In 2006, federal, state and local flood risk management officials determined that many portions of the levees surrounding the Natomas Basin did not meet current federal and state design standards for levee height, seepage and stability and long-term operations and maintenance. The determination led to the conclusion that the basin had less than a 100-year level of flood protection. This means there is a greater than one-in-100 chance in any given year that flooding could occur.

It was determined that additional landside slope improvements were necessary to meet current engineering standards for slope stability and address seepage that may still occur with cutoff walls present. The proposed landside levee improvements include widening the levee to ensure a minimum two horizontal to one vertical (2H:1V) landside slope using cohesive engineered soil materials. Because the cohesive soil material transmits seepage water much slower than does the existing sandy material in the levee, an internal drainage layer is placed between the existing levee and the new levee fill in order to provide for a stable landside levee slope. The work will also conform with the Vegetation Variance authorized in the 2010 Post-Authorization Change Report that stated vegetation located on the landside of the Natomas levee slopes and in operation and maintenance areas would need to be removed to meet access and slope stability requirements. Following removal of this vegetation, any root balls and individual roots greater than 1.5 inches in diameter need to be removed from the levee. This process results in significant excavation of the landside levee slope.

A number of environmental documents have been released over the past decade related to the project in compliance with the California Environmental Quality Act (CEQA) and National Environmental Policy Act (NEPA). Numerous public meetings have been held receive public input and comment on the proposed project. While environmental documentation identifies broad geographical areas, flood risk reduction alternatives, and generally identifies properties that may be impacted by the proposed project, it is important to note that it is not possible to know the final impacts and real estate needs of the project until the 100% design is complete. USACE completed its 65% design plan for Project Reach A levee construction in fall 2019, at which time SAFCA contacted property owners along the entire Reach A project area where a real estate acquisition may be necessary.

Other communication efforts you may have seen:

In December 2018, USACE mailed an information pamphlet to all residents in the 95833 ZIP code informing them of work beginning in the Natomas Basin. At that time, the timeframe as to when work would occur between San Juan Road and Gateway Oaks Drive (referred to as Project Reach A) was not yet determined.

In December 2019, USACE sent a direct mail piece to all properties in the project area indicating that construction between Gateway Oaks Drive and Interstate 80 could begin as early as 2023.

USACE also participated at two public meetings to share information about the project, which were held on November 20, 2019 at Swallows Nest and February 6, 2020 at Two Rivers Elementary School (River Oaks Community Association meeting).

USACE hosted a public webinar on November 16, 2020 to provide additional updates and receive questions from residents and other stakeholders.

Upon initiation of construction, USACE will begin a monthly construction update to provide information on the status of work, road closures, and other pertinent information.

A number of alternative project designs were considered and analyzed through the development of multiple project studies and environmental documents.

The materials used during the construction of the existing levees in the late 1800’s and early 1900's consisted of sandy soils that were dredged from the riverbed. During high river elevations, this type of material has been found to be conducive to excessive seepage that can lead to levee failure. In order to address this deficiency with the least amount of impact, USACE is planning to construct a combination of adjacent levees, deep cutoff walls, stability berms, seepage berms and slope stability improvements at various locations along the Natomas Basin levees.

The construction of an adjacent levee and cutoff wall, where feasible, was found to have the least amount of impact to the existing community and environment while providing flood risk reduction to the region. This work will involve widening the existing levee using engineered fill material, which is compacted on the landside slope of the levee and acts as a barrier to significantly reduce seepage and increase slope stability. The adjacent levee will include either a seepage berm and/or deep cutoff wall depending on the underseepage concerns along the levee. 

Other alternatives that were analyzed include removing the entire existing levee and rebuilding it from the ground up with competent material or constructing wide seepage berms at the toe of the levee along the entire Reach A project area. These alternatives would require much more adverse environmental impacts including additional real estate acquisition, removal of more vegetation than what is currently necessary, and were also shown to be cost-prohibitive.

Project level analysis of levee improvements, alternatives and their potential impacts were included in the 2010 FINAL Environmental Impact Statement/Environmental Impact Report on the American River Watershed Common Features Project/Natomas Post-Authorization Change Report/Natomas Levee Improvement Program, Phase 4b Landside Improvements Project document and subsequent Addendums. The entire document and addenda can be accessed in the documents section of this page. 

As the design and construction of the Reach A improvement proceeds, further analysis will be conducted to determine if any changes or modifications to the project require additional review under NEPA/CEQA.  This analysis will be contained in subsequent documents as required.

