Reach 4B, Eastside Bypass, and Mariposa Bypass Channel and Structural Improvements Project Draft Technical Summary Report SAN JOAQUIN RIVER RESTORATION PROGRAM ---------------- Draft November 2018 --- Mission Statements The Department of the Interior protects and manages the Nation's natural resources and cultural heritage; provides scientific and other information about those resources; and honors its trust responsibilities or special commitments to American Indians, Alaska Natives, and affiliated island communities. The mission of the Bureau of Reclamation is to manage, develop, and protect water and related resources in an environmentally and economically sound manner in the interest of the American public. U.S. Department of the Interior Bureau of Reclamation November 2018 Mission Statements Reach 4B/ESB Project Technical Summary Report Contents Chapter 1 Introduction ................................................................................................................................. 1-1 1.1 Reach 4B, Eastside Bypass, and Mariposa Bypass...................................................................................... 1-1 1.2 Settlement Requirements .............................................................................................................................. 1-2 1.3 Project Area..................................................................................................................................................... 1-3 1.4 Purpose of this Report.................................................................................................................................... 1-4 Chapter 2 Alternatives.................................................................................................................................. 2-1 2.1 No Action Alternative ...................................................................................................................................... 2-1 2.2 Action Alternatives Summary ......................................................................................................................... 2-2 2.3 Alternative 1 – Main Channel Restoration.................................................................................................... 2-3 2.3.1 Flow Routing........................................................................................................................................... 2-3 2.3.2 Construction Actions.............................................................................................................................. 2-3 2.3.3 Operations .............................................................................................................................................. 2-6 2.4 Alternative 2 – Bypass Restoration ............................................................................................................... 2-6 2.4.1 Flow Routing........................................................................................................................................... 2-6 2.4.2 Construction Actions.............................................................................................................................. 2-7 2.4.3 Operations ............................................................................................................................................ 2-12 2.5 Alternative 3 – Bypass All Pulse Flows ........................................................................................................2-13 2.5.1 Flow Routing......................................................................................................................................... 2-13 2.5.2 Construction Actions............................................................................................................................2-13 2.5.3 Operations ............................................................................................................................................ 2-16 Chapter 3 Hydrology and Flood Operations.......................................................................................... 3-1 3.1 Setting ............................................................................................................................................................. 3-1 3.1.1 Hydrology ................................................................................................................................................ 3-1 3.1.2 Flood Management Structures.............................................................................................................. 3-2 3.1.3 Levees..................................................................................................................................................... 3-3 3.1.4 Subsidence............................................................................................................................................. 3-3 3.1.5 Flood Management Operations and Conditions .................................................................................. 3-4 3.2 Alternative Comparison .................................................................................................................................. 3-4 3.2.1 Flood Flows............................................................................................................................................. 3-4 3.2.2 Straying Pathways.................................................................................................................................. 3-7 3.2.3 Subsidence............................................................................................................................................. 3-7 Chapter4 River Geomorphology and Sedimentation ....................................................................... 4-1 4.1 Setting ............................................................................................................................................................. 4-1 4.1.1 River Geomorphology and Sediment Transport ................................................................................... 4-1 4.1.2 Subsidence............................................................................................................................................. 4-4 4.2 Alternative Comparison .................................................................................................................................. 4-6 4.2.1 Sediment Transport ............................................................................................................................... 4-6 ----------------- Contents i Reach 4B/ESB Project Technical Summary Report --- Chapter 5 Vegetation and Soils .................................................................................................................. 5-1 5.1 Setting ............................................................................................................................................................. 5-1 5.1.1 Regional Setting..................................................................................................................................... 5-1 5.1.2 Reach 4B/ESB Project Habitat.............................................................................................................. 5-1 5.1.3 Invasive Plants ....................................................................................................................................... 5-5 5.1.4 Soils ........................................................................................................................................................ 5-6 5.2 Alternative Comparison .................................................................................................................................. 5-9 5.2.1 Direct Effects to Vegetation................................................................................................................... 5-9 5.2.2 Revegetation .......................................................................................................................................... 5-9 5.2.3 Invasive Species................................................................................................................................... 5-10 Chapter 6 Groundwater................................................................................................................................ 6-1 6.1 Setting ............................................................................................................................................................. 6-1 6.1.1 Regional Groundwater Conditions ........................................................................................................ 6-1 6.1.2 Local Hydrogeology ................................................................................................................................ 6-2 6.1.3 Local Groundwater Levels ..................................................................................................................... 6-3 6.1.4 Local Land Subsidence.......................................................................................................................... 6-4 6.1.5 Local Groundwater Quality .................................................................................................................... 6-4 6.1.6 Seepage Management Project along San Joaquin River..................................................................... 6-4 6.2 Alternative Comparison