Willamette River Basin Water Quality Study Background

Overview

In 1991, the Oregon Department of Environmental Quality (DEQ) embarked on a cooperatively funded study of the water quality of the Willamette River and its tributaries. The study focuses on pollution types, sources and their effect on the river's health and the basin's ecosystem. This will provide DEQ with the information needed to protect the many important uses of the river. During the four-year study, which will be completed in 1995, DEQ will be working jointly with the United States Geological Survey (USGS) and technical consultants to thoroughly study the hydrology, chemistry, and aquatic biology of the Willamette.

Funding for the study has come from the Oregon Legislature, the Association of Clean Water Agencies, USGS, pulp-and-paper companies in the basin, and Associated Oregon Industries. Funding for the first phase was $1.275 million; an additional $1.2 million has been allocated to complete the study.

Focus of the Study

  Dissolved Oxygen:

The study will examine the effects of changes in levels of dissolved oxygen on the river's ecosystems. If oxygen levels are too low, fish and other aquatic life will suffer. The decay of large amounts of algae and organic matter can consume so much oxygen that fish will suffocate.

  Toxics:

DEQ and USGS are collecting and analyzing data on toxics such as pesticides, heavy metals, and dioxin to determine the types and amounts present.

  Point Sources:

Point sources are specific discharges of wastewater which often enter the river from pipes. These discharges are being monitored to determine the types and amounts of pollutants present and the impacts on water quality.

  Nonpoint Sources:

Pollutants from nonpoint sources enter the river from wider areas than point sources. Examples include runoff from agricultural land, streets, parking lots, storm drains, and construction sites. The study will begin to evaluate the effects of these nonpoint sources on water quality.

  Bacteria:

The study will provide information on existing levels of bacteria in the basin. Sources include sewage treatment plant bypasses, combined sewer overflows, and nonpoint sources such as agricultural activities.

  Ecological Conditions:

The study will examine the relationships between aquatic life, habitat, and water quality. The information will be used to develop biologically based water quality standards.

Phase One Findings (Preliminary) 1991-1993

Information obtained during the first phase of the study has provided clues about potential problems and has allowed DEQ to develop computer models to assist with further research. Preliminary findings indicate that:

About 70 to 80 percent of pollution enters the river via nonpoint sources, particularly from agricultural activity. About 90 percent of the nonpoint source discharge occurs during the rainy season.

The biological health of the mainstem of the river is good in the far upper reaches above Eugene, fair in the middle reaches between Eugene and Wilsonville, and poor from Wilsonville through Portland.

Based on a sampling of Juvenile Northern Squawfish, it appears that about 2 to 3 percent of the fish in the river have skeletal abnormalities. However, this finding may not be biologically significant. In other words, this amount of change may be normal for this type of fish. Near Newberg, abnormalities were found in about 13 percent of the fish sampled. Preliminary data suggests that one of the causes of the abnormalities may be cross-breeding between species.

A computer model developed for the study will be used to predict levels and movement of toxics in water and sediment. Models are also being used to study changes in concentrations of dissolved oxygen, and levels of nutrients in the river. Preliminary results indicate that dissolved oxygen levels were below normal in the lower Willamette below Wilsonville. Fish communities were evaluated at 19 sites. Results showed that the number of species present at each site decreased the further downstream the samples were taken.

Phase Two 1993-1995

The second phase of the study is based on the findings from the first phase.

The distribution and movement of herbicides, pesticides, and other toxics in water and suspended sediments is being examined in conjunction with USGS surveys. Toxics in effluent is also being studied. Studies of dissolved oxygen, nutrients, and algae will continue, along with surveys of pollutants from major and minor point sources.

A sub-basin will be sampled and evaluated to determine the nature and extent of nonpoint source pollution from agricultural lands.

Biological monitoring, including follow-up monitoring of skeletal abnormalities, will be continued.

After the study is completed DEQ will use the information gained from the study to direct pollution control efforts in the Willamette Basin. The study will also serve as a base for future monitoring and research efforts.

Public Involvement

DEQ will provide opportunities for public involvement with the study. The Willamette River Basin Water Quality Technical Steering Advisory Committee meets every first Wednesday of each month.

If you would like to receive notices of meetings or workshops, please contact the Willamette River Basin Study Coordinator, DEQ, 811 SW Sixth Avenue, Portland, Oregon, 97204. People may call (503) 229-5279 or toll free inside Oregon: 1-800-452-4011. People with hearing impairments may call DEQ's TTY number at (503) 229-6993.

Accessibility Information

This publication is available in alternate format by calling DEQ Public Affairs at (503) 229-5766 or toll free in Oregon 1-800-452-4011. People with hearing impairments may call DEQ's TTY at (503) 229-6993.

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