Restoration of the Yankee Fork Salmon River

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Restoration of the Yankee Fork Salmon River

• Sponsored by
• Shoshone-Bannock Tribes (Jeff Anderson)
• Idaho Department of Fish and Game (Tom Curet)
• USDA Forest Service (Kerry Overton Tom Montoya)
• University of Idaho (John Buffington Peter
  Goodwin)

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Statement of the problem

• Snake River chinook salmon, steelhead, and bull
  trout have been listed under the Endangered
  Species Act as threatened, and westslope
  cutthroat trout are a Forest Service Sensitive
  Species.

• Severe population decline of Snake River Chinook
  salmon has resulted from hydropower operations on
  the Columbia and Snake Rivers (CBFWA 1991),
  overharvest, introduction of exotics and hatchery
  fishes, and habitat degradation (Nehlsen et al.
  1991).

• Until passage problems are resolved, the
  resiliency and persistence of remaining wild
  salmon stocks will be largely dependent on the
  quality and diversity of remaining stream
  habitats (Lee et al. 1997).

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Yankee Fork

• Historic records indicate that the Yankee Fork of
  the Salmon River was a particularly productive
  subbasin for salmonids (Overton et al. 1999) and
  has been classified as critical habitat for
  chinook and steelhead (57 FR 14653 62 FR 111).

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Dredge mining

• A 6 mile reach of the mainstem Yankee Fork has
  been severely altered by dredge mining.
• The dredged reach has been straightened,
  simplified, and isolated from its floodplain and
  is no longer capable of supporting a naturally
  functioning riverine ecosystem, and has been
  identified in Section 4.4.1.a of the Salmon
  Subbasin Summary as a major limiting factor.

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Limiting factors
The dredged reach limits the productivity and
biological function of the basin by reducing and
degrading the available

• Rearing habitat
• Spawning habitat
• Spatial connectivity of quality habitat

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1. Rearing habitat

• Wide shallow flow, lack of riparian shading, and
  lack of bed and bank irregularities create
  temperature extremes that inhibit growth and
  survival during rearing.

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1. Rearing habitat cont.

• Simplified channel form in the dredged reach also
  creates high velocities and a lack of hiding
  places (undercut banks, pools, etc.) which likely
  decrease survival during rearing.

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2. Spawning Habitat
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What limits spawning habitat?

• Lack of adult holding areas due to simplified
  channel morphology (lack of pools) and high
  velocities.

Simplified morphology, high velocities, and
extreme temperatures also may decrease survival
to emergence and successful rearing, thereby
decreasing the number of return spawners to the
dredged reach.
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Sediment supply
Lowering of the channel base-level during dredge
mining has destabilized side slopes adjacent to
the channel and may have initiated knick-point
propagation (channel incision) along Yankee Fork
tributaries.

• These processes may have elevated sediment loads,
  possibly degrading spawning and rearing habitat.

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3. Spatial connectivity
The dredged reach fragments the remaining quality
habitat in the basin (Overton et al. 1999).
Recent studies indicate that linkages between
salmonid populations and spatial distribution of
habitats may be a crucial component of ecosystem
health and basin viability (Rieman and Dunham
2000).
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• The valley slope, position within the watershed,
  and historic records indicate that the dredged
  reach was probably prime rearing and spawning
  habitat in an otherwise steep, mountain drainage
  basin. Consequently, the dredge mining
  effectively removed a significant portion of an
  already limited amount of salmonid habitat within
  the Yankee Fork basin.

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Restoration

• A multi-year restoration plan is proposed to
  reclaim the historic spawning and rearing habitat
  within the dredged reach and to reconnect the
  remaining quality habitat, thereby increasing the
  biological integrity of the basin.
• Identify physical and biological linkages to
  better define restoration actions and potential.
• Examine the larger spatial and temporal watershed
  processes and conduct restoration that is likely
  to be successful given the imposed watershed
  conditions.

