Radiant Creek is located within the upper Clearwater River, one of the priority watersheds identified by Alberta Environment and Parks (AEP) for native trout recovery. In the recent past, Radiant Creek has flooded out of its natural channel downstream of the Forestry Trunk Road. It is likely the road and culvert or bridge at the time exacerbated the effects of flooding resulting in a flow constriction, causing increased stream velocity – similar to the effect you get when you pinch a garden hose. Following the flooding, increased grazing and trampling pressure on the riparian area and stream bed by cattle and wild horses have not allowed this degraded stream reach to recover resulting in it becoming shallower and wider than upstream and downstream reaches. To address this issue, Trout Unlimited Canada (TUC) has implemented a “low tech processed-based restoration (LTPBR)” pilot project. LTPBR is a stream restoration concept that uses simple, low-cost structural additions in structurally starved riverscapes. The specific technique used at Radiant Creek is known as Post-Assisted Log Structures (PALS). PALS are simulated log jams made by piling logs and branches in the river and pinning them in place with untreated wooden posts. The PALS are strategically placed in order to encourage the stream to meander, create undercut banks, scour deeper sections, and gather fine materials into gravel and sand bars – essentially to mimic and promote the natural process of wood accumulation. The goal is to create complex habitat and stream function using all-natural materials and the power of the flowing water. This process takes time, and the PALS are built to interact with high water events and spring freshets as well as the normal seasonal flows of the stream. Eventually, the untreated posts will rot, and the PALS will transition from man-made structures to lose woody debris in the stream. Prior to completing PALS installation, six transects were established within the project area. At each transect, the crew measured wetted width, wetted depth, bankfull width, and bankfull depth at the cross section. The locations and depth of pools and riffles were also measured and photographed. These data will help to document how the creek responds to the treatment applied. TUC and our partners will continue to monitor the success of the project and make adjustments as needed to ensure positive outcomes, including improved riparian health and function, improved water storage and retention, and year-round habitat for Bull Trout.
On July 13-16, 2021, TUC constructed ten PALS in the project area, consisting of two mid-channel PALS, and eight bank-attached PALS. For materials, the large woody debris was sourced from a local forestry company. A contractor was hired to deliver the debris (made up of conifer trees) and distribute the debris in piles along the project area in fall 2020. Sharpened, untreated wooden posts were also purchased from a local supplier. These posts were 6 feet long, and 3 inches in diameter. To construct the PALS, woody debris was put into place by hand by a crew of 6-8 people. The debris was arranged with the direction of scour and aggradation in mind. Then, the untreated posts were driven into the streambed using a gas powered post pounder to pin the debris piles in place. To fill in the larger holes, additional pieces of smaller debris were used. Finally, approximately 500 willow stakes were planted throughout the project area.