The mile long viaduct, which extends north from where the bypass crosses over East Valley Street, is an essential part of the Willits Bypass Project. The viaduct – a bridge over normally dry land – bridges over the 100-year floodplain. A surface level highway through the floodplain would have impacted many acres of wetlands and affected the drainage of the floodplain. The wetlands under the viaduct will only be temporarily impacted during construction. And because the viaduct is located just to the east of a natural row of trees, it will be shielded from the view of most Willits residents.
This viaduct is just one part of the final bypass route chosen from over 30 potential alternatives, and approved by: California Department of Fish and Wildlife; North Coast Regional Water Quality Control Board; U. S. Environmental Protection Agency; U. S. Army Corps of Engineers; National Marine Fisheries Service; and the U. S. Fish and Wildlife Service.