Fig Tree Logo

People build 'beaver' dams to clean stream

Kat Hall organized teams of volunteers to build Beaver Analog Dams.

By Mary Stamp

To help restore a wetland area along Thompson Creek as it flows into Newman Lake, Kat Hall, director of The Lands Council's Restoration Program, organized teams last fall to do what beavers do: build dams.

Working with Gonzaga's School of Engineering and Applied Science and its "Best Dam Team," they built "beaver dam analogs" (BDAs) by weaving tree branches through wooden posts pounded in across the creek at intervals over a length of 3,000 feet.

People are building "beaver" dams in other Northeast Washington locations where such dams are needed and beaver populations have declined as farmers and ranchers drained wetlands, said Kat.

She organized teams of staff and volunteers in October for the Beaver Dam Analogue (BDA) Thompson Creek Project to help keep sediment down in the creek to improve the water quality of the creek and lake.

Thompson Creek BDA Restoration Project paper shows posts driven into the creek and pine branches that will be woven around them.


Beaver dams do three things for the environment:

• They create pools or ponds that slow the flow of water to be absorbed to recharge the aquifer that is depleted as more people use the water.

• They assure that the dams filter sediment in the water so the water quality improves.

• They make the water pond behind the dams to create wetlands that are of value for wildlife.

"If there are beavers in the area to build dams, great, but areas that are drained and channelized lack habitat for beavers," Kat said.

"Healthy rivers wind and meander. Native vegetation along them slows and absorbs flooding," she explained.

"Many of the region's streams and wetlands were ditched and channeled to direct irrigation water for agriculture—crops and cows. As streams were ditched, spring runoffs eroded sediment off the land, degraded the water quality and lowered the water table," she said. "Those factors make it hard for native species to survive, reducing food for beavers.

 "Without habitat for beaver, human beings have come in to make beaver dams to do what beaver dams are supposed to do," Kat said.

"Building BDAs in a creek helps the sediment settle, fills up the deep channels and gradually raises the stream to the flood plain level, drawing the water table up with it," Kat said.

In addition, the upper watershed of Thompson Creek has old logging roads which channel a flow of phosphorous-laden sediment into Newman Lake. From the accumulation of those nutrients in the lake, there are blooms of algae, some of which are toxic to dogs and humans.

Kat started early in 2021, filing for permits in January and February, so The Lands Council could build 18 dams in October and November on Thompson Creek.

The council partnered with the Partners for the Fish and Wildlife Program at Turnbull Wildlife Refuge and Gonzaga.

Turnbull staff and a Gonzaga engineering class designed the BDA complexes. Mica Peak High School and EWU students helped build the dams.

To build them, volunteers used a post driver powered by a diesel air compressor to pound 8-to-10-foot posts in a line across the stream bed. Then the volunteers wove one-inch, 12-foot ponderosa pine seedlings or small branches from the bottom to the top of the posts. Small dams have eight posts and large dams have up to 70 posts.

Pine seedlings were cut from private land near Medical Lake and in Riverside State Park as part of a Department of Natural Resources (DNR) effort to thin forests for fuel reduction to prevent wildfires and improve forest health, Kat said.

"I love the synergy of working with private landowners, the DNR and state parks on forest thinning," she said.

The BDAs last one to five years or more. The posts and branches biodegrade gradually.

"I hope to see a difference in spring floods and lower phosphorous levels in the lake," Kat said.

"I've always wanted to improve the environment and help people live better lives," Kat said, noting that the balance of critters, wildlife, trees and shrubs needs to be restored. "Being outside in the natural world connects people with spiritual values."

The Lands Council also works with tribes. It partners with the Coeur d'Alene Tribe's restoration along Hangman Creek. It has planted trees and installed BDAs. It is also partnering on a biochar program with the Kalispel Tribe.

"When we do restoration, we do cultural resource reviews, letting tribes know what we are doing and where we are doing it and giving them the opportunity to participate," she said.

Growing up outside New York City, Kat did not want to live there with traffic and shopping malls, even though it was 10 minutes to the ocean. She had her eyes set on moving west.

After graduating in 1994 from Cornell University in Ithaca, she did a two-year agroforestry project in Cameroon with the Peace Corps, volunteered another year and then backpacked with a friend in Southern and East Africa.

Back in the U.S., she took a job with the Serve Alaska Youth Corps in Juneau, maintaining hiking trails and doing environmental education. Then she did short-term jobs in Alaska, working on a fishing boat one summer, doing trail maintenance, working at a fish hatchery and organizing outdoor therapy for disturbed youth.

From 2001 to 2003, she completed a master's degree in environmental management at Yale University and returned to work three years with the Southeast Alaska Conservation Council.

She came to Spokane to contract with The Lands Council and was hired in 2007 as staff for the environmental health program. That evolved into outdoor environmental education with middle and high school youth.

"We took them to do environmental restoration as science projects in classic outdoor-education programs, including planting trees, testing water quality and hiking," said Kat.

"When people are outside, planting trees, they learn about trees and how trees help rivers," she said. "The goal is for kids to connect or reconnect with nature by getting their hands dirty and feet wet. When they are off their devices, we instill values as we converse outside with the youth.

"Kids learn science while snowshoeing up Mt. Spokane. Many complain while hiking up, but at the top, they are in awe. On the bus back, many say it was the best experience of their lives," Kat said. "I've been doing that for 14 years and plan to continue."

She works with Maia Inniss on outdoor youth education and a Northeast Spokane project to plant 200 street trees to absorb storm water and build community.

The Lands Council recently hired Naghmana Sherazi as climate justice program director to deal with local and regional climate issues. Its new public lands program director, Adam Gebauer, is leading a forestry coalition and wildlife programs for beaver and caribou.

The Lands Council's executive director, Amanda Parrish, added that the council is planning its 27th Annual April Showers Auction for Saturday, April 16, to raise funds to support restoration and revitalization of Inland Northwest forests, water and wildlife.

Kat said The Lands Council is also working on riparian restoration to plant trees and shrubs along streams 1) to improve water quality by preventing soil erosion as roots keep the soil in place; 2) as a buffer to break down and filter contaminated runoff of pesticides from farms and roads, and 3) to shade and cool the water temperature so the water holds dissolved oxygen for fish and macroinvertebrates—like aquatic insects—and supports natural vegetation for wildlife habitat.

For information, call 209-2403 or email

Copyright@ The Fig Tree, March, 2022