Abstract: Closing Plenary Session  10:15 am (BACK)

Incorporating Ecological Criteria on a Large Scale Restoration Using the Natural Channel Design Approach 

Dave Rosgen, PhD
Wildland Hydrology
Fort Collins, CO

A large scale restoration project was designed and implemented in Central Idaho that incorporated multiple ecological objectives utilizing the Natural Channel Design approach.  Ecological criteria were established based on a limiting factor analysis for various organisms and their habitats, including large mammals, eagles, heron, waterfowl, songbirds and aquatic organisms.  The watershed assessment also documented the major causes of river and riparian impairment.  Land uses related to heavy long-term, season-long livestock grazing, poor irrigation practices, and direct channel impacts were responsible for the loss of physical and biological function.

The multiple objectives were to offset the limiting factors identified in the assessment phase; redirect land use practices to take care of the cause of impairment; reduce excess sediment from streambank erosion for both large and small streams; reduce water temperature; and convert the irrigation system from surfacing flooding to subterranean.  Thirteen miles of stream channels were constructed on a previously abandoned surface to reconnect floodplains and to regain an instream flow regime with a new water management plan.  The stream channel restoration included placement of gravel/cobble substrate and screened spawning gravels in glide bed features.  Materials were obtained from the excavation of oxbow lakes.  Toe wood was installed for streambank stabilization and instream cover for a wild trout fishery.  In addition to the oxbow lakes, emergent wetlands and off-channel food plots and fish rearing habitat were created.  On an adjacent large braided river (Big Wood), toe wood structures were implemented to reduce the excess streambank erosion and to improve fish habitat.  Overall, a great diversity of habitats were created for mammals, birds, and aquatics, including adult, rearing, reproduction, food chains, and low flow, high flow and winter refugia.  Invasive species were eliminated and native riparian vegetation was re-established on previously overgrazed lands including compatible overstory and understory species.  A grazing plan was included to prevent the recurrence of historic impairment and to provide winter range forage of big game.

Pre-calibration, active construction and post-restoration monitoring was conducted for streamflows, water temperature, ground water levels, turbidity, fish populations, food chains, and direct observation documentation of nesting eagles, herons and big game animal numbers and seasons including moose, elk, deer and antelope that reside and migrate through the property.  Monitoring will continue for several years to determine restoration effectiveness.