Blog topics » Habitat restoration

Category: Habitat restoration

Governor’s renewed salmon strategy faces decisive period in the current Legislature

State legislation designed to enhance salmon habitat by requiring protective buffers along streams has been set aside pending further discussions over the coming year. Meanwhile, several other salmon-protection measures proposed by the governor could move forward with decisive funding from the Legislature.

Washington Capitol, Olympia

The buffer bill (HB 1838), named the Lorraine Loomis Act, would prohibit degradation of streamside habitat while encouraging restoration within prescribed “riparian management zones” on both public and private lands. Such requirements would apply to farmland, areas destined for development and even properties undergoing redevelopment. The bill is part of Gov. Jay Inslee’s wide-ranging “Salmon Strategy Update” (PDF 1.4 mb), which was proposed with a price tag of $187 million for the first year, according to a policy brief (PDF 1.4 mb) on the topic.
Maintaining vegetation — including tall trees — along streams helps to shade the water and avoid temperatures that can be debilitating or lethal to fish. (See my story in the Encyclopedia of Puget Sound.) Vegetated buffers also can filter out pollution from upstream areas, provide food and shelter for fish and wildlife, and help to mitigate high and low streamflows.
During recent hearings, numerous farmers and representatives of agricultural groups complained that they had not been consulted before the buffer bill was dropped on them. They said the stream-buffer requirements could take a severe financial toll on their operations, even if they were provided with some compensation for production losses and grants for restoration, as proposed in the bill.
Faced with this powerful opposition, the bill never came up for a vote in the only committee where a hearing was held: the House Rural Development, Agriculture and Natural Resources Committee. (Videos available via TVW.)
On the Senate side, the handwriting was already on the wall. On Feb. 3, the Senate Agriculture, Water, Natural Resources and Parks Committee held a work session on the governor’s salmon strategy. Sen. Kevin Van De Wege, the committee’s chairman, asked the governor’s staffers if they had done any public polling to measure support for the buffers bill.
“I think, to be honest with you, the way the bill was introduced, I don’t think it has passed the court of public opinion,” Van De Wege said. “I would be worried about doing a heavy lift like that to have it simply overturned by referendum — which I think would be likely the way the bill was introduced.”
Jennifer Hennessey, the governor’s policy adviser on environment, water and ocean health, said she was unaware of any polls on the issue. The legislation resulted from discussions about the needs of salmon with Washington’s native tribes, she noted.
“We certainly recognize that there is more work that needs to be done to talk about the needs of riparian habitat with a variety of stakeholders and the way we get to the end goal of improving habitat for salmon,” Hennessey said.
Other provisions
While legal mandates for buffers are off the table for the current legislative session, other aspects of the bill could be accomplished with funding in the supplemental budget, a draft of which should soon be made public.

Under consideration for funding is a process to facilitate a “diverse stakeholder group” that would discuss buffers as part of a legislative package for the next session, according to Sen. Christine Rolfes, D-Bainbridge Island, who chairs the Senate Ways and Means Committee.
Other programs described within the bill could be started or enhanced with dedicated funding, she said. They could include high-tech mapping to locate important streamside habitat, an analysis to identify high-priority areas for restoration, and a program to build up a nursery stock of trees for extensive planting efforts. Appropriations for these efforts would be directed to the state departments of Ecology and Fish and Wildlife.
Protecting salmon streams with vegetated buffers is an urgent need in the effort to restore salmon populations, as climate change increases its impact, said Dave Herrera, fisheries and wildlife policy director for the Skokomish Tribe and vice chairman of the Puget Sound Salmon Recovery Council.
“The tribes have been talking about the need for adequate riparian buffers for a long time, not just on agricultural land but for all lands with salmon streams,” he said. In 2019, during the annual Centennial Accord discussions, Gov. Inslee made a commitment to the tribes to establish statewide buffer standards. (See the June 4, 2020, column by the late tribal leader Lorraine Loomis, for whom the legislation is named.)
Representatives of the Washington Department of Agriculture and Washington Conservation Commission were involved in meetings about the buffer standards, Herrera said. “I was surprised to hear that the communities served by those agencies were not aware.”
Herrera said he is now getting a lesson about the pace of the legislative process and remains optimistic that people will come to understand the needs of salmon in time to save them. Failure of the Lorraine Loomis Act during this legislative session is a setback, he said, but things are at least moving forward.
“To his credit, the governor stepped up and developed a bill that got introduced, and it is setting up a conversation that we have been needing for a long time,” he said. “People need to understand the urgency. It is getting to the point where we have to ask ourselves if we really want to recover salmon or if it is just too hard for us to do.”
Buffers defined
As proposed, salmon streams would be mapped with riparian management zones to identify the width of required buffers. That width relates to the area’s 200-year “site potential tree height” — the height that an average tree would reach in 200 years in a given location. Thus the buffer can range from 100 to 240 feet from the edge of a stream, depending on soils, rainfall, topography and other factors. These are the standards recommended in a report called “Riparian Ecosystems, Volume 2, Management Recommendations” by the Department of Fish and Wildlife.
Under proposed legislation, now on hold, salmon habitat would be protected by creating a buffer zone beyond the immediate stream channel, as recommended in “Riparian Ecosystems, Volume 2.” (Click on image to download document.)

