Contract Description:
The restoration action was identified collaboratively during the development of the Upper Grande Ronde Atlas within a high priority Tier 1 node Subwatershed UGR 16.
The Lower Fly Restoration Project is located on Fly Creek, tributary to the Grande Ronde River. The project is located on 3.5 miles of Fly Creek (RM .5 -4.0). This project involves implementing restoration to improve habitat for listed spring/summer chinook and summer steelhead. The project is located in the Lower Fly Creek Subwatershed (170601040108) (T 4S, 35E, S 23, 27 & 34 and T 4S, R 35E, S 1, 12 & 13). Fly Creek is spawning and rearing habitat for Snake River Basin summer steelhead and redband trout and rearing habitat for Snake River Basin spring chinook salmon. Historic beaver trapping, roading, timber harvest, grazing and splash dams created a confined channel, with limited floodplain interaction. The project would prioritize LWD placement to add roughness, increase floodplain interaction and habitat complexity, and promote out of channel flooding. It is expected that the project will promote longer periods of hydrologic production, decreased stream temperatures, increased low velocity habitat, and increased fish cover. The project would place wood within 3.5 miles of Fly Creek and 9,500 seedlings will be planted. Project partners include: Grande Ronde Model Watershed, Bonneville Power Administration, and the US Forest Service.
Sub-problem 1 - Floodplain form and function
The Lower Fly Creek reach has limited water capture and retention capacities due to past anthropogenic influences. These deficiencies have lowered groundwater tables. This has resulted in a decreased ability to store water and buffer water temperature, less connection to the floodplain to moderate in-channel velocity, and lower quality fish habitat. Lack of floodplain form and function has resulted in:
• Potential increase of in-stream water temperatures from decrease in groundwater recharge, which can be problematic for salmonids.
• Increase of in-channel velocity where the channel has downcut, and doesn't spread water out onto the floodplain during high flows. The process of downcutting causes vertical erosion, which increases fine sediment levels and decreases habitat complexity.
• Decrease in the amount of zero velocity habitat, which provide juvenile salmonids protection, temperature buffering, food sources and feeding areas, and resting areas.
Sub-problem 2 - Side channel habitat and activation:
There are old channel scrolls within the floodplain that are rarely activated, due to many of the issues identified in Sub-problem 1.
• Channel incision and lack of woody debris have isolated side channel scrolls from the existing channel. These channels only flow during high flow events.
Sub-problem 3 - Fish habitat complexity:
The Lower Fly Creek fish habitat complexity (cover, pool quality/quantity, and zero velocity habitat) is limited.
• Channel incision and lack of instream woody material has affected the quantity and quality of spawning, rearing, and overwintering habitat in the Lower Fly Creek Reach.