PROJECTS > Mountain Creek
Mountain Creek Habitat – Irrigation
Location
Mitchell, OR
Total Cost
$1,700,000
Project Partners
- Landowners (2)
- Oregon Watershed Enhancement Board
- U. S. Fish and Wildlife Service
- Oregon Department of Fish and Wildlife
- Wheeler Soil and Water Conservation District
- Confederated Tribes of the Warm Springs
- Natural Resource Conservation Service
- Bonneville Power Administration
Project Elements
- Flood Control
- Historic Channel Reactivation
- Large Wood Placement
- Floodplain Reactivation
- Bridge Installation
- Riparian Fencing
- Riparian Planting
- Bank Stabilization
RSI Involvement
- Funding Acquisition
- Hydraulic and Hydrologic Modeling
- In-stream and Bridge Survey and Design
- Permitting
- Riparian Planting Implementation
- Partners Coordination
Project Description
This project was a multi-year multi-phase endeavor with the end goal of re-engaging 3.5 miles of historic channel of Mountain Creek and improving the landowner’s ability to irrigate 300 acres of meadow fields. The stream had been diverted into a bypass channel to avoid flooding issues in the low meadow areas but over time had created an incised channel that de-watered during the summer months with the sub-surface flow migrating back into the historic channel effectively creating a passage barrier to all aquatic species. Hydraulic and hydrologic modeling was used to develop inundation levels and determine maximum allowable flow through the historic channel. The irrigation system incorporated 36,000 ft of PVC irrigation pipeline with multiple control valves and spurlines to allow for efficient flood irrigation of the meadow fields. All phases of this project were completed within budget.
All four phases of the project included stream restoration and habitat creation which include; large wood placement, bank pullbacks, side-channel activation, and bridge installation. The landowner did the bulk of the work as his in-kind. RSI coordinated closely with the landowner on the construction and the resulting work has been toured and filmed by multiple agencies including USFWS.
The reactivation of the 3.5 miles of historic channel was accomplished in the summer of 2015. To alleviate the landowner’s concern that the re-engaged channel would create flooding issues, a structure was placed at the diversion point to divert water from the bypass channel into the historic channel. This structure allowed excess flow to be directed down the bypass channel during high flow events, but during normal operation the entirety of the flow will be directed down the historic channel. RSI was responsible for the design and modeling of the structure. Given the site constraints and the landowner concerns, RSI was required to design a complex structure that would allow a disproportionate amount of the high flow event to use the bypass channel and as such limit the amount of flow the landowner’s infrastructure would experience at higher events. This resulted in a complex dual weir design with a fish passage ladder incorporated into the structure.