It Takes a Community: Lemhi Basin Stream Restoration
Article by Lucy Littlejohn (Fish Biologist, BLM Salmon Field Office), Ethan Ellsworth (Wildlife Biologist, BLM Idaho State Office), Dave Hu (Fish Biologist, BLM Washington Office), and Hannah Nikonow (Intermountain West Joint Venture)
Snowmelt from the looming Beaverhead and Lemhi Mountains flows into wooded mountain valleys and across open sagebrush flats tilting toward Idaho’s Lemhi River. This small river, in turn, meets the Salmon River of No Return, which winds and plummets across the central part of the state before joining the Snake River, the Columbia River, and, eventually, the Pacific Ocean. Though these landscapes have changed with the mechanization and growing populations of the 21st century, the rivers and fish flow through sagebrush country and provide the lifeblood for the recreation and agriculture industries that fuel regional economies. Maintaining this system’s connectivity is a priority for the Bureau of Land Management, Idaho Fish and Game, The Nature Conservancy, Idaho Governor’s Office of Species Conservation, Intermountain West Joint Venture, and many other partners. The following story details how there are so many working together to achieve this.
A Rich Past and a Changing Landscape
Historically, the Lemhi River and its tributaries were important habitat for the Snake River’s fall-run Chinook salmon, Snake River Basin’s steelhead, and Columbia River’s bull trout, as well as rainbow, redband, and westslope cutthroat trout. The salmon and steelhead travel 800 miles from the ocean to the Lemhi River to spawn, making this the longest anadromous fish migration in the Lower 48 states.
For millennia, the Lemhi Shoshone Tribe, or Agai’dika (“salmon eaters”), counted on large runs of salmon and steelhead returning from the ocean. These fish played a key subsistence role for the people and figured prominently in their traditional and ceremonial life. The fish were once harvested in great quantities, but these runs have diminished significantly since European settlement.
Over the past 150 years, a network of irrigation diversions and ditches were built in the Lemhi River Sub-basin to develop the local agricultural economy and support growing communities. Some early irrigation practices were found to dewater streams and strand fish in the irrigation ditches and fields. Juniper and sagebrush grew in the dry streambeds, replacing willow, water birch, and cottonwood trees.
The Story of Hawley Creek
Hawley Creek is key tributary habitat for Endangered Species Act-listed fishes and an example of important landscape connectivity with healthy sagebrush uplands, riparian corridors, wet meadows, and the irrigated agricultural lowlands. The lower 6.5 miles of Hawley Creek ran dry for over 100 years due to some past irrigation practices that disconnected this tributary from the river and its many users – including fish, beavers, and humans.
In the fall of 2016, work began to restore Hawley Creek. Local agency, non-governmental organization (NGO), and landowner partnerships aimed to re-establish year-round flow and connection to the Lemhi River by replacing check dams and culverts with fish-friendly diversions and bridges, installing fish screens, and improving irrigation efficiencies.
The Hawley Creek project objectives included reconnecting Hawley Creek Watershed and the Lemhi River to re-establish fish passage, restore channel processes, improve groundwater storage and floodplain connectivity, and provide efficient, fish-friendly irrigation systems. The following actions have been completed to meet these objectives:
- Replacing three unscreened fish barrier diversion dams with two fish-passable screened diversions with lockable headgates.
- Replacing open ditches with miles of metered pipelines to conserve water and eliminate overland flooding of BLM sagebrush habitat.
- Bringing water rights and points-of-use into legal compliance.
- Installation of on-farm pivot systems and nozzles to control water where soil conditions dictate measured application and rates.
- Replacing four fish passage barrier culverts with channel spanning bridges.
- Reducing livestock pressure on the stream by installing two pressurized pipelines with four off-channel, upland water troughs.
- Closing four unauthorized vehicle fords and armoring two other vehicle fords.
- On-going riparian planting.
- Building 30 beaver dam analog structures on the upper reach of the project area. Additional BDAs will be built between 2020 and 2030.
To date, around $4 million has been invested to improve Hawley Creek and restore its functionality for the entire community of users.
“Beavers” Work on the Creek
Beavers were also an important part of this system, as they beneficially influenced aquatic, riparian, and wetland habitats. Channel dewatering as a result of human activity reduced woody riparian plants beavers used for food and dam construction. This caused a cascading ripple of negative ecological impacts for all species that are dependent on year-round water in the arid West.
Beaver Dam Analogues (BDAs) are a pivotal tool to put Hawley Creek back together. This low-tech tool can jump start ecosystem restoration in low gradient stream reaches. Installation is done by hand: untreated, sharpened fence posts are driven into the stream channel. Willow branch cuttings are woven between the posts to create a semi-permanent, porous dam that naturally accumulates woody materials and mimics natural beaver dams.
Installation of Hawley Creek BDAs began in September 2017 and is on-going. Monitoring shows the BDAs have improved riparian, wetland, mesic, and aquatic habitats for ESA-listed fishes, and BLM sensitive westslope cutthroat trout and sage grouse. Sage grouse hens with broods are frequently seen in the new mesic-riparian habitats. Kingfishers, great blue herons, common nighthawks, and a variety of ducks are utilizing the habitat created by the BDAs. These riparian and open water habitats also support the highest levels of bat activity and species richness.
All Hands-In Make a Vibrant Future
Bringing lots of pieces together, the partnership of interagency, NGO, and landowner restoration actions has eliminated fish mortality; improved aquatic, riparian, wetland, and mesic habitats; restored perennial flow; reconnected Hawley Creek with the Lemhi River; and enhanced the irrigators’ water delivery systems.
Beavers are expected to return and complete the work the partners initiated when the riparian vegetation can support them. It is also hoped Chinook salmon and steelhead will spawn here again someday.
Seeing this stream return so vibrantly required a colossal partnership effort. It is amazing what can be done by such a diverse collaboration of local citizens, landowners, state and federal agencies, and NGOs rallying around a collective vision to restore and protect the natural resources that connect us all. The future is bright for America’s working lands and the animals and resources that depend upon them in the Lemhi River Valley.