|Donna Reservoir and Canal System||Donna, Texas|
The Donna Reservoir is a drinking water and irrigation storage reservoir located southwest of the City of Donna, Texas, in south-central Hidalgo County. The system consists of two mechanical (diesel) pumping facilities, a 11.3 kilometer-long main canal, a 400 acre reservoir (Donna Reservoir), and 168 miles of lateral canals and pipelines. The site consists of contaminated sediments within a five mile stretch in the Donna Canal and Reservoir System.
The Donna Reservoir and Canal System (DRCS) site is located in Hidalgo County in southern Texas just north of the Rio Grande River. The site includes the Donna Reservoir, the Donna Main Canal (aka First Main Lift Canal), the West and East Main Canals which extend north from the reservoir, and a series of interconnecting canals. Total Maximum Daily Load (TMDL) study data and 2001 Site Inspection samples show that polychlorinated biphenyl (PCB) concentrations routinely exceed background levels and state water quality standards in surface water sediments and health-based benchmarks in fish. The City of Donna has a drinking water intake located within the area of observed sediment contamination.
The Texas Commission on Environmental Quality (TCEQ) conducted sampling of the Donna Reservoir and canal system from April 9, 2001 through April 13, 2001 to document the presence or release of PCBs from soil, surface water or suspended sediments in the reservoir and canal . The contaminated sediment source extends approximately 5.75 miles and includes the Donna Main Canal (aka First Main Lift Canal) from the exit of the siphon on the north side of the Arroyo Colorado through the Donna Reservoir, and into the West and East Main Canals to the intake for the City of Donna. The hazardous substance associated with this source is polychlorinated biphenyl (PCB) Arochlor-1254.
Potential Impacts on Surrounding Community/Environment:
There is a risk to individuals eating fish contaminated with PCBs. PCBs are a human carcinogen. Previous sampling by the Texas Department of Parks and Wildlife has documented the presence of PCBs in fish tissue in the Donna Canal Reservoir System. A fishing ban for PCBs is in place for this segment of the watershed. This ban prohibits all persons from catching any fish from these waters. Despite the ban, residents are continuing to consume fish within this system. In addition, surface water intakes for the City of Donna lie within the area of PCB contaminated sediments. At this time water samples collected from the intakes have not contained concentrations of PCBs; however, the potential for future contamination exists.
Response Activities (to date):
The Texas Department of Health issued an aquatic life closure for the reservoir and main canal effective June 24, 1993. The closure, which is still in effect, prohibits the taking of all species of aquatic life from the canal and reservoir.
Need for NPL Listing:
The State of Texas referred the site to EPA because of the presence of elevated concentrations of PCBs in fish tissue in the Donna Canal Reservoir System. TCEQ and EPA evaluated other cleanup programs and no other viable options were available. EPA received a letter of support for placing this site on the NPL from the State of Texas.
[The description of the site (release) is based on information available at the time the site was evaluated with the HRS. The description may change as additional information is gathered on the sources and extent of contamination. See 56 FR 5600, February 11, 1991, or subsequent FR notices.]
For more information about the hazardous substances identified in this narrative summary, including general information regarding the effects of exposure to these substances on human health, please see the Agency for Toxic Substances and Disease Registry (ATSDR) ToxFAQs. ATSDR ToxFAQs can be found on the Internet at ATSDR - ToxFAQs (http://www.atsdr.cdc.gov/toxfaqs/index.asp) or by telephone at 1-888-42-ATSDR or 1-888-422-8737.