The Chehalis River Basin likes to be dramatic.
While many rivers flow west toward the Pacific, the Chehalis flows east first. It’s the largest river basin fully situated within the state of Washington — the Columbia River’s tributaries creep into parts of seven states and Canada. It’s one of the last salmon strongholds in the state without an endangered species listing.
It’s also fully rain-fed. And with climate change bringing longer, hotter, dryer summers to the region, experts in the basin are worried critically low flows and high temperatures in the river will be detrimental to aquatic species.
As The Seattle Times reported last fall, 2022 saw the fewest Chinook salmon egg nests in years along the Newaukum River. The mainstem Newaukum River is designated as “core summer salmonid habitat.”
The designation allows the state to limit human activities after streams reach a certain temperature. In the Newaukum, the cut-off is 16 degrees Celsius, equal to 60.8 degrees Fahrenheit. Migratory salmon aren’t suited for temperatures much higher.
“Unfortunately, it looks like we are well past the 16 C criterion,” said Kirsten Harma, watershed coordinator for the Chehalis Basin Partnership. “(The) South Fork and mainstem Newaukum are already in the low-mid 20s.”
Nearly 70 degree water sounds alright for swimming, but the high heat means less oxygen stored in the water for fish and other aquatic life. The heat also contributes to low flows.
“Less water means less habitat,” Harma said. “The fish and wildlife that depend on streams right now are under a lot of stress.”
It’s so low on the Newaukum right now that scientists can’t definitively measure the river against historic lows, she said, chuckling at the irony.
The United States Geological Survey, or USGS, keeps gauges along the river calibrated to “base flows,” Harma said. With such unseasonably low water levels, it’s hard to get good data.
Gregg Peterson, a Boistfort area resident, experienced this when posting about what appeared to be the lowest flows on the Chehalis near Grand Mound in 160 years. After contacting USGS, he learned the flows are unseasonably low, but not yet centurial.
Nonetheless, Harma and other scientists are certain the term “critical” covers their bases for the dire situation aquatic species find themselves in, according to a multi-agency news release sent to The Chronicle and Aberdeen’s The Daily World last week.
“Juvenile salmon are especially vulnerable to temperature and water level changes. Even small variances can exponentially increase their mortality rate,” said Megan Tuttle, a regional biologist for the Washington Department of Fish and Wildlife (WDFW), in the release. “Please report any dead or dying fish to WDFW and leave carcasses in the river.”
Mara Zimmerman, executive director for the Coast Salmon Partnership, said the low flows and high temperatures cause juvenile salmon and trout to “crowd together” in limited areas, forcing them to fight for resources, thereby impacting their growth and survival rate.
Low flows are as problematic for some farmers as they are for fish.
Access to water in the American West is mostly on a first-come, first-served basis.
Water rights — permission to collect water from a certain body in a certain quantity — were established in Washington in the early 1900s. The older a water right is, the better.
The Chehalis has a special designation known as “in-stream flow regulation," which essentially gives the river its own water right.
For those whose rights precede the in-stream flow rule, access to the river water isn’t limited. But, for the 93 junior water rights holders in the basin, their rights are cut off after levels reach a certain point. To read more about how water rights work locally, previous reporting in The Chronicle can be found at https://bit.ly/water-rights-chronline.
There are some actions recreationalists and water users could take to benefit the Chehalis River for the remainder of the dry season, Harma said, including:
• Not swimming in deep pools in the river where Chinook salmon may be trying to keep cool as swimming stirs and warms the water.
• Not blocking streams with “rock dams” which make it harder for fish to move upstream and find cooler areas.
• Limiting well water used for lawn and garden watering as most wells in the Chehalis Basin are connected to a stream or river.
Usually, up-to-date data on flows can be found at USGS.gov under “Science,” “Water” and searching by location. There, residents can also find water quality reports and other information on their local streams.
