Thumbnail Lemhi sampling infrastructure figure

Project Contact:  

Laurel Faurot, QCI Inc.
Richie Carmichael,  QCI Inc.


Lemhi (ID)

Key Management Question 3

The Lemhi River, a tributary of the upper Salmon River in Idaho, is managed as an Intensively Monitored Watershed (IMW). While 93% of the watershed is federally managed, the majority of the valley floor along the mainstem Lemhi is privately owned. At the inception of ISEMP, over 322 know irrigation diversions were operated to support agriculture, resulting in the dewatering of 28 of the 31 major tributaries to the mainstem Lemhi River. Moreover, the lower 48 kilometers of the mainstem Lemhi River have been simplified by road construction and agriculture. Local managers believed that loss of access to historically important tributary habitat and mainstem habitat simplification reduced the freshwater productivity of spring/summer Chinook salmon and steelhead in the basin.

The Lemhi Intensively Monitored Watershed monitoring strategy focuses on collecting fish and habitat data to inform a species-specific life cycle model.  The model can then be used to predict the effects of restoration scenarios on fish populations.

In Progress 

  • 2013: Project initiated

Findings and Uses

To date, tributary reconnection actions have almost doubled the length of stream available to anadromous salmonids, increased available stream area by 22%, and resulted a 19% increase in pool area.

Adult escapement, juvenile rearing, and increased densities of juveniles have been documented in restored habitat. Steelhead spawning has been documented in all reconnected tributaries; however, an increase in spring/summer Chinook or steelhead has not yet been detected, although it is predicted.

ISEMP’s development of quantitative fish-habitat relationships has improved our ability to identify life-stage-specific limiting factors and target habitat restoration actions to address them. Monitoring of site-based actions has increased our understanding of time-lags between project implementation and biological response. Most importantly, Lemhi IMW lessons are transferable to other watersheds in the interior Columbia River Basin, enabling more effective restoration elsewhere.

Tributary reconnections in the Lemhi River

Tributary reconnections in the Lemhi River

Modeled change in restoration anticipated from Lemhi River restoration actions completed through 2016

Modeled change in restoration anticipated from Lemhi River restoration actions completed through 2016

Restoration Actions

Conservation MeasureTitleGeographic AreaObjectiveDescription
CM-01Lemhi River Tributary ReconnectsLemhi River TributariesFish passageProvide hydraulic and ecological connectivity between the Lemhi
CM-02Removal of Irrigation Structures and Road Culverts that Inhibit Fish PassageBasinwideFish passageIdentify fish passage problems and improve fish passage throughout the Lemhi River basin
CM-03Fish Screening to Reduce Entrainment in Irrigation CanalsBasinwideFish passageScreen irrigation ditches to reduce entrainment and associated mortality of fish in tributaries
CM-04Eliminate Ditch Return ThreatsBasinwideFish passagePrevent fish from entering irrigation ditches from the downstream end
CM-05Riparian Grazing ManagementBasinwideRiparian habitat protectionImprove riparian zones along the Lemhi River and tributaries to rehabilitate fish habitat
CM-06Enhance Side Channels and Secondary Rearing ChannelsMiddle Reach
Upper Reach
Stream habitat improvementProvide fish access to side channels to enhance spawning habitats and juvenile rearing capacity
CM-07Lemhi River Stream Channel RehabilitationLower Reach
Middle Reach
Upper Reach
Stream habitat improvementRestore large segments of the Lemhi River to improve habitat condition for spawning and rearing
CM-08Pool DevelopmentLower Reach
Middle Reach
Upper Reach
Fish passage
Stream habitat improvement
Improve fish passage and rearing in the Lemhi River by increasing the number of pools
CM-09Maintain Biologically Sufficient Conditions for Fish Passage in the Lower Lemhi RiverLower ReachFish passageMinimum continuous stream flows below the L6 diversion and modifications to the river channel would be used to maintain biologically adequate fish passage for access to the middle and upper river reaches and tributaries
CM-10Upper Lemhi River Chinook Salmon AssessmentUpper ReachStream habitat improvementMcFarland stream flow and fish performance study
CM-11High Volume Flow to Improve Instream Habitat ConditionsUpper ReachStream habitat improvementProvide high volume stream flows to maintain stream channel complexity and rehabilitate fish habitat
CM-12Maintain Fish Passage in the Lower Reaches of Hayden CreekHayden CreekFish passagePreserve continuous flows that historically have been available in lower Hayden Creek for migrating fish


Lemhi Expert Panel Product Description

Lemhi Expert Panel Products Available Upon Request