Water Resources Professional Project Reports

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Polychlorinated biphenyls (PCBs) have been detected with increasing frequency in water and fish tissue samples in the Rio Grande Basin above Cochiti Dam (RGBACD), which correlates with the use of improved analytical methods for quantifying PCBs. Levels of PCBs identified in some fish have exceeded levels considered safe for human consumption, resulting in a Fish Consumption Advisory' for Abiquiu and Cochiti Reservoirs and the Rio Grande from Pojoaque Creek to Frijoles Canyon (Bandelier National Monument). In June of 2007, the New Mexico Environment Department (NMED) listed seven water bodies in the RGBACD as impaired due to elevated concentrations of PCBs in fish tissue and water samples collected from the area. These actions, a review of PCB related research conducted within the RGBACD, and a comparison between Aroclor and congener analytical results initiated research investigating the following issues: 1) whether PCBs are more prevalent in water, sediment, and fish tissue samples now than determined in field studies prior to 1997, 2) where the most likely sources of PCB contamination in the RGBACD are located, 3) whether canyons on LANL property are contributing to PCBs in water and sediment within the Rio Grande and in fish at Cochiti Reservoir, 4) if sediment contamination poses a potential risk, and 5) the appropriate fish consumption limits for fish caught in Cochiti and Abiquiu Reservoirs. This paper describes a study that generated information related to the occurrence, distribution, and potential sources of PCBs in the RGBACD. Results from samples collected upstream and downstream of Los Alamos National Laboratory contradict previous research concluding it was not a major source of PCBs in fish tissue at Cochiti Reservoir. Concentrations in carp, catfish, rainbow trout, and walleye collected in 2006 by the NMED Surface Water Quality Bureau fall within the recommended monthly EPA fish consumption limit category. Preliminary recommendations to better characterize PCBs in the RGBACD are offered as a result of the study.

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polychlorinated biphenyls (PCB), Rio Grande Basin, PCB contamination, Cochiti Reservoir, Abiquiu Reservoir, Water Quality Act (New Mexico)


A Professional Project submitted in partial fulfillment of the requirements for the degree of Master of Water Resources, Water Resources Program, University of New Mexico.