Oroville Wildlife Area Flood Stage Reduction Project

cbec was sub contracted by PBI to provide a geomorphic assessment of the Feather River in vicinity of the South Unit Oroville Wildlife Area to support the Flood Stage Reduction Project (FSR).

The OWA FSR project consisted of weir improvements and ecosystem restoration to increase connectivity of the Feather River to its historic floodplain and reduce stages within the main channel. cbec provided reconnaissance level geomorphic assessments which was important to better understand the potential impacts of the project to sediment supply and subsequently to water quality associated with existing mine tailings and sediment deposits within the OWA. cbec assessed 7 miles of Feather River including identifying historical influences, current hydrology and geomorphology. cbec conducted historical bank line analysis based on existing datasets and aerial photos, cross section change analysis, and field-based geomorphic reach characterizations.

cbec assessment showed that the FSR Project should have minimal affect on the hydraulics, geomorphology, and water quality of the Feather River relative to present day. Reductions in stream power on the Feather River between the inlet and outlet weirs may help to slow river armoring while not further diminishing the supply of sediment from the dredge tailings. If a future phase of the FSR Project includes expansion beyond the current 400 ft weir alternative, then cbec recommends the use of sediment transport models to more definitively quantify the potential for geomorphic impacts to the Feather River and fine sediments within the OWA D-Unit floodplain to be mobilized and transported.

Waterbody / Watershed

Feather River