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Instream Restoration Riparian Restoration Fish Passage
Flat Creek   Teton County, Wyoming
Primary Project Type: Instream Restoration
     Secondary Type: Instream Restoration
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  The Flat Creek project area is located in the Snake River drainage on the Nation...  

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Primary Problem: Sedimentation
     Secondary Problem: Over-Widened Channel
Main Restoration Action(s): Channel reconstruction, Habitat enhancement
Native Fish Focus: Snake River cutthroat
Is this project part of a watershed scale restoration? No
Project Dates: 1978 to 1994
  Initial Monitoring:
Restoration Implementation:
Follow-up Monitoring:
Lead Agency:
     Wyoming Game and Fish Department
Project Partners:
  Jackson Hole Chapter of Trout Unlimited
U.S. Fish and Wildlife Service
Jackson High School
Project Location: Flat Creek is located in the Snake River drainage on the National Elk Refuge approximately three miles north of Jackson, Wyoming. The 2.5 mile project area was upstream of Nowlin Creek and received supplemental flow from a transbasin diversion from the Gros Ventre River.
Project Description: During 1932-1966, water was diverted from the North Gap diversion canal into Flat Creek. Erosion problems within the canal led to sedimentation problems within Flat Creek. Massive sediment influx plugged riffles and filled pools with fine sediment, reducing trout spawning, nursery, rearing, and shelter areas in Flat Creek. An aqueduct was installed during 1966, but sediment remained a problem in the stream. By 1984 much of the stream was wide and shallow with silty substrate, little cover, and poor trout productivity. In addition, the Flat Creek project area meandered through a broad treeless meadow that contained limited riparian vegetation and few willows. Approximately 10,000 elk wintering on the National Elk Refuge impacted riparian areas and streambank stability.

Flat Creek was very popular with anglers and supported an estimated 1,900 angler days for wild Snake River cutthroat trout and brook trout in 1988. The fishery was noted for trophy Snake River cutthroat trout longer than 20 inches total length. Currently, the fishing season is 1 August to 31 October, angling is by artificial flies only, and the limit is one Snake River cutthroat over 20 inches per day.
Project Goals: The goals of this project were to improve fish habitat by stabilizing stream banks, improving fish cover, and narrowing and deepening the stream channel. A narrow channel with swifter flow was designed to encourage natural removal of fine sediments from stream riffles.
Project Methods: To curb sedimentation problems and improve fish habitat in Flat Creek, several different restoration activities were implemented between 1978 and 1987, including the installation of instream habitat structures and the use of a “riffle scrubber” to remove embedded fine sediment from the stream. Click here for more information.
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  Volunteers from Trout Unlimited constructed 167 skyhook bank cover panels for in...  
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  During 1984, Wyoming Game and Fish construction crews built 13 rock-filled woode...  
Monitoring Data and Collection Methods: Trout populations were monitored at two sites containing habitat improvement structures and at two untreated sites downstream from the habitat project. Evaluation was complicated by the downstream migration of trout after diversion water was shut off each year in early October. This problem was avoided by comparing fish samples taken only in September. Click here for more information.
Was this project effective and how was this determined? Installation of 20 deflectors, 1370 ft of tree revetments, 1336 ft of skyhook bank overhangs, 100 ft of rock riprap, a rock funnel, and excavation of several pools resulted in a narrowed stream channel, stabilized banks, increased trout cover, and deposition of excess sediment in bars and stream banks. Stream width was reduced 32% post-treatment. Snake River cutthroat trout clearly benefited from the improved habitat as both abundance (six-fold increase) and biomass (five-fold increase) were greater post-treatment. Trophy-size Snake River cutthroat abundance increased 43% post-treatment. Click here for more information.
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  (Before) Prior to restoration activities in Flat Creek, the stream channel was w...  
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  (After) Habitat improvement structures installed in Flat Creek created a narrowe...  
Confounding Effects/Additional Information: Skyhook bank overhangs installed in Flat Creek were designed simulate undercut banks and provide resting habitat for trout. During summer, however, flow under the overhang ledges was too swift to provide effective trout resting cover, and trout were not using the overhangs as anticipated. All skyhook devices subsequently were modified by intermittently placing large boulders under the overhang to slow flow and provide support for the overhang. High water flow also caused some damage to instream structures; some log deflectors suffered loss of center fill and cover ledges, some skyhook bank overhangs shifted due to backfill settling, some were inundated by gravel and fine sediment, and fill dirt covering some overhang ledges washed out. Repairs were made as necessary and the sediment trap was excavated again in 1990 to remove sediment accumulations.
Project Specs (all specs are estimates):
  Man Hours: Volunteer labor provided by Trout Unlimited (TU) and Jackson High School students.
Overall Estimated Cost: $79,070 ($30,410/mile): $37,910 from WGF, $32,160 from TU, and $9,000 from USFWS Additional notes: In Kind - In Kind: TU raised money to rent extra equipment and help pay project expenses, USFWS provided an Environmental Assessment, equipment, and manpower, and WGF provided project design, a 404 permit, equipment, manpower, project evaluation, and construction oversight. Trees and rocks were trucked to Flat Creek, whereas the other structures were built from lumber purchased locally.
For more information on this project contact:
  Allen Binns, Wyoming Game and Fish Department, Email:
This information was collected by: Michelle White
Project last updated on: 4/6/2007

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Updated: February 16, 2007
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