International Boundary and Water Commission: Opportunities Exist to Address Water Quality Problems, Report to Congressional Requesters [open pdf - 7MB]
From the GAO [Government Accountability Office] Highlights: "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 [International Boundary and Water Commission] to address these water quality problems. As part of this effort, USIBWC [U.S. Section of the International Boundary and Water Commission] 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."
Government Accountability Office: https://www.gao.gov/