Middle Lemhi River – Henry Reach

Salmonid Habitat Restoration and Acquisition

Instream Habitat Riparian Habitat
Project ID007 18 SA
Recovery DomainsInterior Columbia
Start Date12/01/2018
End Date12/31/2021
Year2018
StatusCompleted
Last Edited04/27/2022
 
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Description    


The Middle Lemhi River Henry Reach is a 0.65 mile segment of the Lemhi River located approximately 2 miles downstream of the confluence of Hayden Creek and the Lemhi River. The pre-treatment project condition included a confined river segment that was largely isolated from its historic floodplain. Bank armoring (e.g. rip rap) previously installed to stabilize stream banks adjacent to a pasture and irrigation diversion substantially limited lateral floodplain interactions. This reach was void of woody structure, offered minimal lateral habitat such as alcoves or secondary channels, and contained high water velocities that offered poor quality rearing habitat for summer parr and winter pre-smolt life stages.

The Middle Lemhi River Henry Reach expanded approximately 0.65 miles of the Lemhi River into more of a natural floodplain to encourage natural river processes and increased habitat capacity for juvenile life stages of ESA listed fish. Objectives included increasing river sinuosity, developing habitat complexity, encouraging floodplain engagement, development of secondary channels, and enhancing riparian zones. Project actions included excavation of multiple channels and pools, installation of instream wood structures, construction of a channel inlet and engineered riffle to provide water to a developed floodplain, channel banks were graded to increase lateral flooding potential, and logs and vegetation were used to stabilize the streambank. Once construction was completed, all disturbed areas were rehabilitated by planting willow stakes, seeding, and placing loose woody debris that was generated when the channels were excavated. Cattle exclusion fencing was installed to prevent livestock from entering the project.

This project received an amendment to increase funds and the project scope in November 2019. The database has been revised to reflect the increase in funds and the additional metrics. Note that this project was multi-year funded from FY16 and FY18.

Project Benefit    


Completion of the Henry Reach project is expected to improve freshwater productivity of Chinook salmon and steelhead in the Lemhi River. Substantial lateral fish habitat has been created that regularly floods during certain times of the year. Floodplain benches containing thick stands of riparian vegetation are now bisected with multiple channels, and the sinuosity of the Lemhi River has been increased. Furthermore, the project is located just downstream of two primary Chinook salmon production areas. IDFG has determined that some of the highest juvenile densities in the watershed occur in this area (IDFG unpublished data). Thus, the relative benefits of this project are expected to be high. Immediately upstream of the project site, the Lemhi River is a heavily incised single thread channel with no functional summer rearing or wintering habitat. As such, the project will function as a “catcher’s mitt”, providing much needed habitat for large numbers of rearing parr that were displaced in the spring from upstream production areas, and for abundant pre-smolts moving out of the production areas in the fall in preparation for overwintering.

Accomplishments

Metric Completed Originally
Proposed
Instream Habitat
  Stream Miles Treated 1.00 1.00
Riparian Habitat
  Stream Miles Treated 1.25 1.25
  Acres Treated 1.2 1.2

Funding Details

SourceFunds
PCSRF$475,233
Other$309,329
Report Total:$784,562


Project Map



Worksites

Lemhi Henry Reach    


  • Worksite Identifier: Lemhi Henry Reach
  • Start Date: 12/01/2018
  • End Date: 12/31/2021
Area Description
Lemhi RIver

Location Information

  • Basin: Salmon
  • Subbasin:
  • Watershed:
  • Subwatershed:
  • State: Idaho
  • Recovery Domain: Interior Columbia
  • Latitude: 44.898049
  • Longitude: -113.625949

ESU

  • Snake River Basin Steelhead DPS
  • Snake River Spring/Summer-run Chinook Salmon ESU

Map

Photos

Metrics

Metrics
  • C.0 Salmonid Habitat Restoration and AcquisitionY (Y/N)
    •      . . C.0.a Habitat restoration and acquisition funding 784,562.00
    •      . . C.0.b Length of stream treated/protected 1.00
    •      . . C.0.c
      Project identified in a Plan or Watershed Assessment
      National Marine Fisheries Service. 2017. ESA Recovery Plan for Snake River Spring/Summer Chinook Salmon (Oncorhynchus tshawytscha) & Snake River Basin Steelhead (Oncorhynchus mykiss).
    •      . . C.0.d.1 Project Monitoring (LOV)
    •      . . C.0.d.2 Monitoring Location (LOV)
    •      . . C.4 Instream Habitat ProjectY (Y/N)
      •      . . . . C.4.a Instream Habitat Funding 747,562.00
      •      . . . . C.4.b Total length of instream habitat treated 1.00
      •      . . . . C.4.c.1 Channel reconfiguration and connectivityY (Y/N)
        •      . . . . . . C.4.c.2 Type of change to channel configuration and connectivity (LOV)
        •      . . . . . . C.4.c.3 Miles of stream treated for channel reconfiguration and connectivity .65
        •      . . . . . . C.4.c.4 Miles of off-channel stream created through channel reconfiguration and connectivity .75
        •      . . . . . . C.4.c.5 Acres of off-channel or floodplain connected through channel reconfiguration and connectivity 12.3
        •      . . . . . . C.4.c.6 Instream pools created/added through channel reconfiguration and connectivity 17
      •      . . . . C.4.d.1 Channel structure placementY (Y/N)
        •      . . . . . . C.4.d.2 Material used for channel structure (LOV)
        •      . . . . . . C.4.d.3 Miles of stream treated through channel structure placement .50
        •      . . . . . . C.4.d.4 Acres of streambed treated through channel structure placement
        •      . . . . . . C.4.d.5 Pools expected to be created through channel structure placement 10
        •      . . . . . . C.4.d.6 Yards of average stream-width at mid-point of channel structure placement project (Yards)
        •      . . . . . . C.4.d.7 Number of structures placed in channel 38
      •      . . . . C.4.e.1 Streambank stabilization Y (Y/N)
        •      . . . . . . C.4.e.2 Material Used For Streambank Stabilization (LOV)
        •      . . . . . . C.4.e.3 Miles of streambank stabilized .20
      •      . . C.5 Riparian Habitat ProjectY (Y/N)
        •      . . . . C.5.a Riparian Habitat Funding 37,000.00
        •      . . . . C.5.b.1 Total riparian miles streambank treated 1.25
        •      . . . . C.5.b.2 Total Riparian Acres Treated 1.2
        •      . . . . C.5.c.1 Riparian plantingY (Y/N)
          •      . . . . . . C.5.c.2
            Species of plants planted in riparian
            Salix spp.; Populus trichocarpa
          •      . . . . . . C.5.c.3 Acres planted in riparian 1.2
          •      . . . . . . C.5.c.4 Miles of streambank treated with riparian planting 1.25
        •      . . . . C.5.d.1 FencingY (Y/N)
          •      . . . . . . C.5.d.2 Miles of fence along stream .16
          •      . . . . . . C.5.d.3 Acres of riparian area protected by fencing 15.0