Bessey's North Fork Siuslaw & McLeod Creek Floodplain Restoration

This project addressed each of the major stresses and limiting factors hindering production of coho on the Oregon Coast as identified through extensive watershed assessment and restoration planning at the local, state, and federal levels. Its process based design required regrading specific portions of the floodplain to low flow water surface elevations, to provide a slower velocity environment, enabling the development of complex channel and floodplain habitats. The project created an inset within the existing floodplain where conditions emulate those expected historically, exhibiting an anastomosing channel network fully loaded with LWD, and a diverse assemblage of native vegetation. Instream habitat funds expended were much higher than proposed due to unforseen issues related to permitting for fill disposal sites and utilizing alternative sites in a safe and efficient manner.
PCSRF FFY 2017 funds were expended on project costs incurred during the PCSRF FFY 2017 contract award period. OWEB state funds and Other sources of funds will be used to complete the project. No funds are reported as match to PCSRF funds.

The Bessey NF Siuslaw and McLeod Creek Floodplain Restoration will benefit salmon and steelhead by directly addressing each of the major stresses and habitat related limiting factors for OC Coho identified within the primary local (Siuslaw SAP, SCP 2018), state (Oregons Coastal Coho Assessment, ODFW 2005), and federal (Federal Recovery Plan For Oregon Coast Coho, NOAA 2016) recovery plans. This project will modify an incised and isolated section of floodplain at the confluence of the NF Siuslaw and McLeod Creek (Stage 3-4, as depicted in the Cluer and Thorne Stream Evolution Model) in order to heighten the ecological productivity onsite. Current conditions provide only limited habitat value for native salmon and steelhead. The project will create an inset within the existing terraced floodplain that actually functions like an active floodplain is supposed to naturally, in a portion of watershed that hasn’t had such in several decades. Within the active inset floodplain resulting conditions will emulate those expected historically, complete with a complex anastomosing channel network fully loaded with LWD, and an assemblage of native riparian/wetland vegetation. The floodplain restoration treatments will create vital off-channel habitats, important for juvenile rearing and high water refugia. Wetland conditions within the lowered inset floodplain will drastically increase over time. The floodplain water storage capacity will increase, extending the duration of slow metered releases. These exchanges between the cold oxygenated ground water and the surface waters will keep flows cooler and higher for longer, throughout the limiting summer months, which will improve rearing survivorship. The increase in the cross sectional area and instream complexity will slow flows enough to sort and aggrade the stream bed with a mosaic of valuable spawning substrate types for all salmonid species. The stream bank treatments and native vegetation establishment will reduce chronic non-point source pollution inputs, improve nutrient cycling, and increase shade relief to surface waters; improving water quality overall. Each of the project’s components will complement each other, synergistically amplifying the productive capacity of habitat for native salmonids, including the federally listed OC Coho.