Abbott Lake Restoration Moving Ahead
(Above) Initial planting at Abbott Lake.
In July of 2014, the Central Valley Flood Protection Board issued an encroachment permit to the California Department of Fish and Wildlife (CDFW) enabling River Partners to begin work on the Abbott Lake Unit of the Feather River Wildlife Area. The effort to obtain the permit took four and one-half years of negotiations that, to a great extent, revolved around the question of the effect that restored vegetation in floodways has on floodwater conveyance and flood safety.
Located approximately seven miles south of Yuba City in the Sacramento Valley, the 439-acre Abbott Lake site has been fallow for 25 years. Through a grant from the California Wildlife Conservation Board, River Partners will actively restore 150 acres and help enhance the remnant habitat by controlling invasive plants. Since this unit belongs to the CDFW, the project will also benefit public recreation and access to the Feather River once restoration is completed.
The notion that floodway vegetation is detrimental to flood safety is familiar to the planners and scientists at River Partners and is taken very seriously by them. The long-standing perception has been that floodway vegetation slows down floodwater, raising water levels and potentially jeopardizing levees, bridges, and other infrastructure. However, River Partners believes that native riparian vegetation can be designed to have minimal impact on floodwater conveyance and flood safety. River Partners planting designs include hydraulic modeling that enables River Partners to target where native vegetation can be placed on floodplains to achieve desired outcomes.
For the Abbott Lake restoration project, River Partners hired the engineering firm MBK to conduct the hydraulic analysis of the proposed planting design. Senior Restoration Biologist Helen Swagerty, who is supervising the project, explained that “thanks to MBK’s multiple evaluations and feedback, we’ve carefully adjusted the restoration design—including types of plants, their locations, and densities—so that there specifically won’t be a ‘clogging’ effect if there is a flood. MBK’s modeling of the project’s impact in a flood event has shown that restoration will not burden the flood protection system, and could potentially reduce water velocity adjacent to the levee.”
More than 90% of the historic riparian habitat in California’s Great Central Valley has been lost, and most of the remaining 5 - 10% is in highly degraded condition. The riparian habitat that remains along the Feather River provides critical habitat for numerous wildlife species, including many waterfowl, neotropical migratory songbirds, and special-status species such as Swainson’s hawk and the valley elderberry longhorn beetle. The Abbott Lake project will create additional high-quality riparian habitat, linking fragmented patches of remnant habitat and improving conditions for many wildlife species along the Feather River corridor.
The above article originally appeared in the Winter 2015 issue of the River Partners Journal.