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Past projects
In addition to our long-term monitoring programs, we conduct various studies to evaluate stormwater treatment options, assess contaminants in the environment (e.g., water, sediment, air) and support projects to evaluate contaminants in King County stormwater, wastewater, and solid waste. We also develop modeling tools to assist in watershed-scale evaluations of pollutants in King County.
Chemicals of emerging concern (CECs) studies
Chemicals of emerging concern, or CECs, are poorly regulated or unregulated pollutants that have been detected in our environment and research is showing negative effects on people, wildlife, or aquatic life. CECs come from many sources including pharmaceuticals, common household products, vehicles, and industry. King County is working to identify, track and mitigate CECs through a variety of monitoring projects, research, policy, and public awareness campaigns.
Recent King County projects involving CECs include:
- CEC presence and concentrations in marine and freshwater fish across King County (report)
- Identifying CECs present in salmon spawning and rearing streams (project webpage)
- CEC presence, concentrations and potential impacts on food crops after irrigation with Sammamish Valley recycled water and surface water (project webpage)
- Monitoring for CECs in surface waters to inform combined sewer overflow (CSO) projects (report)
PFAS investigations
PFAS are a class of human-made chemicals used in a wide range of consumer and industrial products including food packaging, cosmetics, cookware, carpets, firefighting foam, and more. PFAS, also known as “forever chemicals”, pose a risk to human health and potentially impact wildlife and plants in the environment.
King County measures PFAS in our wastewater and landfill systems. PFAS have also been part of some other CEC studies, including the chemicals of emerging concern studies above.
- Evaluating PFAS in King County wastewater, biosolids, and landfill leachate (project webpage)
6PPD-quinone (6PPDQ) studies
6PPD-quinone (6PPDQ) was recently discovered and is extremely toxic to salmon, especially coho. 6PPDQ comes from a rubber additive, 6PPD, that is primarily used for preventing tire rubber degradation. 6PPD has been used in all vehicle tires for decades. As tires wear down and their particles are deposited on roadways, rain washes toxic 6PPDQ into nearby waterways where it kills Coho salmon and potentially impacts other species.
We have been investigating this CEC in stormwater and streams through various projects, including:
- Exploring sampling methods and developing a 6PPDQ monitoring program in streams (project plan)
- Modeling 6PPDQ hotspots and prioritizing roads for treatment (factsheet; model report; modeling plan)
- BMP effectiveness studies:
- Effectiveness of stormwater wet ponds and ditches for treating 6PPDQ (project webpage)
- Field testing effectiveness of high performance bioretention soil mixes (HPBSM) in removing 6PPDQ and PFAS from stormwater (project webpage)
- Testing removal of 6PPDQ using HPBSM blends and effect on Coho salmon mortality (project plan; final report)
Watch our video on 6PPDQ and the steps we're taking to address it.
Water Quality Benefits Evaluation (WQBE)
King County is committed to investing billions of dollars in water quality improvements in the next decade. The Water Quality Benefits Evaluation (WQBE) Toolkit provides consistent, science-based methods for assessing how actions improve water quality outcomes, which is one consideration for King County planning and prioritization processes.
Check out the WQBE program webpage to learn more
Pollution tracing studies
Contaminants from multiple sources enter water via numerous pathways, resulting in environmental pollution from either a few major sources or accumulation from many inputs. These contaminants often originate from specific industrial activities, including both current and historic industries that operated before modern environmental regulations were established. They can also come from stormwater runoff carrying contaminants from across the broader watershed downstream.
King County, particularly along the Duwamish River and Puget Sound, has experienced extensive industrial activity over many decades and currently faces challenges from ongoing urbanization. By identifying contaminant sources, King County can prioritize source control and cleanup efforts to improve water quality for people and the environment. Some of the projects we have worked on to identify contaminant sources include:
- A series of projects evaluating the major pollutants entering the Lower Duwamish waterway to identify primary sources, and to determine how to reduce pollutant contributions to the Duwamish River (projects webpage)
- Measuring and modeling the ways in which contaminants get into Lake Washington and into fish (project webpage)
- Review of PCB source tracing programs in Washington and Oregon to summarize and compare/contrast source tracing approaches (report)
Stormwater management effectiveness projects
We have participated in several studies evaluating the effectiveness of various stormwater treatment or mitigation measures for contaminants. These projects are part of the Stormwater Action Monitoring program through the Western Washington Stormwater Work Group. This program is administered by Washington Department of Ecology and funds key projects for assessing actions taken under the stormwater discharge permits for what’s working and what isn’t.
Learn more about SAM effectiveness studies at the Washington Department of Ecology website.
- Evaluating the effectiveness of crushed oyster shells treating stormwater runoff (project webpage, factsheet, report, project plan)
- Capture and treatment of polychlorinated biphenyls (PCBs) using bioretention mesocosms (factsheet, report, project plan)
- Developing and testing treatment effectiveness of several alternative bioretention soil mix (BSM) blends (factsheet, report, project plan)
- Collecting, assembling and analyzing local government catch basin data to predict future maintenance needs (factsheet, report)
- Evaluating how effectively a large improvement project treats stormwater at a regional water detention facility in Federal Way (project webpage, factsheet, report, project plan)
- Effectiveness of stormwater treatment facilities along a state route in Shoreline (factsheet, report, project plan)