Status

Completed in fall 2018 with planting in spring 2019

Project Benefits

Reduce flooding potential and improve safety on State Route 542
Reduce the potential for future flood damages to nearby residences and businesses
Improve fish passage for coho salmon, steelhead, and trout
Reduce long-term impacts to the aquatic environment
Provide more predictable maintenance expenses

Background

In 1922, Whatcom County was deeded a drainage right-of-way for the westerly 3,000 feet of High Creek to address flooding damage to adjacent agricultural land and regular closures of the county road servicing the Kendall area. This section of the creek was then placed in a dredged linear channel. The county retained the drainage right-of-way when the road was deeded over to the state to become State Route 542.

Over time, sediment has accumulated in this section of low gradient stream channel, causing the streambed to become higher than the adjacent ground. The elevated streambed increases the risk of flooding. During a 1990 flood event, High Creek overtopped its bank, and flooding damaged nearby homes and businesses. This section of stream channel is also a fish passage barrier to migrating salmon and steelhead where it is shallow and spreads out in an adjoining pasture before entering Kendall Creek. The county evaluated alternatives and developed a sediment management plan as part of an agreement with impacted landowners. This project implements that management plan.

Project Description

This project consisted of the following key pieces. First, sediment was removed from the channel to lower the streambed. Second, the berms lining the channel were shaped to provide a consistent level of flood protection along the full length of the project area. Third, two sediment traps were installed to capture the annual flow of sediment into the project area. These traps will be easily maintained and allow for removal of excess sediment that would otherwise raise the channel bed and reduce flood conveyance. Fourth, a connection of High Creek to Kendall Creek was re-established and habitat structures were installed to provide fish passage and improve instream habitat. Finally, all disturbed areas were planted with native trees and shrubs to protect water quality and improve habitat over the long term.

Engineering Design

Watershed Science and Engineering (WSE) prepared the Sediment Management Plan (see below), performed the hydraulic modeling, and oversaw the engineering design. Pacific Survey and Engineering (PSE) did the engineering design. Whatcom Conservation District developed a detailed planting plan.