Hatchet Slough Tidegate Replacement and Fish Passage Project - Phase 1

This grant was intended to be the first step in designs to replace an undersized and failing tide gate and identify upstream habitat restoration priorities for Hatchet Slough. However, the primary landowner has canceled the project. During the application process, the Coquille Watershed Association had many conversations with the landowner to explain the process and future commitment (i.e. long-term agreements and ecological uplift) should conservation funding be used to replace the tide gate. The landowner, who showed an interest in promoting fish habitat, understood and agreed to the process. In spring 2021, the landowner began pulling back the commitment to ecological enhancement. CoqWA participated in multiple meetings with the landowner to present various possible scenarios for ecological uplift, but making it clear that there would be a need for habitat enhancement in addition to the tide gate being replaced. An additional sticking point was the mandatory 10-year landowner agreement that would be required upon implementation of a new tide gate. It was explained that no management decisions would be made without landowner approval, but a long-term agreement for an investment of this magnitude would be required upon implementation. Ultimately, the landowner decided these were not terms they could agree to and the project was terminated.

This technical assistance grant will benefit salmon, steelhead and other native fish by restoring fish access to critical slow-water refugia, rearing habitat and spawning habitat within the Hatchet Slough watershed. The failing tidegate, and to a lesser extent the undersized county culvert, currently limit fish access to Hatchet Slough and other unnamed tributaries. In total this project area contains over 3 miles of fish habitat, with much of that habitat suitable for coho. By providing funds to initiate the development of project designs, this investment will ultimately result in a fish passage restoration project that will provide fish access to a high priority sub-watershed in the Coquille Estuary. In addition to using upstream reaches for spawning habitat, juvenile coho and other anadromous fish use tidal wetland habitats for feeding, rearing and as a source of slow water refugia during high winter flows. Studies have shown smolt growth rates are often 1.5-2.0 times greater for off-channel and tidal wetland habitats compared to stream locations (Nickelson 2012, ODFW, unpublished 2014). The initial designs created by this project will facilitate the replacement of the Hatchet Slough tidegate, improving fish passage to 70 acres of tidally influenced habitat. Nickelson (2007) estimated that these types of habitats historically were capable of rearing sufficient numbers of coho juveniles to produce 11-17 returning coho adults for every acre of high functioning floodplain wetland. Accordingly, the tidal wetland habitat within Hatchet Slough Valley will have the capacity to annually produce 770 to 1,190 returning adult coho.