Vegetation and sediment were removed from the Nooksack River channel to encourage more flow into an existing small side channel that runs parallel to the Twin View Levee along the left (west) bank of the river directly upstream of the Highway 544 bridge in Everson. This pilot project is a short-term action designed so that permitting could be completed and the project installed before the 2022-23 winter season. The pilot project is designed to encourage natural river processes that could increase river capacity in the Everson Flow Split area. Flow and habitat changes in the project area will be monitored and evaluated after a full wet season. Results will inform future mid- and long-term actions.
This pilot project was identified by the Everson Flow Split Reach Team in the spring of 2022 as a short-term, multi-benefit action to reduce flood impacts in the Nooksack River and the flood overflow corridor from Everson to the Fraser River. The project was identified as an action that could be permitted and completed before the 2022-2023 winter season. The Whatcom County Flood Control Zone District (FCZD) completed this project in consultation with the cities of Everson, Nooksack, and Sumas, the Nooksack Indian Tribe, and Lummi Nation.
The Nooksack River overtops its east (right) bank at Everson in large flood events, and that flow moves north through the cities of Everson, Nooksack, and Sumas as well as adjacent agricultural areas, posing significant risks to people, infrastructure, and land uses. An interdisciplinary planning and design charrette focused on this river “flow split” was held in April 2022 as an initial step to identify both short-term and long-term multi-benefit solutions for reducing flood impacts in the overflow corridor.
This project is a short-term action identified through this planning effort to encourage a greater amount of flow into a small side channel that runs parallel to the Twin View Levee along the left (west) bank of the Nooksack River immediately upstream of the Everson Road (State Route 544) Bridge. This side channel was active a decade ago, but now only has flow conveyance during high-flow events. Preliminary analysis suggests that increased flow down this side channel could lead to a modest increase in local river flow conveyance and an associated reduction in the volume and rate of flow that overtops the river’s right bank during large flood events.