Chapter 4 Hydrology, Hydraulics, and Flood Control
4 Hydrology, Hydraulics, and Flood Control 4 Hydrology, Hydraulics, and Flood Control This chapter addresses the water resources within the Yolo Bypass Salmonid Habitat Restoration and Fish Passage Project (Project) area and describes potential effects of Project implementation on those resources. Water resources include hydrology, hydraulics, and flood control. The analysis provided in this chapter includes a description of existing environmental conditions; methods used to assess environmental effects; potential direct, indirect, and cumulative impacts of Project implementation; and mitigation measures recommended to avoid or minimize adverse effects under National Environmental Policy Act (NEPA) and significant impacts under California Environmental Quality Act (CEQA). Federal, State of California (State), and local regulations that pertain to flood control, hydraulics, and hydrology are summarized. 4.1 Environmental Setting/Affected Environment This section presents the environmental setting for hydrology, hydraulics, and flood control in the Project area. 4.1.1 Hydrology and Hydraulics The Project area for hydrology and hydraulics consists of the Sacramento River from Shasta Dam to Rio Vista, the Yolo Bypass, and the Sacramento-San Joaquin Delta (Delta) in the vicinity of Cache Slough (Figure 4-1). These areas are described below. 4.1.1.1 Sacramento River The Sacramento River has been divided into two reaches, one above the Fremont Weir, and one below the Fremont Weir. These two reaches are discussed separately because they are affected by the proposed project differently. 4.1.1.1.1 Sacramento River from Shasta Dam to Fremont Weir Flows in the 65-mile Shasta Dam to Red Bluff (River Mile [RM] 244) reach of the Sacramento River are regulated by Shasta Dam and are reregulated downstream at Keswick Dam (RM 302), as shown in Figure 4-1.
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