Confederated Tribes of Warm Springs, John Day Basin Office
Confederated Tribes of Warm Springs, Oregon Watershed
Enhancement Board, Bureau of Reclamation, The Nature Conservancy, US
Fish and Wildlife Service, Grant County Soil and Water Conservation
District, Iron Triangle Construction, Chad Engle Construction, and the
North Fork John Day Watershed Council
The Dunstan Low Flow Enhancement Project was installed in the Middle Fork John Day River in the summer of 2015, and had 3 main objectives:
- Increase number and availability of complex aquatic habitats
- Re-establish floodplain process and function
- Increase high water and off-channel rearing habitat availability for juvenile salmonids
During the course of construction, 22 log structures were placed over 1.3 miles in the Middle Fork John Day River on land owned by The Nature Conservancy. All of the trees used for the project came from adjacent upslope areas of the property. Trees were individually selected to promote healthy stand function and process, and a majority of the trees were collected with root balls intact for ballast and additional aquatic habitat complexity. The log structures were placed with these objectives:
- Increasing water surface elevations in key areas of channel morphology
- Scouring pools to promote juvenile rearing and adult hold-over habitats
- Re-directing flows at high water to promote active channel process and function
To re-connect lost floodplain and side channel connectivity, inlets and outlets of 2 historic side channels were excavated to prolong wetted connectivity with the main channel. In addition, 20 artificial rock barbs were removed throughout the project, and 450+ linear feet of riprap was removed from 2 large areas of the main channel. Some of this material was added to existing riffles and glides to help raise the level of spawning gravels and to promote channel complexity. Native riparian plantings were installed throughout the project to promote riparian health and function. An Oregon Youth Conservation Crew assisted with slash installation in the wood structures, and placing straw and erosion control fabric throughout the project.
Post-implementation monitoring of the project found:
- Pool area increased by 213%.
- Glide area decreased by 81%.
- Width-to-depth ratio decreased by 36%.
- Approximately 1,900m2 of side channel habitat was reactivated.
- Large wood volume increased by 200%.
- The total number of habitat units in the reach increased by 48%.
Top photos: Before and after rip-rap removal.