Using tree height to establish the buffer width is partially based on the idea that trees falling into a stream add critical structure, helping to create pools and riffles needed for safe salmon migration and spawning. The idea grew out of findings from a 1993 report by the multi-agency federal Forest Ecosystem Management Assessment Team (PDF 68.5 mb), or FEMAT.
Some people testifying against the proposed buffers bill say the tree-height approach lacks an adequate scientific foundation to become a requirement in state law. No doubt this will be a major topic of discussion during the anticipated stakeholders meetings, which are likely to include representatives of farmers, developers, local governments, businesses, environmental interests and more. By the way, forestland that is subject to the Washington Forest Protection Act must comply with separate buffer regulations, which undergo changes based on emerging science.
As written into the proposed legislation, the required buffers on private land could be reduced if the protected area takes up more than half the parcel.
Voluntary stewardship
Several people who testified on the buffers bill worried that it would supplant a voluntary stewardship program in which farmers work with local government experts to establish reasonable buffers protective of salmon habitat without overly affecting their livelihood.
“Voluntary programs do work when they are sufficiently funded, but the state has not provided enough funding,” said Tom Salzer, executive director of the Washington Association of Conservation Districts, which represents 45 local districts.
Over the last three biennia, the Washington Conservation Commission requested nearly $20 million for the Conservation Reserve Enhancement Program, Salzer testified during the first hearing on the bill. That program provides $3 in federal funds for every $1 in state funding for habitat protection and improvement. The Legislature provided less than half the requested amount, losing out on nearly $30 million in habitat restoration money, he said.
“We believe that if sufficient funding had been provided for voluntary conservation, today there would be no perceived need for this legislation, he added.
The Voluntary Stewardship Program, created in 2011, enlisted 27 of the 49 counties before a cutoff deadline in 2012. A new bill in this year’s Legislature (HB 1856) would allow any other county to join by July 1, 2023. The main concern expressed during hearings on the bill was that each local program would receive even less money if the Legislature failed to increase overall funding. The bill is now up for a vote on the House floor.
Budget decisions
Beyond the proposed buffer requirements now on hold along with a proposal for $100 million in grants for affected property owners, the governor’s revised salmon strategy includes the following elements:

