Fast Facts
- Through the Bipartisan Budget Act, USACE received $1.8 billion full upfront funding to modernize Sacramento’s aging flood infrastructure at locations along the American River, Sacramento River and the Sacramento Weir.
- Supplemental funding provided in 2018 allocated more than $200 million to complete the Folsom Dam Raise project, which will provide additional surcharge storage space in Folsom Dam during high water events.
- Improvements to the 42 miles of levee surrounding the Natomas Basin have been consistently funded since USACE began construction on the $1.3 billion project in 2017.
Background Info
Greater Sacramento, California, is considered to be the most at-risk region in America for catastrophic flooding, relying on an aging system of levees, weirs and bypasses and Folsom Dam to reduce its flood risk. But that system, just like a chain, is only as strong as its weakest link. Together, the U.S. Army Corps of Engineers, California’s Central Valley Flood Protection Board, California Department of Water Resources, and the Sacramento Area Flood Control Agency have made tremendous progress in reducing the flood risk, but more work remains. Through the Bipartisan Budget Act, the Corps has received full upfront funding to modernize Sacramento's aging flood infrastructure. This allows us to more efficiently implement nearly $1.8 billion in upgrades to Sacramento's flood risk management system. The authorized work includes up to 13 miles of seepage cutoff walls, 21 miles of bank protection, five miles of levee stabilization, five miles of levee raises and widening the Sacramento Weir and bypass.
Sacramento Weir Widening
The Sacramento Weir Widening Project is located immediately north of the City of West Sacramento in Yolo County, California, and along the western bank of the Sacramento River. The project location is approximately three miles upstream from the confluence with the American River and located north of the existing Sacramento Weir (constructed in 1916).
The project is designed to increase the volume of flood waters that can be transferred from the Sacramento River to the Yolo Bypass to reduce river stages along the Sacramento River and local tributaries and to significantly reduces flood risk to the American River levee systems. The project also provides fish passage from Tule Canal to the Sacramento River utilizing a channel in the bypass and a fish passage structure to alleviate stranding, mortality and migration delays of Endangered Species Act-listed species. The existing weir standard project flood is 112,000 cubic feet of water per second. The widened Sacramento Weir expands the design flood control discharge to a total of 177,000 CFS between the existing and widened weirs.
American River Common Features (ARCF) 2016
The City of Sacramento is at significant risk of flooding. Its watershed is comprised of three principal streams: North, Middle and South Forks of the American River, that flow westward into Folsom Lake, through Sacramento and into the Sacramento River. To reduce the very high flood risk to approximately 530,000 people and 125,000 structures within the Sacramento Metropolitan Area this project is authorized to construct improvements to address seepage/ stability (18 miles), overtopping (5 miles and weir and bypass) and erosion (21 miles).
ARCF Natomas Basin, Sacramento and Sutter Counties
The Natomas Basin in Sacramento and Sutter counties is one of the most at-risk areas in the nation for catastrophic flooding. It is protected from flooding by a continuous 42-mile ring levee system bounded to the north by the Natomas Cross Canal, to the west by the Sacramento River, to the south by American River, and to the east by the Natomas East Main Drainage Canal and the Pleasant Grove Creek Canal (PGCC).
A catastrophic failure of the levee system surrounding the Natomas community could threaten at least 100,000 lives, cause up to $8.5B in property damage and shut down the Sacramento International Airport and two of California’s busiest highways. The U.S. Army Corps of Engineers Sacramento District has divided the Natomas Basin levee system into nine Reaches (A - I) for planning, design, and construction purposes.
Folsom Dam Raise / Joint Federal Project
The purpose of the Folsom Dam Raise Project is to reduce flood risk in the Greater Sacramento area. The overall project includes a raise of the main components of Folsom Dam up to 3.5 feet, along with modifications to the main dam’s tainter gates, construction of automated temperature control shutters at the main dam to benefit American River fisheries, and habitat restoration at two sites along the lower American River. The overall authorization also included construction of the Folsom Dam Bridge (completed in 2009) and the Auxiliary Spillway (completed in 2016).
This work is expected to more effectively use Folsom Lake’s existing surcharge flood storage space as well as increase the temporary water storage space that can be used during flood events.
Following the successful raise of Dike 8 in 2020, construction at Mormon Island Auxiliary Dam (MIAD), Dikes 1-6, and the main dam and left/right wing dams began in 2024.
West Sacramento Levee Improvement Project
The City of West Sacramento has a high probability of flooding due to its location at the confluence of the American and Sacramento Rivers, adjacent to the Yolo Bypass and within the Sacramento River floodplain. Both rivers have large watersheds with potential for very high runoff which has overwhelmed the existing flood management system in the past. The city is essentially surrounded by a system of levees that provide flood risk management for the city. The existing levee system was designed and built before modern construction methods were employed. These factors add to a high probability of flooding.
There are over 30 miles of levee improvements around the north and south basins of West Sacramento. These improvements include slurry walls, slope protection, relief wells, and seepage berms.
Yolo Bypass Comprehensive Study
The Water Resources Development Act of 2020, Section 209, authorizes the U.S. Army Corps of Engineers to conduct a comprehensive study of the Sacramento River in the vicinity of the Yolo Bypass System to identify actions for the comprehensive management of the system for the purposes of flood risk management, ecosystem restoration, water supply, and recreation. Federal funding in the amount of $500,000 to “initiate the feasibility phase” was first appropriated in the Consolidated Appropriations Act of 2023.
The study will recognize that the Yolo Bypass System provides multi-purpose benefits and will consider such benefits as flood risk management, water supply, agricultural, habitat restoration, and recreation. The Non-Federal Sponsors are the State of California, the Central Valley Flood Protection Board (CVFPB) and the Sacramento Area Flood Control Agency (SAFCA). Additionally, the Yolo Bypass and Cache Slough Partnership is a stakeholder.