Sub-Reach 1 Implementation, Lower Lemhi Rehabilitation Project

Salmonid Habitat Restoration and Acquisition

Instream Habitat Riparian Habitat
Project ID007 19 SA
Recovery DomainsInterior Columbia
Start Date12/01/2019
End Date10/31/2022
Year2019
StatusOngoing
Last Edited03/22/2022
 
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Description    


The project goal is to expand the current limited floodplain while creating substantial lateral side channel habitat with multiple complex structures. Project actions will include: 1) mechanically construct more than a mile of additional river channel, including mainstem and lateral channels to increase stream sinuosity, reduce channel slope and water velocities, increase lateral habitat, and increase pool/riffle ratios (creation of instream pools), 2) remove and/or relocate mechanically installed material and structures, such as rip rap, levees, ranch access roads, and irrigation diversions, 3) grade river banks and benches to establish a larger floodplain/riparian forest that will allow natural stream channel processes to occur, and 4) install engineered log jams and other woody debris structures (using unanchored and anchored logs and stumps with rootwads) throughout the existing and newly created stream channels to provide channel structure, roughness, and pools (created through structure placement), and 5) install native potted plants and seed in riparian and floodplain areas. Logs, revetments, and vegetation will be used to stabilize existing streambank. Spawning gravel will be placed in the newly constructed channels. This project includes funding for video documentation.

Project Benefit    


The goal of SR1 is to develop a more natural floodplain while restoring natural river processes and function. Project objectives identified to achieve this goal include extending and developing complexity in existing river channels, development of a substantially larger floodplain, and riparian zone restoration and protection. Currently, this reach lacks proper stream channel structure and function, instream structural complexity, the bed load consists of large homogenous substrate unsuitable for spawning, water velocities are very high, and there are no slow water or lateral habitats suitable for fish rearing and growth. As such, through the Lemhi Effectiveness Monitoring Program, we document low fish survival rates in this portion of the river. Project actions are expected to increase habitat capacity for key juvenile life stages that is currently limiting recovery of ESA listed fish throughout the Lemhi basin (Office of Species Conservation, 2019)



The condition and scale of SR1 will contribute substantially to improving freshwater productivity of Chinook salmon and steelhead in the lower Lemhi River. Unlike the other subreaches, bank elevations in SR1 are only slightly higher than the river surface, providing conditions sufficient for inundation of the floodplain during average water years. Thus, more cost efficient techniques can be applied to develop an active floodplain and anabranched complex river segment. A conceptual design previously developed includes more than 50 large wood structures, multiple side channels, a more sinuous mainstem river, and a considerably larger floodplain that will be managed for riparian health and function. Furthermore, relocation of an existing irrigation diversion will provide ample space to develop the proposed floodplain with good quality fish habitat throughout the entire sub-reach.

Accomplishments

Metric Completed Originally
Proposed
Instream Habitat
  Stream Miles Treated .51
Riparian Habitat
  Stream Miles Treated 2.72
  Acres Treated 6.6

Funding Details

SourceFunds
PCSRF$1,291,480
Other$417,467
Report Total:$1,708,947


Project Map



Worksites

WS-1    


  • Worksite Identifier: WS-1
  • Start Date: 12/01/2019
  • End Date: 12/01/2021
Area Description
SR1 Lemhi River

Location Information

  • Basin: Salmon
  • Subbasin:
  • Watershed:
  • Subwatershed:
  • State: Idaho
  • Recovery Domain: Interior Columbia
  • Latitude: 45.105167
  • Longitude: -113.732801

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.5 Acres of off-channel or floodplain connected 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.4 Acres of streambed treated through channel structure placement
        •      . . . . . . C.4.d.5 Pools expected to be created through channel structure placement
        •      . . . . . . 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
      •      . . . . 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.4.f.1 Spawning gravel placementY (Y/N)
        •      . . . . . . C.4.f.2 Miles of stream treated with addition of spawning gravel
        •      . . . . . . C.4.f.3 Cubic yards of spawning gravel placed (Cubic yards)
      •      . . 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