Oxbow Conservation Area Tailings Restoration Monitoring & Evaluation

This project gave funding support for the ongoing and planned monitoring related to the restoration of dredge mining impacts on the Oxbow Conservation Area on the Middle Fork John Day River. The project, known as Oxbow Tailings Restoration Project, is a multi-phase project, with Phases 1-5 now all completed. The monitoring from this project supported the Oxbow Tailings Monitoring and Maintenance Plan. The monitoring plan examined project effectiveness over time and following various flow events at 2-year and 5-year flows. The monitoring focused on physical habitat attributes, as well as plant survival and success.

Funding in this proposal supported salary and fringe for tribal staff to perform data collection. In the past survey-grade GPS equipment has been borrowed from other tribal programs, but with increases in restoration and other monitoring efforts, this equipment has been in higher and higher demand. Funds requested were also applied to the purchase of an additional survey-grade GPS (Topcon) to be part of this Oxbow program for continued work on this monitoring for the next ten years. The equipment will continue to be used for these monitoring sites, other monitoring efforts on past and future projects, and potentially for restoration implementation.

The Oxbow Tailings Monitoring and Maintenance Plan looks at six objectives with measurable elements for each:

Objective 1. Restore Natural Channel Form. Use reference and historical data to restore channels of the river and creeks to a form compatible with the hydrology and geomorphology of the system.

Objective 2. Reconnect the Floodplain. Connect river channel to floodplain to allow for frequent inundation to reduce high flow energy.

Objective 3. Increase Instream Habitat. Increase aquatic habitat complexity to create optimal habitat for salmonids.

Objective 4. Enhance the Riparian Vegetation. In order to holistically improve riparian and floodplain areas we must complement the physical, geomorphic restorative alterations with biological enhancements. Therefore we will intensively plant and protect riparian zones to enhance stream bank roughness, enhance stream shade, and recruit wood for streams.

Objective 5. Lower Stream Temperature. Remove bifurcated, dredged channel sections to reduce solar loading, and create conditions that favor hyporheic exchange and improved thermal refugia for salmonids.

Objective 6. Maintain Fish Passage. Employ measures in project design to avoid water seeping into dredge tailings or unconsolidated fill, which lowers in-channel flow and limits fish passage

To perform this work, field observation work will be performed either annually or following monitoring specific post-flow events (see Figure 1 from project proposal). Monitoring may continue for up to ten years following construction.

The project monitoring is complimented by an Intensively Monitored Watershed (IMW) program locally. The IMW has several partners engaged in geomorphology, water quality, water quantity, groundwater interactions, habitat, macroinvertebrates, and fish populations.

The monitoring will determine if this Oxbow tailing restoration project restores hydraulic and ecosystem processes for riparian and instream habitats critical for Mid-Columbia summer steelhead, spring Chinook salmon, and bull trout. This multi-phased project is located in the heart of spring Chinook salmon spawning, adult holding, and juvenile rearing. The property averages 14% of spring Chinook salmon spawning in this critical habitat zone of the MFJD watershed, but spawning is below site potential due to past dredging. This property is used by steelhead for both juvenile rearing and spawning in the river and five perennial tributaries within the property boundaries. The property has exceptional juvenile rearing potential, stemming from its location in the watershed and the six perennial tributaries entering the river within the property, but degraded habitat conditions limit current production. The Phases 2, 3, 4, and 5 Project sites restore connectivity to the river on Ruby Creek with channel construction and habitat enhancement of the lower 400-500 feet of the creek. Pacific lamprey are also present in the river and tributaries on this property.

The project primary goal is to 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 rearing habitat, as this is the main identified bottleneck in population recovery. Pools with large wood structure, complex riffles, and targeted use of cold-water alcoves and spring channels will be the features to aid in rearing habitat for salmonids. Water temperature will also be buffered through an extensive vegetation plan, which promotes stream shading and appropriate channel widths on the constructed channel segments.