Oxbow Dredge Tailings

Phases 1 and 2 of the Oxbow Tailings Restoration project were completed as designed. These funds were used specifically for implementation of the restoration design. CRITFC PCSRF funds paid partially for the transport and placement of 33 log structures on the river along a 1.06-mile stretch. The 33 structures created or enhanced 18 pools. OWEB funding (project #211-6027-8442) was used to help pay for all of the other project tasks.

Phase 1:
The main purpose of the Phase 1 project was to enhance instream habitat of the south channel and short reach of the river above the bifurcation. Channel structures will enhance habitat for fish. Treatments included (1)construction of large woody debris structures to scour pools and offer fish cover, (2) stream bank bio-engineering and structures to reduce erosion and initiate fast vegetative and woody plant recovery, (3) removal of artificial berm features present on the floodplain, (4) various point bar and floodplain tree placements to allow for future instream wood supply, reduce water energy on the floodplain during flooding, and offer riparian complexity, and (5) pool enhancement where appropriate.

The Bureau of Reclamation, through the US Forest Service TEAMS Enterprise, funded and produced the project design with a lot of input from the Tribes, and the Interdisciplinary Team (See Appendix A). The Design is too lengthy for this report. Large wood structures consisted of 32 structures sites and nine different designs to mimic natural wood jams using whole trees (including root wads). Most of the trees are buried into the bank following the engineered plan set for the project. The Tribes used 425 whole trees stockpiled on the property (donated by ODOT).

Stockpiled trees were placed on the property in 2010. As the two piles of trees were as far as 1.5 miles from some of the structure sites, transport during Phase 1 was a concern as most of the work site is on sensitive riparian ground. During the bid process the Tribes developed two bid options for transporting the tree to the site through use of trucking with rubber-tracked dump trucks, or with aerial helicopter operation. The helicopter was the preferred option, as even the low pressure impact of the rubber-tracked vehicles would impact vegetation and soils with the required number of trips.

Phase 2:
Phase 2 project target was to restore land forms altered by the dredging back to a condition similar to pre-mining disturbance. These actions include: (1)construction of about 1,000 feet of new channel for Granite Boulder Creek, (2) grading of tailings to restore topography to an alluvial fan condition and open up additional floodplain to the river, (3) removal of about 3,400 feet of the north channel ditch, (4) covering the tailings-composed surfaces with soil, (5) planting and seeding of the disturbed areas, and (5) fencing out the new channel to maximize plant growth that would otherwise be suppressed by ungulate browse.
The critical engineering component was the new Granite Boulder channel. This channel was constructed with riffle-pool-glide sequences that maximized habitat for salmonids. Plants were salvaged from the nearby north channel to jump-start riparian and instream habitat, and 2,800 containerized plants were planted along the new channel, supported by a sprinkler irrigation system to enhance rooting of the plants through the end of the growing season. The new channel’s riparian area was also seeded and mulched with straw to optimize growing conditions.

The Bureau of Reclamation funded and produced the project design through a contractor, the U.S. Forest Service TEAMS Enterprise. TEAMS were guided by a lot of input from the Tribes, Reclamation, and the Interdisciplinary Team formed to review the Tailings’ project designs. The design is too lengthy for this report but links to these materials are listed in Appendix A.

This project is located in the heart of spring Chinook salmon spawning, adult holding, and juvenile rearing. The property averages 13% of spring Chinook salmon spawning in this critical habitat zone of the MFJD watershed, but spawning is below site potential due to past dredging. The property exhibits marginal juvenile rearing stemming from its location in the watershed and the six perennial tributaries entering the river within the property, but is far below ecological potential due to degraded habitat conditions. The Project site will benefit connectivity to the river on three tributaries: Butte Creek, Granite Boulder Creek and Ruby Creek. All three creeks are use by steelhead for rearing and spawning. All three creeks are used by spring Chinook salmon for rearing. Pacific lamprey are present in all of these creeks, as well as the river.

The project will restore instream habitat conditions and structure for salmonid production, and set the stage for processes needed to sustain habitat features. This project seeks to greatly enhance instream habitat for salmonids in terms of holding cover and spawning gravel availability. The project seeks to reduce overall stream temperature through removal of a dredged channel bifurcation, which will reduce the solar exposure to the stream. Water temperature will be eventually buffered from an extensive vegetation plan which promotes stream shade and appropriate channel widths on the constructed channel segments.