Project Goals

1.    Restore ecological processes that maintain a healthy, diverse, and resilient ecosystem to the project area by increasing the area of floodplain inundation at base flow conditions and surface roughness elements.
a.    Lower selected floodplain terrace areas to elevations conducive to more frequent inundation by removing floodplain fill material.  
b.    Increase floodplain and side channel connectivity by utilizing removed floodplain fill material to aggrade incised side channel.
c.    Encourage the development of complex and dynamic habitat and by increasing large wood frequency throughout the project area, including within the floodplain.
d.    Establish a diverse native plant assemblage in selected disturbed areas (long term goal, not funded by BPA).
2.    Increase low-gradient stream flow (maximize wetted surface) area to maximize off-channel rearing habitat for Upper Willamette River spring Chinook, Upper Willamette River rainbow trout, Pacific lamprey, and other species benefiting from these conditions.
3.    Create a complex, dynamic habitat that includes topographic diversity that can be utilized by native turtles (Western Pond, Painted) and other species.
4.    Remove stresses that could threaten goals stated above
a.    Remove man-made barriers (e.g. road, culverts, and large overburden piles that remain from the mining activities that occurred.  Removal of road and culverts is a long term part of the project and not funded under this BPA contract)
b.    Manage invasive plant species, and establish plantings of native emergent, riparian, and upland plantings that enhance aquatic and terrestrial habitats. While invasive species control and vegetation management are a long term part of this project, BPA funding will not be used for this work.

Back ground and context:
The Project will address the loss of floodplain connectivity and associated natural process caused by changes in land use and stream-side construction, hardening of the banks, and the placement of infrastructure within the floodplain can disrupt hydrologic processes. Revetments and infrastructure can facilitate the creation of single-thread streams where multi-breaded streams were more prevalent. Single-thread channels increase the systems transport capacity and reduce the supply and storage of wood, sediment and nutrients. Simplified and constrained channels also increase channelization, further reducing floodplain connectivity and the amount of available off-channel and high flow refuge habitat. Bathymetry of the primary Finn Rock Reach (FRR) side channel completed in 2018 shows that it is incising below the roads and infrastructure constructed in the 1960’s in order to extract gravel from the floodplain. The removal of large berms surrounding the gravel pits and associated roads and use of that material to aggrade incised channels and other surfaces will address the one of the root causes of the loss of floodplain connectivity at the FRR property. The project will also address the problem of decreased in-stream habitat complexity caused by a lack of large wood. The McKenzie River sub-basin, like many in the Willamette Basin, is largely devoid of the large woody debris that would have characterized the basin prior to European settlement. The lack of instream wood has reduced the frequency of deep pools, the amount of complex cover, and limited the storage of sediment within the McKenzie River. These changes have impacted spring Chinook salmon, bull trout and many other native species that depend on complex riverine habitats. The addition of 2300 pieces of large wood throughout the 70 acre project area will help facilitate the natural processes of gravel, sediment, and nutrient deposition that has been lost due to the removal of instream wood, originally to enable the transport of harvested logs downstream. Currently, removal of wood in the mainstem is carried out to allow for safe recreational use. While this side channel is not currently known to be used for recreation, it was formerly the mainstem of the McKenzie River. Historic aerials show that the side channel was the mainstem by 1936 before it shifted to its current location through a series of events between 1954 and 1972. Prior to these avulsions, the side channel would have been kept clear of large woody debris.

On the Project site, multiple land management practices negatively impacted floodplain habitat. In the late 1960s or early 1970s, the interior of the site was converted to an approximately 13-acre gravel extraction quarry (See historic aerials ). The mining activities included the installation of a number of berms and/or overburden areas intended to isolate the gravel pits. The placement of the overburden has contributed to the channelization of the McKenzie River and prevented the river from accessing the floodplain on the FRR property. An access road was constructed to facilitate this mining activity (See photos 5,6).  

This access road contained culverts, but largely blocked the flow of side channel, with fine sediments accreting upstream of the road and gravels and cobbles dominating the substrate below the road. Above the road is complex of wetlands with much higher sediment loading. The side channel is a multi-braided low velocity stream above the road and a single channel, higher velocity channel below the road. It is likely that this road has contributed to the process of head cutting of the side channel downstream of the road. This road partially washed away after mining had ended and left the side channel to continue the incision process up to this point. This partial washout left two culverts perched in the channel.  Addressing the access road and culverts is a long term part of the project and not occurring under this BPA contract.

Bare earth and bathymetric LiDAR show that many of the networks of complex channels now completely cutoff from the river. With the dams reducing flood frequency and intensity and a lack of inputs of large wood, gravels, sediments, and nutrients, the native salmonids and other native fishes have scant ability to access these formerly rich juvenile rearing and high-water refugia. The general lack of side channels, alcoves, and overall complexity has also constrained adult salmonids from accessing suitable locations for digging redds and successfully spawning. This project, presents an enormous opportunity to re-establish properly functioning floodplain.

The project design will identify several “leave islands”, areas where the existing grade and native vegetation will be allowed to remain in place. Leave island placement will maximize screening for neighboring properties and the protection of nesting locations for Western Pond and Western Painted Turtle habitat, with consultation from ODFW biologists determining the location and the sloping of the sides of the leave islands. Turtles require stable ground that remains 3-5 feet above ordinary high water (OHW) during the winter for at least one season to enable successful nesting).