The Donna Reservoir and Canal System sits near Donna, Texas in Hidalgo County. The EPA added it to the National Priorities List (NPL) in March 2008 after finding polychlorinated biphenyls (PCBs), a toxic industrial chemical, in sediment and fish tissue. The contamination likely came from a siphon more than 100 years old that may have been repaired in the 1960s with PCB-containing materials. PCBs are the only contaminant of concern at this site, and groundwater contamination is not a concern here.
The site is split into two operable units (OUs), which are distinct problem zones that get their own cleanup plans. The sitewide unit covers the broader area, and the source unit focuses on where contamination originates. The EPA chose a cleanup plan for the source unit in September 2018. That plan includes sediment removal, fish tissue and sediment monitoring, institutional controls to limit site use, disabling equipment in place, and disposing of excavated waste offsite. Between January and May 2020, workers dredged and removed over 24,788 tons of contaminated sediment and sent it to an approved offsite landfill. Confirmation samples from the remediated area all tested well below the PCB cleanup level of 0.043 mg/kg. The EPA has also conducted five rounds of fish removal using electroshocking methods, working with the U.S. Fish and Wildlife Service, with removals from 2020 through 2024.
Despite the completed dredging, the site is not yet protective of human health. The EPA's five-year review, completed September 5, 2024, found that PCB concentrations in fish tissue still far exceed safe levels, especially in bottom-feeding fish species. The Texas Department of State Health Services banned fish possession from the system in 1994, with a $500 fine for violations, and warning signs are posted at multiple locations. However, people continue to catch and eat fish from the site. The EPA is working on an improved public outreach program and better signage to address this. The EPA also plans to evaluate whether the old siphon is still releasing PCBs into the system, with that assessment expected in 2025 or 2026. Additional remedial work is estimated to continue through November 2028.
Community members can read the 2024 Five Year Review Report online or pick up a copy at the Donna Public Library Central Library at 301 S. Main Street, Donna, Texas. Other key documents, including risk assessments and the Record of Decision, are also available through the EPA's online system and at the same library. Residents with questions can contact the EPA's Community Involvement Coordinator or Remedial Project Manager directly using the contact information below.
