California’s Largest Floodplain Restoration Project
Our Dos Rios project is the largest public-private floodplain restoration project in California. In July 2018, the New York Times showcased our Dos Rios Ranch project as a leading example of green infrastructure that lowers flood risk and benefits endangered animals.
Ten years and $40 million from eleven different funding sources converge in one important location at the confluence of the Tuolumne and San Joaquin Rivers. Here, River Partners is demonstrating the exceptional value of recovered floodplains in an internationally-recognized area in the Pacific Flyway, a global migration corridor for birds. We are restoring habitat for threatened and endangered wildlife that traverse the planet from Argentina to the Artic. Habitat conservation here has led to the de-listing of one endangered migrating species: the Aleutian Cackling Goose.
Based on years of learning by doing, River Partners is designing a habitat preserve that goes far beyond single-species or single-suite focus. We are actively balancing the habitat needs of the entire ecosystem, and using real-life lessons to guide our actions. The site provides large-scale provision for riparian brush rabbit, riparian woodrat, Swainson’s hawk, Central Valley Chinook salmon, steelhead trout, least Bell’s vireo, yellow warbler, sandhill crane, and the entire suite of neo-tropical migratory songbirds.
Our pilot studies at Dos Rios document the growth benefits of floodplains for foraging for juvenile salmon, and we are in the process of building agency consensus around the design of a water control structure that will increase residence time for floodwaters to benefit foraging juveniles. We have installed wildlife monitoring cameras that have identified new occurrences of threatened and endangered species (riparian brush rabbit) which have guided the placement and configuration of habitat features for rabbits. With partner bird monitoring organizations, we have documented that the diversity of the breeding bird populations in restored habitats at Dos Rios is similar to that of mature forests after just two growing seasons.
Half of Dos Rios Ranch was disconnected from the river by berms created by prior farmers, which were strategically notched and removed in 2018. Two endangered mammals, five endangered birds, and three endangered fish species can now access 1,000 acres of seasonally flooded lands. The remaining acreage is disconnected from the river by a federal levee. A plan has been developed to breach this levee, but many administrative hurdles must still be overcome before we move the dirt.
Why not just set back the levee? It turns out that there may be an even greater flood benefit leaving it in place. With a controlled breach, the lands behind the levee may be able to provide 10,000 acre-feet of transient floodwater storage which could reduce flood stage as far north as Stockton. At Dos Rios Ranch we are partnering with teams of experts to explore groundwater science and the capacity of restored floodplains to bolster freshwater conservation.