Sub-Reach 1 Implementation, Phase 3, Lower Lemhi Rehabilitation Project

Salmonid Habitat Restoration and Acquisition

Instream Habitat Riparian Habitat
Project ID009 21 SA
Recovery DomainsInterior Columbia
Start Date12/09/2021
End Date10/31/2023
Year2021
StatusNew
Last Edited02/22/2022
 
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Description    


The Idaho Department of Fish and Game (IDFG) will implement Phase 3 of the Sub-reach 1 (SR1) project that is contained within the 2.2 mile contiguous Lower Lemhi River Rehabilitation Reach. SR1 is one of 4 sub-reaches in approx. 1.25 miles previously identified for aggressive channel and floodplain rehabilitation. Due to its relatively large scale, SR1 was further partitioned into four project phases. Phase 1 was constructed in 2021, Phase 2 construction commenced in October 2021 and is ongoing.



The Phase 3 project goal is to spatially expand the current floodplain while improving natural river processes, building upon previous SR1 phases. Implemented habitat treatments will include constructing multiple side channels, a more sinuous mainstem river, more complex instream habitat in the form of large woody debris and pools, and a more functional riparian zone. Removal of levees and grading the existing floodplain in combination with raising the surface height of the river and constructing side channels, will allow for lateral inundation from floodwaters at annual intervals. This will improve habitat diversity and complexity by allowing more natural processes to evolve. To further improve instream habitat, an existing ford will be replaced by a pre-fabricated bridge to eliminate open water crossings that transport equipment and livestock (captured in riparian metrics under water gap/livestock bridge). The project will install fencing to remain in place for 3-5 years until vegetation grows above browse height; due to the temporary nature, fencing metrics have not been included.

Project Benefit    


Development of a large active floodplain will substantially increase habitat capacity for critical juvenile life stages of Chinook salmon and steelhead. The project reach lacks proper stream channel structure, substrate consists of large cobble unsuitable for spawning, water velocities are high, and slow water or lateral habitats that are optimal for fish rearing and growth are limited. Project actions will address this condition and provide habitat complexity for key juvenile life stages that is currently limiting recovery of ESA listed fish

throughout the Lemhi basin.



Increased habitat capacity at the scale of Sub-reach 1 (SR1) is expected to improve Chinook salmon and steelhead freshwater productivity throughout the Lemhi watershed. Proposed aggressive habitat treatments will create hydraulic and structural habitat diversity in the lower Lemhi River, resulting in increases in fish abundance and survival. Lemhi Effectiveness Monitoring studies documents low overwintering fish survival rates in this portion of the river. Project actions are expected to substantially improve conditions for this critical juvenile life stage, with more juveniles surviving and leaving the Lemhi River sub-basin in better condition per each adult that enters the system to spawn.

Accomplishments

Metric Completed Originally
Proposed
Instream Habitat
  Stream Miles Treated 1.12
Riparian Habitat
  Stream Miles Treated 1.12
  Acres Treated 18.4

Funding Details

SourceFunds
PCSRF$1,478,409
Other$490,857
Report Total:$1,969,266


Project Map



Worksites

SR1 P3 Lemhi River    


  • Worksite Identifier: SR1 P3 Lemhi River
  • Start Date: 01/01/2022
  • End Date: 10/31/2023
Area Description

No Area Description data was found for this worksite.

Location Information

  • Basin: Salmon
  • Subbasin:
  • Watershed:
  • Subwatershed:
  • State: Idaho
  • Recovery Domain: Interior Columbia
  • Latitude: 45.107742
  • Longitude: -113.739804

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 .00
    •      . . C.0.b Length of stream treated/protected
    •      . . C.0.c
      Project identified in a Plan or Watershed Assessment
    •      . . 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
      •      . . . . C.4.b Total length of instream habitat treated
      •      . . . . 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
        •      . . . . . . C.4.c.4 Miles of off-channel stream created through channel reconfiguration and connectivity
        •      . . . . . . C.4.c.6 Instream pools created/added through channel reconfiguration and connectivity
      •      . . . . 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
        •      . . . . . . C.4.d.5 Pools expected to be created through channel structure placement
        •      . . . . . . C.4.d.7 Number of structures placed in channel
      •      . . . . 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
      •      . . C.5 Riparian Habitat ProjectY (Y/N)
        •      . . . . C.5.a Riparian Habitat Funding
        •      . . . . C.5.b.1 Total riparian miles streambank treated
        •      . . . . C.5.b.2 Total Riparian Acres Treated
        •      . . . . C.5.c.1 Riparian plantingY (Y/N)
          •      . . . . . . C.5.c.2
            Species of plants planted in riparian
          •      . . . . . . C.5.c.3 Acres planted in riparian
          •      . . . . . . C.5.c.4 Miles of streambank treated with riparian planting
        •      . . . . C.5.f.1 Water gap developmentY (Y/N)
          •      . . . . . . C.5.f.2 Number of water gap installations
          •      . . . . . . C.5.f.3 Miles of streambank protected by water gap development