  • Riparian protection mapping: Buffer widths and existing conditions could be identified for streams throughout the state. WDFW, $4.7 million.
  • Plant propagation: Public and private nurseries could be funded to grow trees and plants available for buffer restoration. State Conservation Commission, $1.3 million.
  • Toxic tires: The search continues to identify solutions to a deadly chemical associated with tires that washes into stormwater, gets into streams and kills coho salmon, with impairment to other species. Ideas include filtering stormwater and identifying alternative chemicals. Department of Ecology, $2.7 million.
  • Stormwater: Grants are proposed for increasing local stormwater capacity, $4 million, and encouraging public-private stormwater partnerships, $1 million, both through the Department of Ecology.
  • Streamflow restoration: “Green infrastructure” projects can capture and store excess water during heavy rainfall events and then release the water when streamflows drop to critically low levels during dry periods. Benefits include reduced pollution and cooler water in streams. Ecology, $5.5 million.
  • Fish passage programs: Efforts to remove or replace culverts and other barriers to salmon migration could be increased by prioritizing the needs and drafting new state rules to address the problem. WDFW, $654,000.
  • Harvest monitoring and enforcement: WDFW could increase its ability to protect salmon during commercial and sport fisheries with increased enforcement, $1.2 million; environmental prosecution, $852,000; and fisheries planning, $842,000. A license buy-back program could reduce gillnets on the Columbia River, $16.7 million.
  • Hatchery programs: An evaluation of hatchery programs in Puget Sound by WDFW could help to improve survival rates of hatchery fish and reduce impacts on wild salmon, $4.3 million. Also proposed is a new hatchery on the Deschutes River in South Puget Sound, $2.2 million.
  • Hydropower: State officials could increase their collaborative work on the Columbia and Snake River dam issues during federal relicensing to ensure state interests are met in protecting salmon and water quality, $1.1 million. A Snake River mitigation study will help determine if the removal of four dams is a feasible and reasonable solution, $375,000.
  • Skagit River protection: The Department of Commerce will seek to protect the upper Skagit from future development, $4.5 million.
  • Science and monitoring: WDFW could increase monitoring of adult and juvenile salmon migration to evaluate habitat function and salmon productivity, $2.4 million. Other studies could focus on forage fish populations, which are important to salmon and many other species, $721,000.
  • Salmon recovery plans: Puget Sound Partnership could coordinate the update to salmon recovery plans in the Puget Sound region, including support to local governments that must implement some aspects of the plan, $2.6 million.

Behind-the-scenes budget negotiations over salmon funding have been ongoing this week, with decisions to affect funding for these proposed projects that could be started this year.

Understanding the cold-water needs of salmon and helping them to survive

Salmon need cold water. This general statement is something I’ve been hearing since I first began reporting on these amazing migrating fish years ago. Cold water is a fact of life for salmon, known for their long travels up and down streams, out to saltwater and back. But colder is not always better.
Questions about why salmon need cold water and how their habitat might grow too warm or too cold led me into an in-depth reporting project. I ended up talking to some of the leading experts on the subject of stream temperature. Thanks to their fascinating research, I learned that temperature and food supply go hand-in-hand to dictate salmon metabolism, growth and survival. You can read my report, “Taking the Temperature of Salmon,” in the Encyclopedia of Puget Sound.

Middle Fork of the Snoqualmie River, near Mount Si trailhead
Photo: Christopher Dunagan

Later in this blog post, I will touch on some new developments regarding temperature and stream conditions — including Gov. Jay Inslee’s latest initiative to help salmon by proposing new laws and regulations along with $187 million in next year’s budget request.
In the Northwest, we almost never need to worry that salmon streams will get too cold. Logging, farming and development have removed large amounts of streamside vegetation, allowing the sun to warm the waters, often to excessive degrees. While sunlight can increase the growth of tiny organisms and boost the food web, higher temperatures also accelerate metabolic rates, increase stress hormones and alter behavioral responses, as I described in my story.
When a section of a stream grows too warm, fish will seek out cooler water, often by swimming upstream to areas cooled by springs or snowmelt. As a change in temperature alters metabolism and behavior, the result can be problems with finding food and with increased threats of predation.
“Anybody who does stream work soon learns that fish are amazing,” Jonny Armstrong, a University of Oregon researcher, told me. “They don’t just accept the habitat they are given; they do all kinds of things to game the system.”
Jonny’s work in Alaska documented how a run of coho salmon moved into cool water to feed on sockeye salmon eggs. After getting their fill, the fish returned to warmer water to digest the food and grow faster.
I’m especially indebted to Aimee Fullerton, who helped me understand a multitude of biological processes related to temperature, as I searched for ways to explain the complex findings. Aimee is a research fishery biologist with NOAA’s Northwest Fisheries Science Center. She has been working in the Snoqualmie River, where temperatures grow warm enough at times to impair the growth and development of salmon and sometimes kill them if they cannot escape into cooler waters.
The prospects of climate change raise concerns about even higher temperatures in the future. Careful temperature measurements, combined with computer modeling, have helped researchers predict future temperature changes. Other experts are developing new strategies for maintaining cooler temperatures to protect salmon, as I outlined in the story.
Just last week, Washington Gov. Jay Inslee announced a new initiative that he will take to the Legislature next year. He hopes to boost salmon populations by improving stream habitat, replacing culverts and other impediments, and cleaning up polluted waters. Inslee also intends to address harvest, hatcheries and hydropower along with critical issues of predation and food availability.
[iframe align=”right” width=”560″ height=”315″ src=”https://www.youtube.com/embed/j92VkN3TZvg”%5D
“There is no time to waste,” the governor said in a news release. “We have a choice between a future with salmon or a future without them. Salmon need immediate and urgent action to ensure their survival. That’s why, for the 2022 legislative session, salmon recovery is a top priority and have both policy and funding to help protect them.”
One of the key ideas that the governor mentioned during his news conference on Tuesday is to build and/or protect streamside corridors based on the height of trees, which provide shade to cool streams. (See video, embedded on this page, at 11:03-14:30.) The riparian corridor is also important in reducing toxic pollutants, bacteria and fine sediments that enter a stream.
The so-called Governor’s Salmon Strategy Update (PDF 1.4 mb) includes provisions for riparian buffers on agricultural lands, which has been a concern of Indian tribes throughout the region. Details have yet to be proposed, but a combination of regulations and financial support are likely.
The latest initiative grew out of the 2019 Centennial Accord meeting between state agencies and tribal salmon experts led by the Northwest Indian Fisheries Commission.
“This is the first time we have seen legislation that would require landowners to protect riparian habitat,” said Dave Herrera, NWIFC commissioner and Skokomish Tribe policy representative who was quoted in a news release. “It is also groundbreaking because it includes incentives for landowners to create and maintain riparian zones, as well as regulatory backstops when compliance isn’t voluntary.”

