If you have been wondering if the Willamette River Basin is safe for swimming, the overall answer is yes. However, whether or not the river is pollutant-free, requires more of a deeper dive.
This week, the Oregon Department of Environmental Quality released the Willamette Basin Toxics Monitoring Summary. It combines water, sediment and tissue sampling results from DEQ’s Toxics Monitoring Program in the Willamette River Basin from 2008 to 2010 and 2016. The goals of the assessment are as follow:
- Get a snapshot of pollutants in the Willamette River Basin to help understand trends
- Use the data to identify potential sources
- Make the information available to the public
- Work with internal DEQ groups, community groups and those living in Oregon to identify opportunities to reduce the pollutants
Between the two studies included in the summary, 238 samples were collected from 47 monitoring locations. They were analyzed for various chemical groups, including current-use and legacy pesticides, consumer-use products, combustion by-products, dioxins and furans, flame retardants, industrial chemicals, PCBs and metals. The monitoring locations were divided into three sub-basins (Lower, Mid and Upper) to give attention to the diverse regions of the Willamette Basin.
In 2016, water samples were collected three times (spring, summer and fall), while sediment and tissue samples were collected once. Also, tissue samples, crayfish and mussels were collected to help gain an accurate picture of the environment at each sampling location.
Key findings in the sub-basins include:
- Legacy pesticide concentrations remain high when compared to concentrations in the 2008-2010 study. Legacy pesticides are banned from use, indicating residual sources in the basin.
- Mercury found in crayfish at the Willamette River at the St. John’s Bridge location exceeded DEQ’s human health criterion. The criterion assumes a consumption rate of 175 grams per day. This area is part of the Portland Harbor Superfund site.
- Mercury found in crayfish at the Willamette River at Marion St. location exceeded DEQ’s human health criterion.
- Concentrations of DDT exceeded its sediment benchmark across the Mid-Willamette basin. Concentrations at this level are not expected to adversely affect human health.
- High concentrations of the herbicide diuron detected in water from Lake Creek do not pose a risk to human health.
- DEQ detected 152 chemicals in sediment collected downstream from a stormwater outfall near Maurie Jacobs Park. The detected chemicals were not found at concentrations that pose a risk to park users.
Based on the results of this study, 11 monitoring locations were selected to become part of the Toxics Monitoring Program’s trend network. It consists of 60 monitoring sites across the state, representing each major river basin, as well as locations with elevated concentrations of chemicals of concern and background locations. DEQ’s Laboratory will collect water samples at these sites three times annually. Sediment and tissue samples will be collected once annually. All sampling depends on Lab resources and approval to travel during the pandemic.
Additionally, the results from the summary will be used to inform several existing DEQ efforts, including the DEQ Integrated Toxics Reduction Strategy, the Integrated 303 (b) and (d) Reports for the federal Clean Water Act, and Total Maximum Daily Load, National Pollution Discharge Elimination System and stormwater permitting and regulatory programs. This will ensure that the waters of the Willamette River Basin continue to meet water quality standards and are safe places for people to recreate.
— Dan Brown, water quality assessment specialist