Spring Valley Reservoir Flow Augmentation, Design

Salmonid Restoration Planning and Assessments

Restoration Planning And Coordination
Project ID009 23 CW
Recovery DomainsSnake River
Start Date11/29/2023
End Date10/31/2027
Year2023
StatusOngoing
Last Edited01/16/2025
 
1 - 1

Description    


The Idaho Department of Fish and Game (IDFG) will design a flow augmentation project for the Spring Valley Reservoir (SVR) Dam to restore perennial flow downstream to >18 km of Spring Valley and Little Bear creeks, within the Potlatch River watershed. Current habitat conditions include a flow-limited stream reach that exhibits a loss of perennial flow during summer months. Declines in streamflow also result in increased water temperatures and low dissolved oxygen levels, which further reduce available habitat and can result in fish kills. Loss of base flows during summer months is a primary factor limiting juvenile steelhead growth and survival in the Potlatch River basin in Northern Idaho.



Project actions for this proposal will be to develop engineering design plans to increase the height of Spring Valley Reservoir Dam 42” and the surface elevation of the reservoir by 36”, reconfiguring the spillway to meet safety standards, and replacing the current siphon valve with an automated valve that will allow for precise control of water released from the reservoir. The project will result in an increase in reservoir storage volume of 150 acre-ft. This additional capacity would allow for ~0.5 cfs of water to be released annually during summer and early fall months to restore perennial flow downstream of the reservoir. The result will be to increase habitat capacity and summer rearing habitat for juvenile steelhead in >18-km of stream.

Project Benefit    


The NOAA recovery plan for Snake River Basin steelhead (NMFS 2017) identified impaired fish passage, reduced stream complexity and channel structure, excess fine sediment, elevated summer water temperatures, diminished streamflow during critical periods, reduced floodplain connectivity and function, and degraded riparian conditions as the primary steelhead liming factors in this watershed. While previous projects in the Little Bear Creek drainage (PCSRF 010 11 CW; PCSRF 006 13 CW; PCSRF 004 11 CW; 014 13 CW: 014 16 CW) have focused on addressing passage barriers and improving habitat complexity, the SVR Flow Augmentation project will directly address the lack of perennial flow, lack of suitable habitat, increased summer water temperatures and decreased dissolved oxygen levels. This project will restore flow to >18 km of critical stream habitat for juvenile steelhead. Restoring natural river processes and function will directly increase habitat capacity, growth, and survival for juvenile steelhead. The impact of this project should be detectable as it is located in a tributary (Little Bear Creek) with some of the highest densities of steelhead in the Potlatch River Basin. Life cycle modeling suggests that this flow augmentation could increase steelhead smolt production by 2,500 smolts annually. As such, flow augmentation from Spring Valley Reservoir is vital to the survival and production of ESA-listed steelhead in Spring Valley and Little Bear creeks and potentially stream reaches further downstream. The completion of this project will also allow for future in-stream habitat restoration projects to be conducted in the rewetted stream reach, further improving steelhead habitat, growth, and survival.



This project will have additional benefits beyond improving steelhead habitat. Reconfiguring Spring Valley Reservoir dam will include reconstructing the spillway. The new spillway will be an overflow spillway which will be much safer, as it will no longer require IDFG employees to maintain dam boards to control the reservoir surface elevation. It will also be designed to handle larger flood events, which improves safety for the dam and downstream infrastructure. The in-reservoir infrastructure will also be improved as part of this project (funded by IDFG as match for construction phase), which will improve the reservoir fishery and recreational opportunities, and thus benefit local economies.

Accomplishments

Metric Completed Originally
Proposed

Funding Details

SourceFunds
Other$105,333
Report Total:$105,333


Project Map



Worksites

WS-1    


  • Worksite Identifier: WS-1
  • Start Date: 11/29/2023
  • End Date: 10/15/2026
Area Description

No Area Description data was found for this worksite.

Location Information

  • Basin: Clearwater (170603)
  • Subbasin: Clearwater (17060306)
  • Watershed: Big Bear Creek (1706030610)
  • Subwatershed: Little Bear Creek (170603061002)
  • State: Idaho
  • Recovery Domain: Snake River
  • Latitude: 46.78342
  • Longitude: -116.75269

ESU

  • Snake River Basin Steelhead DPS

Map

Photos

Metrics

Metrics
  • B.0 Salmonid Restoration Planning and AssessmentsY (Y/N)
    •      . . B.0.a Planning And Assessment Funding .00
    •      . . B.0.b.1 Area Encompassed
    •      . . B.0.b.2 Stream Miles Affected
    •      . . B.1 Restoration Planning And CoordinationY (Y/N)
      •      . . . . B.1.a Planning and Coordination funding
      •      . . . . B.1.b.11 Engineering/design work for restoration projectsY (Y/N)
        •      . . . . . . B.1.b.11.a
          Name of plan implemented
        •      . . . . . . B.1.b.11.b
          Description and scope of the plan implemented