Big Meadow Creek County Culvert Replacement

The goal of this project was to improve access to spawning and rearing habitat for ESA-listed steelhead in Big Meadow Creek. Specifically, contract 024-13-CW provided funds to complete final design and the purchase of three culverts for replacing existing undersized structures that were limiting steelhead passage in Big Meadow Creek. All three culverts and roadways are owned by Northern Latah County Highway District (NLCHD) and NLCHD will retain ownership and maintenance of the new culverts. Replacement of these three culverts compliments the Big Meadow Creek Highway 8 baffle project finished August 2018 at the mouth of Big Meadow Creek (014 16 CW). Beginning in the spring of 2019, much of Big Meadow Creek should be accessible to spawning wild steelhead. This will be the first time that steelhead will have access to the Big Meadow Creek upstream of Hwy 8 since 1977 when the Hwy 8 culvert was installed.

All three culverts were designed to pass upstream-migrating adult steelhead during at least a 25-year flow event. They are also sized to pass flows without overtopping for at least a 100-year event. Design flows were based on regional regression curves from USGS StreamStats, as there is no stream gauge data available for Big Meadow Creek. Passage through the culverts was modeled using USFS FishXing software.

The most downstream culvert (worksite 1) opens 1.0 mile of stream for fish, the middle culvert (worksite 2) opens 0.67 mile of stream for fish, and the most upstream culvert (worksite 3) opens 5.04 miles of stream for fish.

This project, coupled with the culvert passage improvement under Idaho Highway 8, will benefit ESA-listed steelhead through enhanced access to 8.25 miles of spawning and rearing habitat in the Big Meadow Creek watershed. Passage under the Highway 8 culvert will be improved under a separate project scheduled for construction in 2017 or 2018. These fish are part of the Clearwater River lower mainstem population of the Clearwater Major Population Group of the Snake River steelhead Distinct Population Segment.