Using historical photographs, anecdotal evidence and local knowledge, TU worked with project designers Doug Ray of Carex Consulting and Joseph Shehan from Oregon Dept of Fish and Wildlife to re-excavate a 14 plus acre historic off-channel wetland on the Necanicum River. The channel had been filled and converted to ag land. Habitats such as this are critical foraging and rearing areas for juvenile salmonids like coho and cutthroat trout. By adding large wood and native vegetation the health and diversity of the area has rebounded significantly.
Depths of excavation were targeted to allow groundwater flows underneath project site to re-water channel, while connection to mainstem Necanicum River was precisely engineered to allow in-flow during high water and out-flow during receding flows, as well as safe passage for juvenile fish. Hundreds of large wood pieces were placed in the restored channel for habitat complexity, cover and scour flows and a carefully developed native wetland and Sitka spruce swamp native plant revegetation program was implemented over three years.
In response, groundwater flows began watering new channel immediately, and mainstem connection was made with main river channel at first high water event. Coho juveniles were observed in project reach almost immediately after. Nocturnal coho spotlight surveys have consistently shown very high juvenile usage. Temperatures (due to groundwater influence) were consistently 4-5 degrees C cooler in summer and warmer in winter, ideal for juvenile salmonids. Connection with mainstem Necanicum River has remained fully functional through several seasons through 100-year flood events and dry summer months, allaying any fears of juvenile fish stranding. Native plant program has been hugely successful, and has thrived with the help of local TU chapter (Tualatin Valley) stewardship. Landowner, Mrs Ernestine Neitzel and her family, have received accolades from science community, state agencies and U.S. Congress since the completion of the project.