Tacoma — Biologist Kristin Evered spent much of this summer battling beavers in the Puyallup River watershed. The woman versus rodent scrimmage was over a dam that was drastically changing acres of wetlands.
Final tally: Beavers 30, biologist 0.
“You have to give them credit,” Evered said during a tour of the site along Pioneer Way East this week. “They definitely are hard workers and industrious. They don’t sit around much.”
Evered works for the Port of Tacoma and spends part of her time monitoring the port’s wetlands mitigation properties. That includes 40 acres of upper Clear Creek, a tributary of the Puyallup River. The former agricultural land was rehabilitated into wetlands in 2016 for $9 million. More than 140,000 plants were put in the ground.
In late 2022, it became apparent that a family of beavers had moved into the property and dammed the creek. Soon, water was backing up into ditches and agricultural fields and killing native trees by flooding their roots.
Now, both the beavers and the Port are happy thanks to the work of “beaver deceivers” who pulled a fast one on the buck-toothed rodents without harm.
Notching
The easiest way to get rid of a beaver dam is to dismantle it. They’re not Grand Coulee — just mud and sticks. Earlier this year, Evered created a notch in the dam by tearing out a section of branches and dirt. That allowed water to flow and the pond level dropped.
But what beavers lack in technology they make up for in tenacity. They began repairs as soon as Evered left.
So, Evered returned and notched the dam again. And again. Some 30 times she tried to dismantle Beaver Bonneville and every time, the beavers quickly repaired it.
“The beavers were rebuilding the dams faster than we can notch them,” Evered said. “There’s a reason they’re called busy beavers.”
Beaver home
The North American beaver (Castor canadensis) can be a contentious issue across the west. There are debates on their native range and whether they are a help or a hindrance to the natural environment. The issue can be polarizing.
Beavers use their formidable teeth to cut through small trees they then carry or float downstream to build their lodges and dams. They prefer willow.
At the Clear Creek site, the beavers’ lodge is located within supervising distance of their dam. Beaver dams are crucial to maintaining the safety of their lodges, which typically have two underwater entrances, hidden from predators. Inside, there are “bedrooms” and “living rooms”.
Beavers aren’t villains
Killing the beavers wasn’t an option although it did come up in the discussions with various agencies, Evered said.
“I never entertained it because I think beavers provide so many ecological benefits that you can’t replicate,” she said. “But I also want to be a good neighbor.”
Beavers can be a benefit to an ecosystem. Their dams slow water return to salt bodies like Puget Sound and recharge aquifers with fresh water. They trap sediment and filter water.
But wetlands maintain a delicate balance of grass, brush and tree species with differing tolerances for water saturation. Some like their roots wet continuously while others prefer only the occasional dip.
At Clear Creek earlier this year, young spruce and mature cottonwoods were in danger of succumbing. While both species can handle semi-wet conditions they can’t survive in a continuously flooded environment.
The wetlands beavers create can nourish scores of animals and plants. On a recent day, a blue heron took flight from near the dam. The birds have a rookery nearby. Evered has seen bald eagles, muskrats, American bitterns, fish and amphibians using the site.
On this late summer day, Chinook salmon were swimming upstream on a nearby channel unaffected by the beaver dam. Water in both channels was nearly clear.
Dam sham
In July, after about 30 notching efforts, Evered realized she had met her Waterloo.
That’s when she joined forces with Beavers Northwest, a nonprofit organization that serves as a mediator of sorts between beavers and people. The group offers technical advice, education and habitat restoration all designed to keep both beavers and their human neighbors happy.
Evered didn’t need a drastic drop in the pond’s water level — just enough to keep ditches and trees from flooding.
The answer was to place a culvert into the face of the dam. Beavers Northwest calls them pond levelers. The culvert’s inflow extends into the pond and has a cage built around it. The outflow extends far into the creek so that beavers can’t hear water rushing out of it. That sound, Evered said, is what triggers the beavers’ instinct to repair their dam.
“It’s like deceiving them that the dam is still whole while the flooding is released,” she said.
After the pond leveler was installed the water level dropped only nine inches. But that was enough to keep upstream land draining while not alarming the beavers.
“There has been a marked difference for the neighboring properties,” Evered said.
Previously, Evered hadn’t had much experience with beavers. She now has a new respect for them, particularly their dam building techniques. Beavers, it turns out, are better recyclers than people. Evered found a shirt, whiskey bottles, a bucket, and a birdhouse that beavers had used in their dam construction.
“I feel optimistic,” Evered said, dressed in chest waders, preparing to head back to the dam this week. “We developed a solution that makes everybody happy.”
