2003 Log-Jam River Restoration, Photo Taken in August 2005

Pioneer Park Restoration

The river restoration community has recently shifted toward more naturalized river restoration techniques, which forces us to rethink our riverbank designs.  In the 1980s and 90s, the river engineering community was challenged to shift away from tall riprap banks and concrete channels, toward lower-profile boulder structures that were more respectful of natural river morphology (Rosgen 1997, Fischenich, 2003).  Today, the river restoration community is being challenged to move away from boulder structures toward the use of coarse woody material (CWM) and live vegetation better mimicking natural riverbank structure (IECA 2003).  This evolution parallels our growing recognition the foundational role CWM plays in natural ecosystems.  It helps to maintain site productivity, stabilization, and biodiversity (Ministry of Forests 2005) and offers enhanced habitat value for aquatic, terrestrial, and avian wildlife.

The 2003 river restoration performed in Pioneer Park was permitted for the Town of Hot Sulphur Springs by the US Army Corps of Engineers in collaboration with Colorado Division of Wildlife, USDA Natural Resources Conservation Service, Grand County Planning and Zoning, Grand County Department of Natural Resources, and the East Grand School District.  In this situation, permitting and access constraints forced us to rethink our original design, which was a series of boulder-vane structures and a boulder bankfull bench.  The resultant design utilized wind-fall cottonwoods from within the park and combined them with local lodgepole pine to form a log-crib/bankfull bench.  The goal was to reduce near-bank water velocities with hydraulic coarseness rather than deflecting flows with boulders. 

Although our intermediate design called for regular “Lincoln Log” cribbing using 12” diameter logs, the field-fit structure evolved into a highly irregular, continuous riverbank assembly with 12-24” laterals laying parallel with river flows and > 24” log “dead men” buried into the bank parallel to the river.  The irregular cottonwoods offer both structural diversity and habitat complexity.  Both coarse and fine materials can be used to create spawning and rearing habitat for fish (BLM 2005).  As a result, the crib was stuffed with cottonwood slash and river cobble-gravel and topped with willow clumps and wetland sod (Figure 1). 

Larger-diameter downed trees have been shown to be integral design components because of their stability and durability (Bull 2002 in LCERP 2003); the longer pieces provide better runways and shelter for wildlife under suspended logs.  Large structures in streams create pools and pockets of still water where insect larvae develop and fish rest and hide from predators (Creighton 2000).  Monitoring in April 2005 documented excellent use of the installed CWM by both fish and invertebrates, which support other aquatic, terrestrial, and avian species. 

The 2003 riverbank restoration project is revegetating nicely and remains stable; however, upon reflection we see that our emphasis on bankfull and lower elevations is only half the restoration picture.  Our 2005 workplan aims to create a more complete riparian system.  Several levels will be constructed using a variety of sizes and decay classes, mimicking downed wood in order to conserve functional processes that foster sustainable riparian ecosystems (Torgersen and Bull 1995 in LCERP 2003).

The primary goal is to re-connect and foster the life cycle and food-chain components necessary for a large number of wildlife species by reintroducing CWM back into an expanded riverbank design with higher-level riparian habitat.  The CWM will decay slowly, increasing available nitrogen where plants are most likely to root.  Additional riparian vegetation will enhance our CWM structure with a natural rooted system.  These components provide essential habitat for small microorganisms that break down and ingest the CWM, and in turn feed aquatic invertebrates such as insects, spiders, slugs, and mollusks.  This prey base should, in combination with an enhanced fishery and better cover, considerably improve habitat quality for small and large mammals in the park, including beaver and river otter, as well as various avian species such as bald eagle, osprey, and Neotropical migratory songbirds.

References Cited

BLM 2005: Eugene Record of Decision, Fish Habitat.  Website accessed 2/24/05 http://www.edo.or.blm.gov/planning/rmp_rod/fish.html

Creighton, Janean 2000: Coarse Woody Debris: Tying the System Together. Northwest Woodlands Magazine, World Forestry Center. http://www.ccffa--oswa.org/Creighton.html  Website accessed 2/24/2005.

Fischenich, J. C. 2003: Effects of Riprap on Riverine and Riparian Ecosystems, ERDC/EL TR-03-4, U.S. Army Research and Development Center, Vicksburg, MS.

IECA 2003: Environmentally Sensitive Streambank Stabilization.  Professional Development Course Training Manual by John McCullah and Dr. David Derrick, International Erosion Control Association.  Steamboat Springs, CO.

LCERP 2003: Logan Creek Ecosystem Restoration Project: Final Environmental Impact Statement. Chapter 3: Snags and Downed Woody Material and Wildlife Habitat.

Ministry of Forests 2005: Forest Harvesting: Following Natures Land. British Columbia, CanadaWebsite accessed 2/24/05 http://www.for.gov.bc.ca/hfp/pubs/interest/forharv/fnltext.htm.

Rosgen 1996: Applied River Morphology, by Dave Rosgen.  Wildland Hydrology, Pagosa Springs, CO.

Rosgen 2003:  The Cross Vane, W-Weir, and J-Hook Vane Structures…Their Description, Design and Application for Stream Stabilization and River Restoration, by Dave Rosgen.  Wildland Hydrology, Pagosa Springs, CO

Grand Environmental Services, PO Box 857, Grand Lake CO.

Geoff Elliott, Principle Earth Scientist gelliott@rkymtnhi.com 970.627.5464

Corie Schott, Associate Wildlife Scientist cschott@rkymtnhi.com 970.531.2453

Profile posted on: September 7, 2005