Next year’s salmon-recovery legislation will be called the Lorraine Loomis Act, named for the late chairwoman of the Northwest Indian Fisheries Commission who promoted cooperative efforts to save salmon. Budget details are included in a policy brief (PDF 1.4 mb) released by the Governor’s Office.
“We know the status quo isn’t working when it comes to salmon recovery,” Lorraine wrote in a column last year. “We know what the science says needs to be done, and we know that we must move forward together.”
On the regulatory front, the federal Clean Water Act calls for standards that protect aquatic life, such as salmon. Where temperatures are not maintained within an approved range, the waters are considered “impaired” — just as they are when bacteria become too numerous or oxygen levels drop too low for the aquatic species of concern.
Although I did not address regulatory issues in my story about temperature, it is worth noting that numerous federal and state clean-water regulations are undergoing changes. Some changes are the result of lawsuits; some follow statutory requirements; and some stem from the coming and going of the Trump administration’s efforts to reduce environmental rules.
For example, the Environmental Protection Agency recently withdrew its approval (PDF 402 kb) for how the Washington Department of Ecology handles high temperatures in certain stream segments that grow naturally warm. The basic idea is that regulatory agencies need not seek out mitigation measures to cool such waters — even in areas too warm for salmon — if it can be shown that high temperatures represent the natural condition of the streams and that humans are not to blame.
The group Northwest Environmental Advocates first brought a lawsuit over such “natural conditions criteria” in Oregon, where NWEA contended that the state was allowing streams to remain dangerously hot by discounting the effects of humans. In this way, the group argued, Oregon was establishing new and higher temperature standards than allowed by existing regulations without going through a public review process. The higher temperatures should be subject to public review and federal oversight, including effects on endangered species, the group said. Federal courts agreed with that reasoning.
Although the Washington Department of Ecology rarely invokes natural conditions criteria for temperature, it must now review its practices and undergo federal oversight where experts believe that the natural condition of a water body would exceed established water-quality standards. Besides temperature, the review will cover criteria for dissolved oxygen. In some areas of Puget Sound, Ecology has determined that numerical water-quality standards would not be met even if no humans were around.
The methods of determining what the water temperature or oxygen level would be in the absence of human activity can become an elaborate exercise involving computer modeling. But Nina Bell, executive director of NWEA, argues that the process is important and should be open to public scrutiny. After all, she said, the outcome can determine whether unhealthy temperatures or oxygen levels persist or are reduced through mitigation efforts.
Other ongoing water-quality matters:

Recovery of Puget Sound species could hinge on better understanding of ecosystems

A recent report from the Puget Sound Partnership helps us understand the difficulty of restoring the Puget Sound ecosystem. What caught my attention in the State of the Sound report was that after 20 years of protecting and restoring streams, wetlands, shorelines and estuaries, we have not increased overall fish and wildlife populations, and some remain in a downward spiral. (Our Water Ways, Nov. 3).
Several reasons have been given for the disappointing findings, including ongoing habitat losses from an increasing human population in the Puget Sound region. Clearly, there is a need to find ways to accommodate growth while protecting the remaining functional habitats.