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• The restored channel is expected to have a
  pool-riffle morphology, narrower width-to-depth
  ratio, and a functioning floodplain and riparian
  zone.
• These qualities should increase spawning and
  rearing success by reducing velocities, reducing
  excessive sediment transport and bed scour,
  reducing temperature extremes, increasing channel
  complexity, increasing oxygenation of buried
  embryos, and minimizing fine sediment deposition
  within the channel.

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Restoration Approach

• Pre-restoration study and design
• Phased restoration, allowing iterative
  improvement of methods
• Long-term physical and biological monitoring

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Pre-restoration Study and Design

• Successful channel restoration requires a clear
  understanding of current watershed conditions,
  how they differ from those of the past, what the
  desired future conditions are, and how the
  channel is likely to respond to restoration
  activity.
• Here, we seek to quantify past and current
  physical and biological conditions to provide a
  baseline for restoration activities and to
  provide data necessary to develop restoration
  options and designs.

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Existing Data

• Habitat and spawning surveys since the 1930s
• Pilot watershed analysis related to Chinook
  salmon
• Quantification of current and past hydrologic and
  geomorphic conditions

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Data Gaps

• Completion of aerial photography analysis of
  historic conditions
• Development of spatial coverages (GIS) of
  existing and historic stream riparian area,
  channel condition, and floodplain
• Geomorphic watershed analysis, including
  basin-wide assessment of channel morphology,
  physical process domains, and sediment budget
  (sources, magnitudes, and routing of sediment)

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Restoration Design

• Design criteria
• Create a naturally-functioning channel and
  riparian zone
• Methods
• Develop regional reference reaches, hydraulic
  geometry relationships, and regime diagrams
  (predictions of stable channel form) to provide
  initial guidance on channel morphology
• Use hydrodynamic models to predict flow and
  sediment transport within the channel and across
  the floodplain for a range of typical discharges
• Quantify hyporheic processes and the interaction
  of shallow groundwater with the channel and
  floodplain

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Restoration Design

• Maximize aquatic habitat
• Methods
• Use hydrodynamic models to rank potential aquatic
  habitat for different design options as a
  function of temperature, velocity, substrate
  size, and flow depth
• Conduct laboratory studies to examine
  interactions between proposed channel morphology,
  surface and intergravel flow, and consequent
  aquatic habitat. Maximize intergravel
  oxygenation of buried salmonid embryos, and
  minimize sedimentation and deposition of fine
  particle sizes within potential spawning sites.

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Phased Restoration

• Restore natural channel characteristics and
  floodplain function
• Grade, redistribute, and/or remove dredge spoils
• Construct new channel(s) and cross-section
  alignment
• Install restoration features (wood debris,
  bioengineered banks, etc.)
• Restore riparian plant communities
• Plant seedlings, transplant trees/shrubs
• Install erosion control fabric and seed
• Improve design and implementation based on
  results of concurrent monitoring

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Physical and Biological Monitoring

• Factors to be monitored
• Aquatic habitat, fish usage, and species
  abundance (Platts et al. 1983 Overton et al.
  1995 1997)
• Water quality (toxins and bio-accumulation of
  heavy metals)
• Stream temperature
• Surface and subsurface sediment size (Church et
  al. 1987 Bunte and Abt 2001)
• Channel topography and plan form
• Hydraulic discharge (Nolan et al. 1998)
• Sediment transport (Emmett 1980)
• Riparian vegetation
• Shallow groundwater and hyporheic processes

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Restoration Performance

• Conduct statistical analyses of changes in
  physical and biological conditions
• Compare different techniques for restoration
  implementation in terms of their success, cost,
  and time involved in implementation

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Knowledge Transfer

• Involve local high schools in data collection and
  restoration activities
• Participate in community and stakeholder meetings
  
• Develop agency reports
• Author and present study results at scientific
  conferences and in peer-review publications

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Expected Outcomes

• A naturally-functioning riverine ecosystem
• Improved spawning and rearing habitat
• Reconnection of fragmented habitat and increased
  biological integrity of the basin

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Questions?