Lower Clear Creek Riparian Enhancement – Reaches 57 & 58

The Lower Clear Creek Riparian Enhancement – Reaches 57 & 58 project enhanced 27 acres of riparian habitat along 1.3 miles of Lower Clear Creek on the upper reaches of private land. Native trees and shrubs were planted along the streambank and point bars, capitalizing on the past two seasons of successful knotweed treatments, and providing future sources of shade and instream large wood. Idaho SWCD scouted for and treated knotweed across the entire riparian buffer to assist with the natural recovery of desirable plant species and minimize the spread of knotweed downstream. A weed competitive native grass seed and forb mix was applied to areas devoid of vegetation to help prevent knotweed reestablishment. Onsite monitoring efforts showed an 81% survival rate on plantings one year after plantings were completed. The native seed showed a 90% survival rate.



Limiting factors in Reaches 57 & 58 on Clear Creek include a lack of pools, large woody debris, and canopy cover. Despite these limitations, the reaches were also identified as having the highest steelhead and juvenile chinook abundance in the watershed, the only population of juvenile Coho, and the greatest abundance of spawning gravel. Thus, the benefits of addressing the identified limiting factors on the private land reaches are likely to benefit all three salmonid species by improving juvenile survival and spawning success.

The project will revegetate key areas along Lower Clear Creek (Reaches 57 &58) where knotweed has recently been successfully treated, and the establishment of woody vegetation will provide shade and future sources of large wood recruitment for in-channel habitat. Once woody vegetation is established, large wood instream will create pools for adult salmonid holding and juvenile rearing habitat, provide refuge habitat for juvenile and adult fish at a wide range of stream flows, and provide food sources and habitat for aquatic insects along Lower Clear Creek. In addition to increasing the habitat complexity for salmonids, the desired future condition contains a mosaic of mature and young age class conifers and riparian shrubs that provide channel roughness and promote floodwater retention. The strategy we develop for successfully treating knotweed will inform future projects where releasing competitive pressure on native streamside vegetation will benefit native salmonid habitat.