Army Corps of Engineers repairing Koch Slough Fishway near Silvana

Published Aug. 1, 2020

Efforts to improve fish passage at the Koch Slough in Snohomish County starts today as Seattle District, U.S. Army Corps of Engineers’ officials begin repairing the fishway on the Stillaguamish River near Silvana, Washington.

The $3.1 Million federally-funded construction project will replace and restructure the fishway improving fish passage for migrating Pacific salmon and trout.

All in-water work is scheduled to be complete by Sept. 30, the end of the “fish window” when construction crews can work in the water with the least amount of disruption to fish.  Above-ground work is expected to last through the end of October.

Construction work includes removing the existing rock fishway and repairing the fish ladder with a series of precast concrete fish ladder weirs that will be attached to sheet pile walls and function over a wide range of flows. External baffles will be installed on the north side of the fish ladder walls to enhance passage at high flows.

Throughout the planning process, the Corps coordinated with a number of interested agencies and stakeholders to develop a plan to restructure the Koch Slough Fishway.

Scott Lawrence
206-379-7269 (cell)

Release no. 20-112