Castle Creek BDAs and PALS


Castle Creek

South Fork Clearwater River

Aug. 02, 2021



Project Goals and Objectives

The purpose of this project is to raise the water table, access the floodplain, and transport fine sediment. The wood structures were placed so as to mimic natural structures (beaver dams) designed to function during moderate flows to impound water, scour pools, redistribute sediment, and improve channel complexity for spawning and rearing habitat along roughly a quarter mile stretch of Castle Creek. The intent is to mimic the natural conditions created by beaver dam construction and their effects on stream geomorphology and to encourage beaver occupation of the structures. The stream previously had flood mitigation work done to its channel in 1994, which has effectively straightened the channel. Adding BDAs and PALS will encourage the stream to have a more natural curvature and prevent the channel from incising, as well as create pools for fish habitat. This stream was identified as high habitat potential, a historic stronghold, and steelhead present with migration and winter rearing habitat in the 1999 South Fork Clearwater Landscape Assessment. The lower section of Castle Creek is also Endangered Species Act designated steelhead critical habitat. All work will be done by hand using a hydraulic post driver, chainsaw, and hand tools with access to the project sites along the existing USFS work center access road. Floodplain inundation may be more frequent in the areas of the BDA and PALS installations. All PALS will aim to divert the stream to the far bank, allowing the stream to access its floodplain once again. Beneficial effects for wetland vegetation, stream substrate sorting, and beaver habitat enhancement are expected.

Structure Construction Elements

Structures were primarily BDAs with a few PALS structures included with the intention to redirect the stream flow to the lowered floodplain. The structures utilized locally collected down fir and pine trees as posts installed using a hydraulic post driver in two post rows with local alder and dogwood as fill material to create in-stream structures that will recruit additional vegetation and organic debris. All structures are comprised of locally gathered un-treated plant materials.

Project Photos
Photo of Castle Creek BDAs and PALS

Cover Photo

Project Location