Click on image to bring up Vital Signs wheel with links to extensive information about indicators, including key messages, strategies, background documents and other resources.
Info: Puget Sound Partnership

At the same time, I would like to focus some attention on the restoration side of the equation. It seems we may not yet understand what it takes to restore habitats in ways that allow the food web to thrive, thus allowing increasing numbers of higher predators, such as birds, salmon and killer whales.
I recently wrote about some bug-seeding experiments underway in several streams that flow through urban areas in Seattle (Encyclopedia of Puget Sound, Oct. 21). For some reason, populations of aquatic insects known to provide food for salmon were not recovered to the degree expected, given efforts to restore the stream channel, remove invasive weeds, plant native vegetation and reduce pollution to improve water quality. As a result, researchers launched a project of transplanting important insects from a healthy stream. So far, results are mixed.
Katherine Lynch, urban creeks biologist for Seattle Public Utilities, points out that restoration projects are often limited in scope and extent.
“The reality,” she told me, “is that when you go in and do restoration work, you are only doing a short reach. These projects (in Seattle) are a way of exploring what works and what doesn’t.”
To restore or improve salmon habitat in a stream, the challenge is to understand what has been broken in a complex interactive system. Factors include water quality, water flow, clean gravel, and the intricate interactions of the food web — from microscopic organisms to large fish, including predators that eat young salmon.
Emily Schwabe, left, and other members of King County’s bug-seeding team transplant rocks with attached invertebrates to Seattle’s Taylor Creek this past August. // Photo: King County

Take water quality, for example. Until recently, nobody knew what was killing adult coho salmon that found their way into urban streams. Scientists tracked the problem to stormwater entering the waterways from roads and highways. Then last year, thanks to advanced analytical tools, researchers were able to identify the killer compound, which comes from a chemical found in tires. Until then, nobody seemed to know anything about this chemical, let alone thinking that tires might have lethal properties. (EoPS, Dec. 3, 2020).
The discovery opened a lot of eyes to questions about how to identify “clean” water and the prospect that unknown chemicals may be causing unidentified problems in waterways throughout Puget Sound and across the country. The tire-related compound has been found to have lesser effects on steelhead and Chinook but no apparent effects on chum or sockeye. Work continues on varieties of species that might be exposed to road runoff, not just in urban areas but practically everywhere.
The discovery that dying coho could be linked to a tire chemical, known as 6PPD, and its deadly oxidation product, 6PPD-quinone, raises even more questions about the sublethal effects of other chemicals not yet identified. Standard water-quality tests cannot capture the toxicity of unknown chemicals in a stream. Even biological tests, such as using aquatic invertebrates (EoPS), may not reveal the toxic effects on vertebrates — such as fish, birds and humans.
Besides water quality, water flow may be a critical ingredient in stream restoration. I’ve been hearing a lot lately about hyporheic flow — the flow through gravel beneath a stream bed — and its effects on temperature (EoPS, Aug. 19) and oxygen supply, even its ability to filter contaminants.
In Seattle’s Thornton Creek, an understanding of hyporheic flow led to an engineered design in which the stream channel was dug out — up to 8 feet in some places — and replaced with gravel, according to Paul Bakke, owner of a firm called The Science of Rivers who monitored the physical functioning of the project. Rocks and logs were lodged in the streambed along with an impermeable barrier that forced the flowing water deep into the underlying gravel. The water plunges down into deep gravel, coming back up and diving down again several times in each of two reconstructed portions of the stream. The gravel helps filter fine sediments from the stream, but the configuration of the channel allows these fines to be washed on downstream during high flows, Paul explained. Organic chemicals in the water adhere to deeper gravel, where large fractions of chemicals are broken down by microbes.
A restored section of Seattle’s Thornton Creek soon after construction in 2014.
Photo: Seattle Public Utilities

