Logjams make the Cedar River unsafe for recreation, but they’re great for fish

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A cottonwood spans the Cedar River, one of many downed trees that have led to the river’s closure.

The King County Sheriff’s Office announced earlier this month that a portion of the Cedar River is closed to all in-river recreational use for the second season in a row due to numerous logjams, downed trees, hanging limbs and other blockages.

The river is closed from river mile 4.5 to river mile 13.5, a nine-mile stretch from Renton to Maple Valley. Twelve blockages – nine of them serious – make the river too dangerous for recreation, according to the Sheriff’s Office. The blockages are similar in number and severity to last year – and all are due to naturally occurring processes.

John Koon, a senior engineer in the County’s Rivers Section, recently walked the banks of the Cedar and could see why law enforcement made the decision. He saw two punctured rafts wrapped around a logjam, a sobering sight. John has been monitoring rivers in King County for more than two decades. “I don’t remember the Cedar ever having so many hazards.”

But there’s an important twist in this ongoing discussion over the state of the Cedar River. The strainers, spanners and logjams may be bad for those who want to float the Cedar, but they’re excellent for fish, including two runs – fall chinook and steelhead – that are listed as threatened under the Endangered Species Act (ESA) and protected under tribal treaty rights.

Adding to the situation is the unique nature of the Cedar, a river that brings this dilemma into focus like no other in the region. The Cedar is just the right size to be closed by a spanner and just slow enough for some of those spanners to remain in place. It’s near an urban center – and thus to people who want recreate in it, including boaters, anglers and those who like to float the river. And all that wood provides invaluable habitat to ESA-listed fish, fish that the state and tribes co-manage with an eye towards ensuring their survival and resilience.

“We’re working right now with the tribes, the state and other jurisdictions to try to figure out the best path forward with the Cedar. But there are no good models,” said Josh Baldi, director of the Water and Land Resources Division.

“How do you make a river safe for recreationalists while improving habitat for fish? We know how to do this when designing restoration projects, but it’s far trickier with natural wood recruitment. This is largely unchartered terrain.”

So why does wood in a river matter so much? Large pieces of wood trap other pieces of wood, creating complex habitat that supports salmon at several stages in their life cycle, explains Sarah McCarthy, a senior ecologist in the County’s Water and Land Resources Division.

Wood, for instance, retains gravel, which is needed for spawning. It encourages riverbed scour, which in turn creates pools where salmon can rest, find deep, cool refuge and hide from predators. Logjams slow down the flow and sometimes split a channel, creating new channels and backwaters critical to healthy salmon runs. Wood is also the basis for an aquatic food web – invertebrates live in the downed trees and logs and occasionally fall into the river, where they’re snatched up by hungry fish.

“The research is clear that wood in rivers and streams improves habitat quality,” Sarah said.

Western Washington’s rivers used to be filled with wood. But over the course of the past century or so, much of that wood was removed or prevented from falling into rivers – the result of logging and agricultural practices, navigational improvements and flood control efforts.

Those actions came with a cost. The removal of wood led to the destruction of salmon habitat and added to the steady decline of salmon in the Pacific Northwest. Today, 17 distinct salmon populations are listed as threatened or endangered under the ESA in Washington. And while wood removal was seen as a way to provide flood protection, in many instances it made the situation worse – causing faster, more unconstrained flows, erosion and channelization.

Government agencies, including King County, are now seeking a new path, trying to balance all of these competing forces in support of rivers that are healthy and resilient and that are good for both people and fish. As a result, the County routinely incorporates wood into both restoration and flood control projects, using the best science and engineering practices to do so and keeping stakeholders – including river safety advocates and recreationalists – informed throughout the process.

Earlier this month, project managers in the Water and Land Resources Division held two public meetings to discuss several current projects that will use placed wood either to improve habitat or provide flood protection.

As for the Cedar, where naturally occurring wood – not wood used in restoration or flood control projects – is making in-water recreation dangerous, Kate Akyuz, a senior environmental scientist in the Rivers Section, is working with the Sheriff’s Office, state officials, tribal biologists and others to determine a course that makes sense. It’s possible, for instance, that some of the wood could be shifted or removed, she said, noting that doing so would require the County to mitigate for that removal by creating salmon habitat elsewhere.

Josh attended one of the recent public meetings about large wood where he discussed his own love of river rafting as well as the environmental challenges at a place like the Cedar River.

“We have a lot of needs we’re trying to balance in a river that is important to many different constituents,” he said after the meeting. “Our goal is to approach this issue using both solid science and thoughtful public policy and to do what’s right for both people and fish.”

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This tree spans the Cedar at river mile 9.7.