Introduction


The Columbia River drains 259,000 square miles of the Pacific Northwest, and flows more than 1,200 miles from its headwaters in the Canadian Rockies of British Columbia. The river drains areas in Montana, Idaho, Washington, Oregon, and Wyoming, before flowing along the border of Washington and Oregon to its mouth at the Pacific Ocean. The rivers and streams of the Columbia River Basin carry the fourth largest volume of runoff in North America. The approximately 8 million people who live in the basin depend on its resources for their health and livelihood (Independent Scientific Advisory Board, 2007; U.S. Environmental Protection Agency, 2009a). Similarly, hundreds of fish and wildlife species, including 12 stocks of threatened and endangered salmonid species, rely on the ecosystem for their food sources, security, and habitat. Therefore, the Columbia River Basin is of environmental and cultural significance for all its inhabitants. 


With growing scientific concern about the health of the ecosystem, efforts have been increased to make the public aware of the presence of toxic contaminants in the environment and the unknowns with regard to the potential adverse effects of these contaminants on the inhabitants of the ecosystem. Contaminants are chemicals introduced to the environment in amounts that can be harmful to fish, wildlife, or people. Many of these contaminants enter the environment through the production, use, and disposal of numerous chemicals that offer improvements in industry, agriculture, medical treatment, and common household conveniences. 


Several studies have been completed throughout the Columbia River Basin in the past 10–20 years in an effort to characterize contaminant concentrations in water, sediment, and fish. In 2005, the U.S. Environmental Protection Agency (EPA) joined other Federal, State, Tribal, local, and nongovernmental organizations in forming the Columbia River Toxics Reduction Working Group in an effort to coordinate this work and share information. The goal of the group is to reduce toxics in the basin and prevent further contamination. In 2009, EPA produced the State of the River Report for Toxics to document the current knowledge in the basin with regard to certain classes of compounds, and to open communication for developing future solutions for addressing toxics reduction (U.S. Environmental Protection Agency, 2009a).


Through this process, the working group acknowledged that an adequate understanding of sources of these contaminants must precede development of efficient and effective toxic-reduction efforts. In a national survey of 139 streams in 1999–2000, organic wastewater contaminants were detected in 80 percent of the streams surveyed (Kolpin and others, 2002). Of the 95 contaminants analyzed, fecal steroids, insect repellants, caffeine, antimicrobial disinfectants, fire retardants, and nonionic detergent metabolites were commonly detected classes. In 2004–05, some of these same pharmaceuticals, antibiotics, and anthropogenic organic compounds (AOCs) were analyzed in samples collected from the main stem Columbia River near Portland and Longview (Lower Columbia River Estuary Partnership, 2007). Less than 20 contaminants were detected in these filtered-water samples at concentrations less than 1 microgram per liter (µg/L, parts-per-billion) range (Morace, 2006). This would suggest that the large volume of water flowing in the Columbia River dilutes the concentrations of these manmade contaminants. In contrast, when Nilsen and others (2007) analyzed surficial bed sediments in the lower Columbia River main stem and several tributaries, 49 different AOCs were detected, supporting the need to analyze multiple media when assessing contaminant issues. Nilsen and others (2007) detected endocrine-disrupting compounds (contaminants that block or mimic hormones in the body and cause harm to fish and wildlife) at 22 of 23 sites sampled, with concentrations in the parts-per-billion range. The studies hint at the presence of these contaminants in the environment, but the extent of their presence throughout the basin is poorly understood.

Interstate Highway 5 (I-5) bridge on the Columbia River from Hayden Island, Portland, Oregon, October 2009.

Recent research has raised questions about potential effects on fish, shellfish, wildlife, and human health from even trace exposure to these contaminants, including chronic effects (Kidd and others, 2007; Ings and others, 2011), reproductive disruption (Vajda and others, 2008; Colman and others, 2009; Jenkins and others, 2009), and physiological changes (Hoy and others, 2011). Little is known, however, about the extent of the environmental occurrence, transport, and ultimate fate of these contaminants in the Columbia River ecosystem. To efficiently and effectively reduce loadings of these compounds to the river, sources and pathways of contaminants need to be identified. Numerous studies have shown that WWTP effluent and stormwater runoff contribute contaminants to their receiving waters (Boyd and others, 2004; Kolpin and others, 2004; Glassmeyer and others, 2005; Phillips and Chalmers, 2009). These two pathways act as integrators of human activities and offer an area where changes could be made to lessen their effects on the environment. This study focused on WWTP effluent and stormwater runoff to characterize how potential contaminants could be contributed through these pathways. A better understanding of the way contaminants enter the Columbia River Basin may help water managers reduce of the occurrence of contaminants in the basin.


Purpose and Scope 


This report presents the results of a study to (1) assess contaminant concentrations directly contributed to the Columbia River through WWTP effluent and stormwater runoff from adjacent urban environments, (2) evaluate instantaneous loadings to the Columbia River Basin from inputs of this type, and (3) provide information to water managers and policy makers to help with decision making about future sampling efforts and reduction activities. The data from this study provide an initial assessment of a broad array of contaminants that to date have little information available on different sources in the Columbia River Basin. These data will be a useful first step to (1) identify the contaminants of highest interest, (2) indicate the most important sources of these contaminants, and (3) prioritize contaminant-reduction efforts.


This investigation resulted from a scientific and financial partnership between the USGS, Columbia River Inter-Tribal Fish Commission, Lower Columbia Estuary Partnership, Columbia Riverkeeper, and Northwest Environmental Defense Center, all agencies involved in the Columbia River Toxics Reduction Working Group.


First posted April 25, 2012