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2023 State of the McKenzie Watershed: Overall Water Quality Remains Excellent Despite Major Challenges

March 07, 2024 Adam Spencer, Communications Specialist

Koosah Falls of the McKenzie River

EWEB State of the McKenzie Watershed Report 2023: Overall Water Quality Remains Excellent Despite Major Challenges

EWEB’s Drinking Water Source Protection (DWSP) team says the McKenzie River continues to be an excellent source for drinking water.

In its 2023 State of the McKenzie Watershed Report, the DWSP team shares the results of its water quality testing from dozens of locations throughout the watershed. Routine sampling proves the baseline water quality of the McKenzie River is consistently outstanding, with cold, clear water and very low levels of impurities.

The report also shows that growing threats to the watershed’s health are more impactful than in previous years, but only for short periods of time following heavy rains that wash contaminants into waterways.

“We have abundant, clean water, and one of the healthiest river ecosystems for native salmon in the Willamette Basin,” said EWEB Water Resources Supervisor Susan Fricke. “But last year we saw several storms have a big impact on the McKenzie and its tributaries, so we’ll continue to monitor, engage and act in collaboration with our partners.”

Intense storms flush contaminants

The McKenzie provides some of the best drinking water in the world for 200,000 people in the Eugene area thanks to its unique geology, wet, Pacific Northwest temperate climate, and relatively low population density.

Its waters pass through a volcanic landscape that filters sediments and keeps snowmelt nearly ice-cold underground before the McKenzie emerges at Clear Lake.

Pacific Northwest rains sustain forests that cover 90% of the McKenzie Basin. Trees, roots, fungi, and healthy soil biota add another massive system to clean our water.

The watershed’s natural filters require regular precipitation and time to process it – and climate change is disrupting the water cycle. Last year’s total precipitation was lower than the 30-year average.

Storms have always caused water quality impacts. Heavy rains carry materials into the waterways from across the landscape – whether running over forest floors or pavement.

Several storms last year produced greater-than-usual water quality impacts for the McKenzie watershed. Rains were also irregular, with heavy storms ending months-long droughts.

The DWSP team identified two principal causes of the temporary spikes in contamination events are the impacts of the large wildfires of the past few years and increasing levels of pollution from suburban areas.

“We’re seeing exactly what we expected following the Holiday Farm Fire, in terms of water quality impacts,” Fricke said. “We’re in the three-to-five-year window after a stand-replacing fire when the death of root structures peaks, leading to landslides that can foul up waterways. We’ve actually had less of a water quality impact from erosion than we originally anticipated.”

Fricke also emphasized that EWEB will continue to work with partners in Springfield, including the City of Springfield and the Urban Waters and Wildlife program, to address the water quality hits from urban runoff detected in stormwater channels in East Springfield.

“The contamination spikes in the stormwater channels are a yellow flag for us,” Fricke said. “We’ll increase our testing in those waterways, including doing some DNA tracking and bracketing to collect samples above and below our established sampling points to identify the source of those contaminants so we can do more outreach with our partners and work with the community to reduce those inputs.”

Wildfire impacts to water quality

The report provides further details on how the recent wildfires are affecting water quality.

The tributaries most impacted by the Holiday Farm Fire registered the highest amounts of turbidity, total suspended solids (TSS), total metal concentrations and nutrients compared to samples from the rest of the watershed.

Turbidity is measured in FNU, which quantifies the cloudiness of debris in a water sample by how much light it disrupts. The McKenzie River is usually very clear, with turbidity levels near Vida typically below 2 FNU. Since the Holiday Farm Fire, there have been 8 events exceeding 50 FNU, including during storms in early November and early December of 2023.

Another metric weighs the actual mass of suspended (TSS) and dissolved solids (TDS). During a December storm event in 2023, the team reported TSS in the mainstem of the McKenzie River at the highest levels observed over the past 15 years. Levels were higher than a December 2020 storm after the Holiday Farm Fire.

The DWSP team also monitors 19 metals in the watershed, which originate from a variety of natural and anthropogenic sources. Concentrations of heavy metals are rarely detectable (above the reporting limit) in the mainstem McKenzie River. Heavy metals, such as cadmium and lead, can increase the risk for a variety of short- and long-term health effects if consumed in high concentrations.

Marten Creek

Marten Creek, which lies entirely within the Holiday Farm Fire footprint, registered the highest total metal concentrations for 15 of the 19 metals evaluated. Gate Creek – also heavily burned – reported the highest total mercury concentration.

