Tourmaline Habitats Meadow Restoration Project

The Tourmaline Habitats Meadow Restoration project reconnected 49 acres of floodplain and treated 1.51 stream miles on the Middle Fork Big Bear Creek, a tributary to the Potlatch River in Latah County, ID. The project restored hydrologic and channel-forming processes and reestablished riparian vegetation. The project addressed the primary limiting factors for steelhead in the Big Bear Creek subwatershed in the project area by enhancing stream summer baseflows, maintaining cool stream temperatures, and reducing fine sediment delivery.

To achieve these goals and objectives, flow was removed from the straightened and incised channel and placed into the more sinuous historic alignment. Beaver dam analogs (reported as ‘other engineered structures’) and log habitat structures were utilized to create scour pools, slow flow, capture debris, increase floodplain access, increase habitat complexity, reduce sedimentation, and promote riparian vegetation growth. Berms and ditches that impeded the stream from accessing its floodplain were removed. The inactivated channels were filled/plugged with a series of earthen dams which created a series of wetland cells and increased hydraulic complexity. Decommissioning a landowner access road and berm removal further enhanced floodplain access. The landowner adjusted their livestock management plans to protect the new project area by excluding livestock from their rotation throughout the project area for a minimum of 3 years following project implementation. The project area was further protected from open range livestock access through fence maintenance and enhanced communication with the lessee. One low-water crossing was installed to allow for future livestock crossing and landowner access. Revegetation efforts utilizing native plant materials enhanced protection for new structures, reduced sedimentation, promoted future shade and future wood recruitment, and reduced invasive weed spread.

This project completed an increase amendment to complete adaptive management following significant winter and late spring high flow events in 2022. Additional BDAs were installed, floodplain wood was increased in vulnerable areas to prevent flow path development, slow overland flow, and increase infiltration, and persuasion channels were increased/extended to further reactivate floodplain during high flow events.

Metrics for the culvert and road decommission were missed in the proposed metrics. They have been included in final metrics.

Two primary limiting factors for ESA-listed steelhead in the Big Bear Creek subwatershed are low summer baseflow and high summer stream temperatures. This project addresses these limiting factors by improving floodplain connectivity and increasing channel complexity. Removing flow from the straightened ditch and into the historic channel alignment will increase flooding and rehydrate the meadow. Increased groundwater infiltration will enhance the quantity of cold, clean water later in the summer through groundwater discharge. Revegetation efforts will promote shade to maintain cooler temperatures through the summer. Enhancement of summer flows is beneficial for steelhead in a system where steelhead rearing is limited by low summer baseflow. Density dependence has been well documented in the Big Bear Creek subwatershed and is attributed to a lack of late summer rearing habitat due to low summer baseflows. The lower Potlatch River and associated tributaries, including Big Bear Creek, are flow-limited by mid- to late-summer, and increases in stream discharge will have significant positive effects on steelhead production.