Oxbow Conservation Area Habitat Restoration Phase 6

Host to both mid-Columbia spring Chinook and ESA-listed summer steelhead, the Middle Fork John Day River is considered critical habitat for juvenile and adult anadromous salmonids. However, over the past several decades both species have experienced notable declines in population abundance within this region. Historically, the Oxbow Conservation Area (OCA) was heavily dredged for gold mining in the early 1940s. Previous project phases starting in 2014 have been completed in an effort to bring the system to an optimal condition. This included floodplain grading to level tailings, channel reconstruction to add sinuosity, complexity, and rearing habitat. Alongside these phases came floodplain, riparian, and wetland restoration.



Channel and instream habitat complexity, floodplain connection, and juvenile rearing are identified as major limiting factors for salmonid recovery in the Middle Fork. Rising water temperatures in the Middle Fork that verge on the upper thermal tolerances of Chinook and steelhead will only be exacerbated with climate change. The Oxbow Phase 6 project aims to address these limiting factors. The Phase 6 project focuses within the Ruby to Beaver Creek area of the OCA. This area shows high uplift potential by addressing the limiting factors of complexity, floodplain connection, rearing habitat, and floodplain/groundwater processes. Actions to do so in the design include floodplain grading, historic channel connection, new channel creations, installation of large woody debris, gravel augmentation, and planting. Since efforts to establish riparian vegetation to provide solar shading have been minimally successful in sections of the project footprint, floodplain grading and bank scalloping will be strategically placed to increase floodplain connection and raise the water table to encourage soil deposition and substrates suitable for riparian plant establishment. Side channel excavation will take place to reactivate old river scars and integrate previous phased alcoves into a flowing system with higher rearing suitability than demonstrated since their implementation. While initially designed to function as salmonid rearing habitat, the observed outcome has seen fish composition dominated by pikeminnow in those alcoves. To increase channel and instream habitat complexity, constructed riffles and point bars are designed to provide sediment and complexity suitable for spawning. Instream and floodplain roughness will also be incorporated through multiple large wood and vegetation-based structures. With the anticipated water table increase, the following riparian plantings are expected to have better chance of establishing along the south bank to reduce solar loading. The ultimate outcome is to have naturally functioning and self-sustaining floodplains and quality instream habitat for the CTWSRO to achieve healthy harvestable Chinook salmon and summer steelhead.



Worksite #1 Proposed Work:

Floodplain grading and bank scalloping will be strategically placed to increase floodplain connection and raise the water table to encourage soil deposition and substrates suitable for riparian plant establishment. Side channel excavation resulting in an estimated 0.38 miles will take place to reactivate old river scars and integrate previous phased alcoves into a flowing system with higher rearing suitability than demonstrates since their implementation. To increase channel and instream habitat complexity constructed riffles (~4) and point bars are designed to provide sediment and complexity suitable for spawning. Instream and floodplain roughness will also be incorporated through multiple large wood and vegetation-based structures (~135 wood structures, ~8 vegetated islands). Spawning gravels will be placed on ~.25 miles. With the anticipated water table increase riparian plantings that are also planned are expected to have better chance of establishing along the south bank to reduce solar loadi

With the current state of salmon and steelhead in the John Day River and the broader mid-Columbia River basin, restoration projects of this scale are increasingly necessary to preserve these populations of fish. Federal, non-profit, and state agencies across the basin have and continue to allocate time and resources to restoring the Middle Fork John Day. Much of this work has focused on the tributaries, which are highly important, especially for adult steelhead and rearing of all salmonid species. Yet, our data show that juveniles also spend much of their time in the main stem of the Middle Fork, highlighting the importance of its restoration. This work is vital in order to improve fish habitat and water quality within the watershed and will prove to be even more crucial in the face of a changing climate.



This project aims to improve rearing habitat conditions, habitat complexity, spawning conditions, and water quality. These would all directly improve the conditions necessary to sustain healthy salmonid populations within the Middle Fork John Day River.