Climate change

Climate change and the Chehalis River: Experts outline potential dangers to fish and flooding

By Isabel Vander Stoep / [email protected]

Editor’s note: This story is part of “Headwaters to Harbor”, a project by The Chronicle to document the Chehalis River from Pe Ell to Grays Harbor while highlighting the people and issues of the river along the way. Our coverage is compiled at

For the Chehalis River Basin, the models show that over time, climate change is very likely to alter the landscape as communities know it today.

In reports sent to The Chronicle by the Grays Harbor Conservation District and the Chehalis Basin Office, models show warmer temperatures, longer dry seasons and more flooding.

Mara Zimmerman, executive director of the Coast Salmon Partnership and Foundation, summarized effects on the Chehalis Basin into the same three categories.

These combined impacts would amplify perhaps the most significant problem in the Chehalis Basin: there is too much water for part of the year, and not enough for the rest.

With warmer waters, salmon would have fewer places to spawn and survive. During longer and hotter dry seasons, junior water rights holders would see their rights reduced more regularly, leading to shorter irrigation seasons and other economic impacts. With more rain in winter, catastrophic floods are expected to become more frequent and more damaging.

Overall, climate change is a threat to the assets of the Chehalis tribe, farmers, fishermen, flood victims, loggers and environmentalists.

“Things are changing rapidly in the rivers and in the ocean. And there’s really nothing we’re doing here that can control the ocean. But I think it’s important to have that in mind because for salmon, the ocean and the river affect their survival,” Zimmerman said. “For the people (in the Chehalis River Basin), the rivers are really the key because it’s the rivers that interact with their lives.”

Fish and flood

When Governor Christine Gregoire appointed members to the Chehalis Basin Task Force in the 2010s (which later morphed into the Chehalis Basin Council), it was recommended that the group work to reduce the damage caused by flooding and restore habitat for aquatic species in the short term while considering long-term strategies to address flood damage and improve aquatic habitat.

In simplified terms, conversations between major entities along the Chehalis River tend to fall into two categories: fish and flood.

If no mitigation takes place, climate change models show that fish populations decline and flooding worsens.

The largest floods recorded on the Chehalis River have occurred in the last 35 years alone, in 1990, 1996, 2007, 2009 and 2022.

“Using these revised projections of future climate conditions, a catastrophic flood is now estimated to occur at a recurrence interval of 10 to 50 years,” said a Chehalis Basin Strategy memo.

Although explaining climate patterns is not his area of ​​expertise, Zimmerman cited the Newaukum as a clear example of change over the past few decades.

“Peak flows have increased (on the Newaukum River) over time over the past 50 years. And it’s a very clear model. It is change. And I want to point to the data sets that we have that show that change is already happening to say, “Listen, whether or not you think this predicted trajectory is going to happen in the future or not, that change has happened” , Zimmerman said. . “And we have to think about what that means and how we can do things.”

In “Chehalis: A Watershed Moment,” a documentary about the basin and its struggle with flooding and declining fish populations, former Lewis County Commissioner Edna Fund said, referring to the flooding of 2007: “When we think about global warming and other issues that are ahead of us, we have to do something. We simply cannot let this happen again.

The Chehalis River basin is also the last in the state to have no species of salmon listed as endangered under federal law, but fish populations are still severely depleted, especially spring runs. of Chinook. According to the memo, spring populations of chinook in the basin are currently about 23% of the size of historical runs.

Zimmerman said higher temperatures and longer dry seasons reduce habitat. And less habitat means less fish.

Grays Harbor Conservation District superintendent Anthony Waldrop said rising sea levels will also negatively impact river ecosystems, not just salmon.

“The multi-decade prediction is that high tides will get higher and higher upstream,” Waldrop said. “In the long term, this could radically change the landscape.”

In a 2015 Wild Fish Conservancy Northwest report sent to The Chronicle by Waldrop, sea level rise predictions showed significant saltwater intrusion upstream that could kill most salt-intolerant tree species. in the forest, destabilizing the banks by the action of the floods. and tidal waves.

More salt water further upstream would also harm coho salmon, which take refuge there in winter, the report said.

“Work for everyone”

These models are based, as we said above, on a world without mitigation measures and without projects to ameliorate habitat decline and flood damage. The real Chehalis River Basin has people who dedicate their entire careers to tackling these issues from miles above Pe Ell to the Pacific Ocean.

This is where Zimmerman rests his head.

“I have great faith in people to solve problems. I really think we have a lot of really dedicated minds and people thinking about basin issues now,” she said. “These solutions are found when people come together with different understandings and points of view. And I think that’s also happening in the Chehalis Basin. Flood issues are complex. They are not resolved by a single point of view. They are solved by people who understand how it affects the whole community.

Planting trees allows for more stable banks, more sharing and therefore cooler water. The Chehalis Basin Land Trust and the Lewis County and Grays Harbor Conservation Districts all work with the public to plant trees along the river throughout the year.

Large log jams in the river cause scouring of the river bed giving salmon more places to spawn and lay eggs. Current river bank stabilization projects, such as Newaukum Valley Road, use innovative techniques to both prevent bank erosion while capturing more timber to create traffic jams. Creative projects like this – for which the Lewis County Department of Public Works won the Project of the Year award – can simultaneously protect human interests and salmon.

Farmers have adapted to flooding with mats of creatures, giving livestock high ground during winter storms. People built houses and regulations on building in the floodplain became stricter.

“These are solutions, I think, that we find that somehow work for everyone. And that’s a big deal,” Zimmerman said.

With so many people in the Pacific Northwest whose livelihoods are tied to natural resources, such as loggers, fishers and farmers, she said convincing them the problem exists or that people should be good stewards of the Earth is not the biggest problem. Likewise, the Chehalis tribe need not be convinced that climate change is affecting salmon populations so closely tied to their culture, because they have seen it firsthand, she said.

The hardest thing to address, Zimmerman said, is how many people, both in Chehalis River-related projects and members of the general public, react to the subject of climate change by imagining clouds of unhappiness above.

Instead, she tries to see the opportunities.

“If we start the conversation talking about what we have to give up, you’ve kind of lost the conversation, haven’t you? But, if you start a conversation thinking about what we have to gain.

“…This is where we start to meet spirits,” Zimmerman said.