Investigating Polychlorinated Biphenyl (PCB) Concentrations and Loads in Albuquerque Stormwater Channels

Science Center Objects

In cooperation with the New Mexico County of Bernalillo, the U.S. Geological Survey (USGS) characterized polychlorinated biphenyl (PCB) concentrations and estimated potential loading into the Rio Grande from urban watersheds that are under the county’s jurisdiction.  Water and sediment samples were collected in 2017-18 from six sites within four stormwater drainage basins in the Albuquerque, New Mexico urbanized area for the analysis of PCB congeners and other water-quality constituents during dry and wet seasons.  Also, the rainfall-runoff model Arid Lands Hydrologic Model (AHYMO) was used to estimate stormwater discharge at two of the sample collection sites which were not affected by pump station operation. Along with the PCB analysis, the estimated discharge data were used to estimate total PCB stormflow event loads for eight events in these urban Rio Grande tributaries.  Precipitation input data for the model were collected from USGS gages.

PCB Project Field Photograph, USGS - New Mexico Water Science Center

Purpose and Scope

The U.S. Environmental Protection Agency’s (EPA) National Pollutant Discharge Elimination System (NPDES) permit program was introduced in 1972 and authorized by the Clean Water Act. The NPDES permit program works to control water pollution by regulating point sources that discharge into waters of the United States. Urbanized areas that subsequently discharge stormwater into large water bodies through municipal separate storm sewer systems (MS4s), like many of the urbanized areas of New Mexico, are considered point sources by NPDES standards and are therefore subject to regulation. Bernalillo County, which encompasses the city boundary of Albuquerque, New Mexico, and the designated Albuquerque urbanized area is subject to regulation under the EPA NPDES permitting process for stormwater runoff. The results described in this report provide insights into PCB concentrations and loadings in the Rio Grande, as well as the health of the Rio Grande as a whole, and can be used to assist in fulfilling the county’s NPDES permit requirements for the EPA. The map below displays the sample site locations.

Image of PCB Study Area Map, USGS - New Mexico Water Science Center

Results

PCBs were detected in 34 of 36 water samples at concentrations as high as 65.8 nanograms per liter and in 12 of 13 sediment samples at concentrations as high as 163,000 nanograms per kilogram dry weight. Six of the 36 water samples exceeded the New Mexico surface-water quality standard for protection of wildlife habitat and aquatic life of 14 nanograms per liter for PCBs. None of the water samples exceeded the U.S. Environmental Protection Agency’s National Pollutant Discharge Elimination System permit level limit of 200 nanograms per liter for PCBs in stormwater systems discharging into the Rio Grande.

Total PCB Concentration Thresholds, USGS - New Mexico Water Science Center

PCB concentrations in water samples in this study were not linearly related to antecedent precipitation or measured water-quality parameters, but PCB concentrations had a statistically significant positive Kendall’s tau correlation with total suspended solids for water samples and with total organic carbon for sediment samples. The PCB congener profiles indicate that sources to stormwater drainage basins in Bernalillo County originate both from legacy sources, such as Aroclors 1254 and 1260 (for example, in landfills and old building materials), and from current-use sources, such as PCB-11 (for example, in printed materials and packaging in urban litter or refuse).

Graph of PCB Aroclors, USGS - New Mexico Water Science Center