A team of researchers affiliated with the Center for Urban Waters in Tacoma evaluated the fate of 83 chemicals moving downstream in Thornton Creek. Included were the toxic tire chemicals. The hyporheic flow path substantially improved water quality, according to the findings published in 2019 in the journal Water Research.
After construction of the hyporheic zone, Paul found that the vertical flow rate in the new gravel was 89 times higher than in the previous streambed, which had been impounded by a heavy sediment load. In fact, the fresh gravel produced a flow rate 17 times higher than in a forested stream in the mountains of Idaho.
The newly engineered stream also included a floodplain, created by removing flood-prone houses from the area. During high flows, sediment-containing water moves from the stream channel into the floodplain, where lower water velocities allow the sediment to settle out. That helps to protect the stream channel from excess sediment.
According to Paul, the key to success was rebuilding the stream by carefully choosing the width and depth of the channel and floodplain. The new configuration balances the forces of erosion and deposition, thus maintaining the channel in a more natural condition. In addition to Paul, the lead channel designer was Mike “Rocky” Hrachovec, owner of Natural Systems Design. For details of the design, check out the article in Research Outreach or the more technical article in the journal Water.
In October 2018, a pair of Chinook salmon spawn in a restored section of Thornton Creek. // Photo from GoPro video: Chapin Pier, Seattle Public Utilities

The ability of the restored sections of Thornton Creek to clean themselves, increase oxygen levels and mediate temperatures has led to a healthier condition, despite the urban setting in North Seattle.
In 2018, four years after construction, a female Chinook salmon swam warily upstream. With a male Chinook standing by, she deposited her eggs, which were quickly fertilized by the male.
“They spawned,” Katherine said. “We had never seen salmon spawn in the project region.”
A lack of funding and the COVID-19 pandemic have prevented further in-person monitoring of salmon movements, but new methods of testing for the presence of salmon are being developed. Seattle officials hope that salmon populations will increase in Thornton Creek, where beavers have established a new dam on the project site.
Along with new research into stream ecology come better methods of stream restoration and the chance that salmon and other species will find a suitable home. The same can be said for such “adaptive management” in relation to shoreline, wetland and estuary projects that bring us closer to a true recovery of our native species.

Recovery of Puget Sound species could hinge on better understanding of ecosystems

A recent report from the Puget Sound Partnership helps us understand the difficulty of restoring the Puget Sound ecosystem. What caught my attention in the State of the Sound report was that after 20 years of protecting and restoring streams, wetlands, shorelines and estuaries, we have not increased overall fish and wildlife populations, and some remain in a downward spiral. (Our Water Ways, Nov. 3).
Several reasons have been given for the disappointing findings, including ongoing habitat losses from an increasing human population in the Puget Sound region. Clearly, there is a need to find ways to accommodate growth while protecting the remaining functional habitats.

Click on image to bring up Vital Signs wheel with links to extensive information about indicators, including key messages, strategies, background documents and other resources.
Info: Puget Sound Partnership

At the same time, I would like to focus some attention on the restoration side of the equation. It seems we may not yet understand what it takes to restore habitats in ways that allow the food web to thrive, thus allowing increasing numbers of higher predators, such as birds, salmon and killer whales.
I recently wrote about some bug-seeding experiments underway in several streams that flow through urban areas in Seattle (Encyclopedia of Puget Sound, Oct. 21). For some reason, populations of aquatic insects known to provide food for salmon were not recovered to the degree expected, given efforts to restore the stream channel, remove invasive weeds, plant native vegetation and reduce pollution to improve water quality. As a result, researchers launched a project of transplanting important insects from a healthy stream. So far, results are mixed.
Katherine Lynch, urban creeks biologist for Seattle Public Utilities, points out that restoration projects are often limited in scope and extent.
“The reality,” she told me, “is that when you go in and do restoration work, you are only doing a short reach. These projects (in Seattle) are a way of exploring what works and what doesn’t.”
To restore or improve salmon habitat in a stream, the challenge is to understand what has been broken in a complex interactive system. Factors include water quality, water flow, clean gravel, and the intricate interactions of the food web — from microscopic organisms to large fish, including predators that eat young salmon.
Emily Schwabe, left, and other members of King County’s bug-seeding team transplant rocks with attached invertebrates to Seattle’s Taylor Creek this past August. // Photo: King County

