A.L. Haggland | Geology Reports

USGS2000

Predicting the probability of detecting organochlorine pesticides and polychlorinated biphenyls in stream systems on the basis of land use in the Pacific Northwest, USA

We analyzed streambed sediment and fish tissue (Cottus sp.) at 30 sites in the Puget Sound and Willamette basins in Washington and Oregon, USA, respectively, for organochlorine pesticides and polychlorinated biphenyls (PCBs). The study was designed to determine the concentrations of organochlorine pesticides and PCBs in fish tissue and sediment by land use within these basins and to develop an empirical relation between land use and the probability of detecting these compounds in fish tissue or sediment. We identified 14 organochlorines in fish tissue and sediment; three compounds were unique to either fish tissue or sediment samples. The highest number of organochlorines detected in both fish tissue and streambed sediment was at those sites located in watersheds dominated by urban land uses. Using logistic regression, we found a significant relation between percentage agriculture and urban land use and organochlorines in fish tissue. The results of this study indicate that organochlorine pesticides and PCBs are still found in fish tissues and bed sediments in these two basins. In addition, we produced statistically significant models capable of predicting the probability of detecting specific organochlorines in fish on the basis of land use. Although the presented models are specific to the two study basins, the modeling approach could be applied to other basins as well.

Environmental Toxicology and Chemistry↗

USGS1999

An assessment of stream habitat and nutrients in the Elwha River basin: implications for restoration

The Elwha River was once famous for its 10 runs of anadromous salmon which included chinook that reportedly exceeded 45 kilograms. These runs either ceased to exist or were significantly depleted after the construction of the Elwha (1912) and Glines Canyon (1927) Dams, which resulted in the blockage of more than 113 kilometers of mainstem river and tributary habitat. In 1992, in response to the loss of the salmon runs in the Elwha River Basin, President George Bush signed the Elwha River Ecosystem and Fisheries Restoration Act, which authorizes the Secretary of the Interior to remove both dams for ecosystem restoration. The objective of this U.S. Geological Survey (USGS) study was to begin describing baseline conditions for assessing changes that will result from restoration. The first step was to review available physical, chemical, and biological information on the Elwha River Basin. We found that most studies have focused on anadromous fish and habitat and that little information is available on water quality, habitat classification, geomorphic processes, and riparian and aquatic biological communities. There is also a lack of sufficient data on baseline conditions for assessing future changes if restoration occurs. The second component of this study was to collect water-quality and habitat data, filling information gaps. This information will permit a better understanding of the relation between physical habitat and nutrient conditions and changes that may result from salmon restoration. We collected data in the fall of 1997 and found that the concentrations of nitrogen and phosphorous were generally low, with most samples having concentrations below detection limits. Detectable concentrations of nitrogen were associated with sites in the lower reach of the Elwha River, whereas the few detections of phosphorus were at sites throughout the basin. Nutrient data indicate that the Elwha River and its tributaries are oligotrophic. Results of the stream classification indicated that most of the habitat that would be usable by salmon is found in the mainstem of the Elwha River due to natural gradient barriers at the lower end of most tributaries. Habitat is diverse in the mainstem due to large woody debris accumulations and the existence of secondary channels. We concluded that restoring salmon runs to the Elwha River system will affect the ecosystem profoundly. Decaying carcasses of migrating salmon will be the source of large quantities of nutrients to the Elwha River. The complex instream habitat of the mainstem will enhance cycling of these nutrients because carcasses will be retained long enough to be assimilated thereby increasing primary and secondary production, size of immature salmonids, and overall higher salmon recruitment.

Washington↗