American River Parkway Cordova Creek Naturalization

cbec provided restoration and rehabilitation design services on Cordova Creek located just off the American River Parkway in Rancho Cordova, CA. This urban stream rehabilitation project restored ecological function by removing an existing trapezoidal shaped concrete-lined channel that discharged treated groundwater, stormwater runoff and residential irrigation runoff (previously named the Clifton Drain), and replacing it with a natural winding one (renamed Cordova Creek).

In total, 3,300 lineal feet of concrete channel was removed and replaced with 2,900 lineal feet of interpreted natural stream channel, as well as the planting of 17 acres of wetland, riparian and upland vegetation. 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 2016 to early 2017, with Phase II designs currently in progress to restore the last section of channel that directly connects to the Lower American River. This involves the removal of the last remnants of the concrete-lined channel. By 2017, Cordova Creek had a natural stream substrate and banks consistent with historical drainage patterns. Phase I of this project went on to win the ASCE Sacramento Section’s Environmental Engineering Project of the Year in 2017.

cbec 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. Specific tasks included riprap design, bed particle transport analysis, and design 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 an unmanned aerial systems (UAS) technology to monitor plant health and vegetation recruitment. cbec’s overall approach methodology included three equal considerations of habitat quality, aesthetics, and functionality. cbec’s ecological approach created a high-quality habitat consistent with what the physical and biological conditions of the site could support. It focused on both the underbrush and the tree canopy to create habitats that establish successfully, quickly, and with 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 suppress weed competition with native trees and shrubs. cbec’s driving philosophy for restoration 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. Other local-scale actions considered included reconnecting the channel to the floodplain by removing/lowering high floodplain terrace elevations, allowing the channel ‘room to roam’ and to promote connectivity to the floodplain.

In 2017, cbec performed post project multi-spectral aerial surveying to monitor restoration plantings at the site. Find out more about that process here. The video below reveals the flourishing project site in September 2017.