Take water quality, for example. Until recently, nobody knew what was killing adult coho salmon that found their way into urban streams. Scientists tracked the problem to stormwater entering the waterways from roads and highways. Then last year, thanks to advanced analytical tools, researchers were able to identify the killer compound, which comes from a chemical found in tires. Until then, nobody seemed to know anything about this chemical, let alone thinking that tires might have lethal properties. (EoPS, Dec. 3, 2020).
The discovery opened a lot of eyes to questions about how to identify “clean” water and the prospect that unknown chemicals may be causing unidentified problems in waterways throughout Puget Sound and across the country. The tire-related compound has been found to have lesser effects on steelhead and Chinook but no apparent effects on chum or sockeye. Work continues on varieties of species that might be exposed to road runoff, not just in urban areas but practically everywhere.
The discovery that dying coho could be linked to a tire chemical, known as 6PPD, and its deadly oxidation product, 6PPD-quinone, raises even more questions about the sublethal effects of other chemicals not yet identified. Standard water-quality tests cannot capture the toxicity of unknown chemicals in a stream. Even biological tests, such as using aquatic invertebrates (EoPS), may not reveal the toxic effects on vertebrates — such as fish, birds and humans.
Besides water quality, water flow may be a critical ingredient in stream restoration. I’ve been hearing a lot lately about hyporheic flow — the flow through gravel beneath a stream bed — and its effects on temperature (EoPS, Aug. 19) and oxygen supply, even its ability to filter contaminants.
In Seattle’s Thornton Creek, an understanding of hyporheic flow led to an engineered design in which the stream channel was dug out — up to 8 feet in some places — and replaced with gravel, according to Paul Bakke, owner of a firm called The Science of Rivers who monitored the physical functioning of the project. Rocks and logs were lodged in the streambed along with an impermeable barrier that forced the flowing water deep into the underlying gravel. The water plunges down into deep gravel, coming back up and diving down again several times in each of two reconstructed portions of the stream. The gravel helps filter fine sediments from the stream, but the configuration of the channel allows these fines to be washed on downstream during high flows, Paul explained. Organic chemicals in the water adhere to deeper gravel, where large fractions of chemicals are broken down by microbes.
A restored section of Seattle’s Thornton Creek soon after construction in 2014.
Photo: Seattle Public Utilities

A team of researchers affiliated with the Center for Urban Waters in Tacoma evaluated the fate of 83 chemicals moving downstream in Thornton Creek. Included were the toxic tire chemicals. The hyporheic flow path substantially improved water quality, according to the findings published in 2019 in the journal Water Research.
After construction of the hyporheic zone, Paul found that the vertical flow rate in the new gravel was 89 times higher than in the previous streambed, which had been impounded by a heavy sediment load. In fact, the fresh gravel produced a flow rate 17 times higher than in a forested stream in the mountains of Idaho.
The newly engineered stream also included a floodplain, created by removing flood-prone houses from the area. During high flows, sediment-containing water moves from the stream channel into the floodplain, where lower water velocities allow the sediment to settle out. That helps to protect the stream channel from excess sediment.
According to Paul, the key to success was rebuilding the stream by carefully choosing the width and depth of the channel and floodplain. The new configuration balances the forces of erosion and deposition, thus maintaining the channel in a more natural condition. In addition to Paul, the lead channel designer was Mike “Rocky” Hrachovec, owner of Natural Systems Design. For details of the design, check out the article in Research Outreach or the more technical article in the journal Water.
In October 2018, a pair of Chinook salmon spawn in a restored section of Thornton Creek. // Photo from GoPro video: Chapin Pier, Seattle Public Utilities

The ability of the restored sections of Thornton Creek to clean themselves, increase oxygen levels and mediate temperatures has led to a healthier condition, despite the urban setting in North Seattle.
In 2018, four years after construction, a female Chinook salmon swam warily upstream. With a male Chinook standing by, she deposited her eggs, which were quickly fertilized by the male.
“They spawned,” Katherine said. “We had never seen salmon spawn in the project region.”
A lack of funding and the COVID-19 pandemic have prevented further in-person monitoring of salmon movements, but new methods of testing for the presence of salmon are being developed. Seattle officials hope that salmon populations will increase in Thornton Creek, where beavers have established a new dam on the project site.
Along with new research into stream ecology come better methods of stream restoration and the chance that salmon and other species will find a suitable home. The same can be said for such “adaptive management” in relation to shoreline, wetland and estuary projects that bring us closer to a true recovery of our native species.