The team also found in Marten Creek the highest levels of nitrate and phosphorous – nutrients that can stimulate harmful algal blooms and disrupt ecosystem functions.

“When there’s higher levels of materials in the water, our team at the Hayden Bridge Water Treatment Facility has to work harder to filter it out. It means more time, more resources, and more expenses than we usually apply to the relatively-clean McKenzie River,” Fricke explained. “But so far everything we’ve seen coming off the post-fire landscapes is well within water quality compliance levels and treatable with our modern facilities.”

To counter the threats from wildfires, the report highlights the ongoing efforts of the Pure Water Partners and the large-scale restoration projects that are bolstering the McKenzie’s natural defenses throughout the watershed. 

Opportunity to reduce pollution from urban runoff

Although the McKenzie watershed has low population density, rains wash contamination from suburban areas into waterways in East Springfield. EWEB monitors five stormwater channels that collect pollution from roadways, sidewalks, driveways, rooftops, and parking lots.

While stormwater channel flows are considered very small relative to McKenzie River flows, they often register the highest levels of bacteria and organic compounds, such as household chemicals and pesticides.

Last year’s August and November storms resulted in several high recordings of E. coli, a bacteria found in human and animal waste.

E. coli detections in the stormwater channels are likely due to pet waste left on sidewalks, parks, trails, and lawns

“The bad news is there’s untreated waste entering the water. The good news is we have the tools to figure out where it’s coming from and we can work with the community to manage the problem,” Fricke said.

EWEB is already in compliance with proposed new regulations on PFAS

In 2023, the Environmental Protection Agency announced proposals to adopt new regulations for Per- and Polyfluoroalkyl Substances (PFAS) chemicals. EWEB began testing for these “forever chemicals” in finished drinking water starting 2013 and have never detected PFAS in finished drinking water nor at the filtration plant intake on the McKenzie River.

While no PFAs compounds were detected in the McKenzie River or its major tributaries in 2023, the DWSP detected PFAs in the stormwater channels of East Springfield. To identify the source and better contain these contaminants, the team is planning additional PFAS testing in these stormwater channels.

As PFAs chemicals are mainly used for water-proofing and found in household items like stain-resistant carpets, waterproof clothing and non-stick cookware, it is not surprising to find them associated with the more densely populated parts of the watershed.

Partnering to improve long-term resiliency

EWEB’s DWSP team monitors and protects water quality, implements proactive strategies that reduce water treatment costs, and promotes public awareness and stewardship through targeted actions and programs.

EWEB is part of a network of dozens of governmental, private, and non-profit organizations devoted to protecting the McKenzie for generations to come.

By leveraging customer water rates, EWEB can obtain grants to manage the watershed as part of our drinking water infrastructure. EWEB and our partners’ programs fund incentives to reduce human impacts, help the watershed recover from wildfires, and restore the river’s natural resiliency.

To fight bacterial contamination, EWEB has a long-running program to help pay for septic maintenance for upriver community members.

EWEB is also partnering with Lane County, Business Oregon, the Department of Environmental Quality, and others to distribute up to $3 million in septic system assistance grant funds from the American Rescue Plan Act. Septic grant funding needs to be allocated by the end of the year, so interested McKenzie landowners upstream of Hayden Bridge should visit for more information.

EWEB is also a core member of the Pure Water Partners (PWP) Program, a collaboration of the McKenzie Watershed Council, McKenzie River Trust, Upper Willamette Soil & Water Conservation District, and other local organizations that work with landowners to protect and restore lands along the river.

PWP provides technical assistance around naturescaping and Firewise landscaping practices to increase native plants, reduce chemical use, protect water quality and increase resilience to wildfire.

EWEB has contributed nearly $11M to PWP wildfire recovery efforts to replant riparian forests, reduce fuels, monitor invasive species, mitigate erosion, and implement large floodplain restoration projects.

In 2023, EWEB celebrated the completion of the Finn Rock Reach Floodplain Enhancement Project with the McKenzie River Trust and Willamette National Forest. The project restored 400 acres of wetlands, creating space to slow floodwaters and allow contaminants to drop out rather than flow downstream.

Finn Rock Reach floodplain

The strategy is to restore the McKenzie’s natural water quality maintenance regimes. EWEB is partnering with the McKenzie Watershed Council to create a similar natural floodplain filter at Quartz Creek – another heavily impacted tributary.

“The large-scale restoration work to reset floodplains is incredible. Thanks to our partnerships with public and private landowners, we can improve conditions from hillslope to hillslope and maximize landscape potential across the valley,” Fricke said.