Restoring Cold Water in the Willamette River








Willamette River Water Temperature

Helping water utilities invest where it matters most for fish.



The Willamette Valley is home to two-thirds of Oregon’s population and over thirty species of native fish, including endangered Chinook salmon and steelhead trout. Every natural and human community in the valley relies on the Willamette River to provide plentiful, clean, and cool water. Federal and state requirements protect fish that need cold water as they travel upstream from the ocean to spawn. That can mean costly investments for the facilities that process warm water from homes and businesses before releasing it back into the river. We’re helping utilities, regulators, and conservation groups make sure those investments in improving water temperature in the Willamette River can go where fish need them most. And, in this case, what’s best for fish also costs less for utilities and ratepayers.



Like many big rivers, the Willamette is heating up, and that’s bad for salmon and cutthroat trout, the Northwest’s most iconic fish species.


The good news is that we know what we need to do. Big, slow, rivers like the main stem of the Willamette have always been warmer than these migratory fish prefer, but that’s okay if they can find pockets of cold water to take breaks. These riverine rest stops are known as “cold water refugia,” and they are associated with the natural processes of a natural and dynamic river system. And the restoration community has a lot of practice restoring natural processes of rivers like cold water refugia, thanks in part to great support from the Willamette River Initiative these last 9 years.

If water utilities could invest in restoration to meet their permit obligations around water temperature, they could save money and millions of dollars could flow to restoring cold water for native fish in a resilient Willamette River.


The wastewater treatment and industrial facilities that process our warm water have Clean Water Act permits that restrict what they can send back to the river. One such requirement could be restrictions on how warm the water released can be, which is measured by “thermal loads” or the units of heat energy that change water temperature. Under current policies, the conventional option for most wastewater utilities to meet their thermal load limit is often to install a multimillion-dollar chiller (think: giant cooling tower), despite massive costs to ratepayers and minimal benefit to fish.

So, why can’t we invest in restoration projects that cost less and do a better job a cooling the river to meet these regulations instead? The short answer is there are lawsuits still getting settled, questions around the best path forward legally and scientifically, and a lot of partners that need to agree.

There is an opportunity to build on the momentum of the Willamette River Initiative as it wraps up and to fund the next decade of restoration in Western Oregon’s biggest river. The Association of Clean Water Agencies, Willamette Partnership, and other partners are working to make the right choice the easy choice so that utilities across the valley can save ratepayer dollars on Clean Water Act compliance and contribute to the restoration of cold water for native fish. Willamette Partnership’s job is to build momentum and consensus around a path forward to make restoration for regulatory compliance possible.

Get in touch about restoring cold water in the Willamette River.


Kristiana Teige Witherill staff photo


Have questions about our work with Willamette River temperature?

Kristiana Teige Witherill, Partner, Natural Infrastructure
email |
office | 503.946.1904

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