Verdantas provided restoration and rehabilitation design services on Cordova Creek, located immediately south of the lower American River in Rancho Cordova, CA. This award-winning urban stream rehabilitation project restored ecological function by removing an existing trapezoidal-shaped, concrete-lined channel (previously named the Clifton Drain) that discharged treated groundwater, stormwater and residential irrigation runoff to the lower American River. The concrete channel was replaced with a natural meandering course, surrounded by riparian vegetation. In total, 3,300 linear feet of concrete channel were removed and replaced with 2,900 linear feet of interpreted natural stream channel, and 17 acres of wetland, riparian, and upland areas were revegetated. In addition, a public trail with interpretive signage was constructed along the creek, connecting nearby neighborhoods to the extensive Jedidiah Smith Memorial Trail.

Multiple stakeholders were involved with this project, including the Sacramento County Departments of Water Resources and Regional Parks, Water Forum, City of Rancho Cordova, Soil Born Farms, California Native Plant Society, and Sacramento Area Flood Control Agency. This project was made possible through funding from the Wildlife Conservation Board and California Natural Resources Agency. Phase I construction took place from late 2015 to early 2017. By the end of 2017, Cordova Creek had a natural stream substrate and banks, and an alignment consistent with the historical drainage. The project has won two restoration awards, including the American Society of Civil Engineers 2017 Environmental Project of the Year and a Sacramento Environmental Commission 2016 Outstanding Environmental Stewardship award. Phase II is in progress, with construction tentatively planned for 2027, pending grant funding, final design, and permitting.

Verdantas was the prime consultant for this effort. The project involved geomorphic analysis, floodplain restoration, and biotechnical bank stabilization and grade control on a system with highly erosive soils and increased flows due to a hydromodified watershed. Verdantas’ tasks included alternatives development and evaluation, flood modeling, bed particle transport analysis, riprap design, and compliance and quality control services during construction. In addition to traditional ground surveys (both for pre- and post-project conditions), post-construction monitoring was conducted via unmanned aerial systems technology to monitor plant health and vegetation recruitment. 

Verdantas' overall approach included equal considerations of habitat quality, aesthetics, recreational access, and functionality, which created a high-quality habitat consistent with the native physical and biological conditions of the site. It focused on both the underbrush and the tree canopy to create habitats that establish successfully, quickly, and require minimal ongoing maintenance needs. Designs included planting the entire site (not just upland grassland areas) with native herbaceous plants and grasses to establish as much native plant cover as possible and thereby outcompete non-native weeds. Verdantas’ driving philosophy was to restore natural river process to the maximum extent practicable, given constraints imposed by the degree of creek modification, land ownership, local economy, and public amenities and facilities.

Funding acquisition allowed Phase II to commence in 2020. This phase achieved a 65% restoration design of the last 430 linear feet of channel to provide fish passage from the lower American River for juvenile salmonids to access off-channel habitat. This involves replacing the last remnants of the steep, concrete-lined channel with a naturalized rock step-pool channel, enhancing aquatic and terrestrial habitat types to benefit a diversity of species. A wider, more modern bridge will replace the current one, promoting accessibility for various modes of transportation, and improving safety for recreational, educational, and interpretive users. Verdantas developed hydrology on this ungauged creek to support hydraulic modeling, habitat evaluations, and channel design. Verdantas provided channel inundation and hydraulic data for a restoration ecology firm to design wetland, riparian, and upland vegetation zones. The Phase II project included a very collaborative concept vetting and design review process that engaged a diverse stakeholder group.