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Oroville Wildlife Area Flood Stage Reduction Project

  • By Helen Swagerty, Senior Restoration Ecologist

Above: Invasive water primrose in existing channels and ponds.

The Oroville Wildlife Area Flood Stage Reduction (OWA FSR) Project, sponsored by Sutter Butte Flood Control Agency (SBFCA), is part of SBFCA’s goal of improving flood protection along the Feather River corridor. The OWA FSR project consists of weir improvements and ecosystem restoration on Unit D of the Oroville Wildlife Area, near the Thermalito Afterbay Outlet. The objective is to improve the connectivity of the Feather spotRiver to its historic floodway, protect flood relief structures and reduce peak stages within the main channel.

SBFCA retained an engineering firm, Peterson Brustad, Inc., and River Partners to develop this project. Our role is to design the multi-benefit components, which include ecosystem restoration and recreation amenities, and to prepare a restoration master plan that describes how these elements could be implemented through phases.

The project lies across from the Thermalito Afterbay Outlet, a popular fishing spot.

Currently, Unit D of the Oroville Wildlife Area is a highly disturbed floodplain that includes extensive, isolated ridges and piles of rock left by gold dredging and drainage canals created during the time the site served as a borrow area for the construction of Oroville Dam. One of the habitat restoration design objectives is to improve habitat for native fish species including Chinook salmon (Oncorhynchus tshawytscha) and steelhead trout (Onchorhynchus mykiss). Because there are design constraints due to temperature and flow requirements in the Feather River associated with Oroville Dam FERC (Federal Energy Regulatory Commission) relicensing efforts, we have taken a collaborative and interdisciplinary approach. We have been working with the California Department of Water Resources (DWR), the California Department of Fish and Wildlife (CDFW), and researchers from the University of California Davis on project alternatives that aim to balance these requirements with the desire to provide appropriate habitat for aquatic and terrestrial species, offer recreational amenities, and improve flood protection. We hope that designs to enhance drainage channels by removing invasive water primrose (Ludwigia hexapetala) and improvements to the existing upstream and downstream weir structures aid in decreasing potential fish entrapment areas and increasing floodplain connectivity to provide off-channel refugia for native fish.

The above article originally appeared in the Winter 2015 issue of the River Partners Journal.