Low water levels in the Chehalis River have often been discussed through the use of photos and sensors that measure water flow.
But seeing the river and crossing it on foot, knowing that it will be flowing high and fast in just a couple months, brings the issue into focus.
Twin Harbors Waterkeeper Lee First led a three-hour river walk last week with a small group of local, state and tribal officials to see the river and discuss the impacts of the recent drought on the basin and the wildlife it sustains.
The group set out from a piece of private property in the Rochester area around 1 p.m. on Thursday, Sept. 4, followed by two journalists from The Chronicle.
While First led the group, she was joined by Lea Ronne, a salmon and steelhead biologist with the Washington state Department of Fish and Wildlife, as well as Farley Youckton, a water coordinator for the Confederated Tribes of the Chehalis Reservation. The tribe’s Chehalis Basin noxious weeds coordinator Sofia Sherman also joined the group.
After the group set out, it took about 30 minutes to walk a winding trail from the private property to the main stem of the Chehalis River. Much of the land the group crossed will be flooded or part of the river in just a few months. Upon reaching the river, the reality of the words “low flow” became clear.
The group immediately pointed out how different the river looks from its normal levels.
Small rocks and patches of mud that should make up the river bed are easily visible, including a bit of land that is currently an island, but in six months will be entirely submerged. Much of it is covered with algae or other plants that would prefer to be under water. In fact, the water was so low, the group was able to cross the river on foot without getting their knees wet.
Despite a few recent periods of rainfall, Ronne and First insisted that the basin is not out of the woods yet and still faces challenges due to the abnormally low flows this summer.
“It’s better than nothing,” Ronne said. “I think one of the tricky parts is how quickly you get to an atmospheric river, but it's not staying. It's not replenishing the groundwater because it's running off so quickly.”
Since most of the Chehalis River Basin is rain fed and not supported by glaciers or major snow packs, the basin is particularly vulnerable to drought. Rain feeds the river directly, but it also runs into the river through groundwater. During the dry season, rain struggles to keep up and replenish the aquifer that keeps the river healthy and cool while supporting local communities and farmers.
The discussion centered around impacts to aquatic life, mainly salmon and steelhead, but also the impacts to other important parts of the ecosystem, including freshwater mussels and native plant life. According to both Ronne and First, the basin faces two main challenges during a drought: low water and warm water.
According to Ronne, in previous years, extreme low flows have completely changed where salmon spawn.
“That’s one shift to the basin of having the low flows is they can’t get to ideal spawning habitat,” Ronne said. “Depending on the time of year, there could be eggs in the river, and those warmer flows and lower flows can reduce the survivability of those eggs.”
The low flow also impacts where in the river the fish might lay their eggs, often looking for deeper and cooler parts in the middle of the stream that, come winter, could be smothered or scattered by the extremely fast moving waters of the Chehalis River. These types of effects can lead to long-term impacts on salmon and steelhead.
The low flows also mean salmon have a harder time getting upstream and, when they do, the shallow pools are so warm they cause stress, lower oxygen levels and higher rates of infection, leading to high mortality rates of the vulnerable species.
“Low flows create a cascade of problems for salmon and steelhead,” Ronne said. “Shallow rivers warm quickly. Once temperatures rise above 16C, fish become stressed and above 20C, conditions can be lethal. When you add in human-made barriers like temporary rock dams, these conditions compound, blocking migration and concentration of fish in warm, stagnant water where mortality risk is highest.”
First measured water temperatures during the river walk, finding temperatures between 22 and 24 degrees celsius.
During the walk, the professionals also discussed other impacts to the river itself, with algae mussels and other wildlife being left on dry land to dry out in the sun. Algae blooms and other plant dieoffs, according to Ronne, can lead to less oxygen in the river affecting not just fish but all of the species inside.
While the group expressed mostly concern during the tour, Sherman offered a small silver lining relevant to her work in managing noxious weeds in the basin. She said the dry weather can be an opportunity to remove invasive plant species such as Japanese knotweed while it's vulnerable. The slow flow also means the river can't spread the plant's seedlings as easily.
