline and is  therefore responsible for its maintenance, according to USIBWC  officials. The IOI’s condition continues to worsen and requires a  significant amount of rehabilitation to address structural damage.  Erosion and corrosion are continuously occurring, according to a 2005  assessment of the IOI prepared for the City of Nogales, Arizona.  Specifically, gases released by the sewage corrode the pipeline, and  root intrusion and groundwater cause erosion. According to the 2005  assessment, half of the thickness of the pipe had been eroded and  corroded  For the South Bay plant, the factor that may affect the operations is:  Insufficient sewage infrastructure in Mexico. According to the  2019 study of alternatives to expand or adapt diversion infrastructure,  Tijuana has not built sufficient sewage infrastructure to serve the  area’s increasing population and urbanization, contributing to  transboundary sewage flows. According to USIBWC officials, the city  of Tijuana does not prioritize wastewater issues and is experiencing  exponential population growth and urbanization. As a result, areas of  Tijuana are not connected to the city’s sewer system. A 2017 study  prepared by a Mexican state agency estimated that over $340 million  would be required to fix and develop adequate wastewater treatment  and reuse systems for the city of Tijuana. When there are problems  with Tijuana’s treatment facilities, Tijuana diverts a portion of its  wastewater to be treated at the South Bay plant. If the South Bay  plant is not notified and does not shut down the pump and canyon  collectors, it may receive additional flows. While treating the excess  wastewater does not violate the plant’s National Pollutant Discharge  Elimination System permit, the plant is experiencing an increase in the  number of days that it treats flows above capacity, according to  USIBWC officials. This could eventually cause violations to occur as  the plant is not supposed to operate above capacity for prolonged  periods.

In addition, USIBWC officials stated that the South Bay plant is not  designed and operated to address some of the wastewater that flows into  the Tijuana River Valley watershed. These wastewater flows are due to:

Limited Tijuana Basin diversion infrastructure. The Tijuana Basin  diversion system is comprised of Mexican-operated Pump Station  CILA and the South Bay plant’s five canyon collectors. This system  captures dry-weather flows for treatment at the South Bay plant or a  wastewater treatment plant in Mexico. However, it is not designed to  capture high flows that result from pipe breaks or pump failures.  Specifically, the system has a peak capacity of 29 million gallons per  day, while Pump Station CILA can only operate at 23 million gallons  per day. To avoid affecting the South Bay plant’s wastewater  treatment operations, during incidents of high flows, Pump Station  CILA and the canyon collectors are shut off. During these events, the  water bypasses the South Bay wastewater treatment plant and flows  untreated into the Tijuana River and watershed. The Senate  committee report accompanying the Department of State, Foreign  Operations, and Related Programs Appropriations Act, 2019 required  the USIBWC to submit a report quantifying the total annual volume of  transboundary flows entering the United States from Mexico in the  Tijuana River watershed. USIBWC issued this report in August  2019.

Lack of maintenance for existing sewage infrastructure in  Mexico. A lack of maintenance for Tijuana’s existing sewage  infrastructure causes excess wastewater flows into the Tijuana River  according to USIBWC officials. For example, in August 2019,  USIBWC reported that on June 19, 2019, nearly 1.9 million gallons of  wastewater were released into the Tijuana River because trash  buildup at one of Tijuana’s pumps caused the pump to fail. In the  last 2 decades, according to a 2019 study, the local Mexican utility  that operates and manages the city’s sewage infrastructure has  invested in expanding the city’s wastewater collection infrastructure to  address direct dischargers or inadequate disposal practices,  according to USIBWC officials. However, the overall system has not  kept pace with the region’s rapid growth, nor has the existing  infrastructure in Mexico received sufficient maintenance. In addition,  the local utility that manages and operates Tijuana’s wastewater  system has a limited number of personnel. The study also reported  that existing personnel were “very knowledgeable, dedicated, and  creative in their efforts” to maintain and operate the sewage  infrastructure. Nonetheless, Tijuana’s existing sewage pipes  consistently break and its pump stations fail. Another 2019 study also  reported that the poor condition of critical wastewater infrastructure in  Mexico results in approximately 30 percent of Tijuana’s wastewater  enters the Tijuana River or Pacific Ocean without treatment.

Appendix IV: Studies of the Santa Cruz River Basin and the Tijuana River Valley Watersheds

Appendix V: Comments from the U.S. Section of the International Boundary and Water Commission

Appendix VI: GAO Contact and Staff Acknowledgments

In addition to the contact named above, Susan Iott (Assistant Director),  Heather Dowey (Analyst-in-Charge), Farah Angersola, Mark Braza,  Chuck Bausell, Tara Congdon, Carol Henn, Richard P. Johnson, Anika  McMillon, Sara Sullivan, and Kiki Theodoropoulos made key contributions  to this report.

The U.S. Section of the International Boundary and Water Commission manages two wastewater treatment plants along the U.S.-Mexico border that treat raw sewage, mostly from Mexico. But population growth and aging plant infrastructure allow stormwater to bring bacteria, trash, and sediment from Mexico into the U.S.—affecting public health and the environment in Arizona and California.

The Commission has not taken comprehensive steps to resolve the problem, so we recommended that Congress consider directing the Commission to identify alternatives—including cost estimates and funding sources—to help resolve continuing water quality problems.