This project consists of two components.  First, road #4660 was converted to Peavine Trail #1657 in 1992.  Many of the culverts left in place are plugged and at risk for failure. The existing road fill encroaches on the floodplain.  The proposed solution is to remove all the culverts and narrow the trail.  Second, in the 1980’s instream structures were installed in Chesnimnus and Elk Creeks.  These structures are causing the channel to widen and many are juvenile fish passage barriers.  The proposed solution is to remove the wire gabions and geotextile material associated with the structures and to modify the structures to restore stream form and function.  Anticipated partners are:  Wallowa Resources, USFS, Grande Ronde Model Watershed, BPA, OWEB, Title II, and National Forest Foundation.  BPA funds will be used for Wallowa Resources project management, Peavine culvert removal and instream structure modification in Elk and Chesnimnus Creeks.

The overall objective of the project is to improve riparian and stream conditions in Peavine, Elk and Chesnimnus Creeks in the Chesnimnus and Upper Joseph Creek (UJC) watersheds. This project was identified as a high priority restoration activity in the Upper Joseph Watershed Action Plan and continues implementation of project recommendations developed through the UJC Watershed Assessment (see www.wallowaresources.org/ujc_assessment).  The Chesnimnus Watershed was formerly part of the UJC Watershed, and for simplicity will be regarded as part of the UJC Watershed for the rest of this document.

The UJC Watershed has been identified as one of the five highest priority Geographic Areas for restoration for the Joseph Creek Steelhead population (Grande Ronde Subbasin Plan, p. 16).  This project would address the Key Limiting Factors of Key Habitat Quantity, Sediment, and Temperature.  The Peavine Trail conversion, by removing all existing culverts and narrowing the trail footprint, would accomplish several things: eliminate full-sized vehicle use; re-establish sediment transport and biologic and hydrologic connectivity in 6 intermittent tributaries to Peavine Creek; reduce the risk of culvert failures and concurrent sedimentation to steelhead spawning habitat; and, increase floodplain storage by pulling the roadbed farther away from the creek.

Instream structure modifications would eliminate chronic downstream bank erosion, allowing the channel to narrow there and potentially improve stream temperatures.  In addition, the instream structure modifications in Upper Chesnimnus Creek will address Problem 7 (Table 5-1, p. 32) where population connectivity is reduced as a result of structural barriers within specific watersheds.  Several log weirs in this creek block passage of juvenile steelhead during low flow.  The Plan also states that restoration in the UJC Watershed will have a large impact on Snake River Steelhead abundance and productivity (p. 17).  Instream structures (also called check-dams or log weirs) were installed in many of the Forest Service creeks in the mid - 1980s for two main purposes: 1) to slow stream incision and store sediment behind logs thereby locally aggrading the stream, and 2) to create scour pools and fish habitat in streams over-widened from a variety of current and historic management practices.  Instream structures were considered the best technology at that time and were installed with great fervor across the nation without regard to differences in channel morphology (stream type) or complete consideration of all hydraulic forces that would be at work around the structures.  

Each instream structure was created from a 30-60 ft. long, 1.0-2.5 ft. diameter log placed level and perpendicular to streamflow.  The ends of these logs were secured in place by burial in the banks and often had a large gabion basket placed on top of each end.  Wire mesh was placed on the streambed extending 3 ft. upstream from each log.  Geo-textile (waterproof) material was placed on top of the wire mesh and was stapled to the mesh and log to keep water flowing over, not under, the log structure.  Most structures were slightly notched in the middle with the intent of funneling water at low flows toward the middle of the creek downstream.

This is the third phase of a 3-Phase, or 3-year, effort to modify these instream structures and improve juvenile fish passage and hydrologic processes in the UJC watershed.  Phase I, completed in 2005, involved modifying 39 structures in Segments A and B of Chesnimnus Creek and 41 structures in Swamp Creek.  Phase II, completed in 2006, involved modifying 25 structures in Segment C of Chesnimnus Creek, 25 structures in Peavine Creek and 41 structures in Devils Run Creek.

This final phase, Phase III, will involve modifying 90 structures along 6.5 miles of Elk Creek to allow for appropriate channel form and function and 52 structures along 1.5 miles of Upper Chesnimnus Creek to allow for complete juvenile fish passage and appropriate channel form and function.

All components of this project were developed by USFS Hydrologist, Dana Orrick.  Technical advice for the instream structure modifications was provided by the Regional Aquatic Restoration Assistance Team and stream expert, Dave Rosgen.  Road decommissioning advice was provided by USFS Engineers, Jeff Stein and Stephane LaChance; USFS Recreation Manager, Rob Gump; and USFS Weed Manager, Leigh Dawson.