Direct links to the Final EIS/EIR and addendums issued to date are provided below: 
Final EIS/EIR (October 2010)
Addendum No. 1 (April 2018)​
Addendum No. 2 (September 2018)​
Addendum No. 3 (December 2018)​
Addendum No. 4 (May 2019)
Addendum No. 5 (February 2020)​
Addendum No. 6 (May 2020)
Addendum No. 7 (September 2020)
Addendum No. 8 (June 2021)

The existing levee will be widened on the landside along the majority of the Reach A project area (except between Reclamation District No. 1000 office and Gateway Oaks Drive, and under Interstate 80). Widening the levee waterward is not possible primarily because it would reduce the existing channel capacity and presents significant complexities to construct improvements within an inundated channel. SAFCA has already contacted all of the property owners along the entire Reach A project area where real estate acquisition is necessary.

During project construction, residents and businesses should expect temporary traffic detours and delays as a result of construction. Other concerns may include noise, dust, and environmental impacts due to necessary tree removal and levee widening. We are working to minimize or offset all impacts to the extent practicable.

Local levee maintainers need safe and reliable 24-hour all-weather access to the levee to inspect the levees during high water events, deliver heavy equipment and materials to a site that requires flood fighting operations, and of no less importance, to perform routine operations and maintenance of the levee.

No residential structures are being removed solely to accommodate a patrol road. Any residential structures close to the existing levee that have been identified as being in the project footprint are affected by a combination of constructing the necessary levee improvements, establishing required access, and relocating utilities.

Existing City of Sacramento streets that run parallel to the landside toe of the levee, such as along La Lima Way and Avocet Court, can serve as the patrol road. However, clear access along the landside toe of the levee is also required to allow for maintenance of the levee slope. Where no public road abuts the levee, new toe of levee patrol roads will be constructed, which will include a gravel surfacing. The patrol roads will be gated to prevent unauthorized vehicle access into non-roadway areas.

The existing trail access between La Lima Way and Durazno Court will be reconfigured and modified to allow for patrol vehicles to connect between the two streets. The connection will be gated and restricted to authorized vehicle use. A patrol road will be constructed on the west side of Durazno Court, connecting to Orchard Lane. Due to the elevation difference between the levee toe and Orchard Lane, it would not be possible to build a ramp leading up to Orchard Lane without affecting the adjacent residence. A patrol road between Durazno Court and Orchard Lane is required in order to perform ongoing operation and maintenance of the levee and conduct any necessary flood fighting operations. Similarly, a patrol road is required at the east end of La Lima Way connecting to the Garden Highway.

USACE has conducted extensive geotechnical explorations and analyses, hydraulic modeling, and field surveying to determine the type of improvements necessary in each given location around the Natomas Basin. USACE has a high degree of confidence in its project formulation and does not anticipate that a footprint wider than what is currently planned will be necessary to construct the upcoming levee improvements along the Swallows Nest and Brisas del Rio subdivisions.

Site preparation work will be happening along the full 3.5-mile-long extent of Reach A between Farm Rd and Gateway Oaks Dr (see map above). We anticipate construction operations during the hours of Monday-Saturday from 7 a.m. to 7 p.m. Residents can expect increased construction traffic and noise for the site preparation activities. 

Any existing vegetation and trees located within the construction footprint on the landside of the levee will need to be removed. In certain limited areas, such as at the drainage pumping stations and under Interstate 80, removal of waterside vegetation will also be required.  The project will widen the existing levee using engineered fill material, which is compacted on the slope of the levee. It is not feasible to construct the improvements with existing vegetation and trees in place.  Tree and vegetation removal is also necessary to facilitate relocation of existing utilities in advance of project construction.

Trees located on the landside levee slope will need to be removed to accommodate the construction work associated with widening of the levee. (See also the above response). Trees on the waterside slope of the levee are not impacted because the levee widening and slope stability work is occurring on the landside of the levee. The levee widening and slope stability work will consist of adding and compacting engineered fill material on the landside slope. Widening the levee waterward is not feasible primarily because it would reduce the existing channel's river-flow capacity as well as increase construction timelines due to the complexities involved in constructing improvements within a river channel. Current federal and state flood control standards do not permit the planting or establishment of new trees or woody-type vegetation on the levee slope. This standard applies to all levees in the flood control system, including areas where no levee improvements are being constructed. As existing trees reach the end of their life cycle, the establishment of new replacement trees is not permitted on the levee slope. Post levee construction revegetation will consist of planting native grasses on the landside slope to prevent erosion and allow for better visual inspection and maintenance of the levee.

No trees, bushes, vines, or plants that have hard stems can be planted on or within 15 feet of the levee. Grasses will be planted in some areas to compensate for effects to the state-listed Swainson’s hawk. The vegetation will be maintained by RD 1000 over the long-term to ensure they can successfully visually inspect the levee and flood fight (if needed) as required.

As part of the levee improvements, the flood control system will be brought into compliance with current federal, state, and local engineering standards. A very limited number of utility overhead lines will return to the levee crown. Most of the utility poles will be placed outside of the “prism” of the levee and meet local traffic safety utility requirements.

USACE anticipates that those utilities being relocated to allow for construction of the necessary flood risk reduction features will be relocated to the same configuration as they currently exist (i.e., above-ground utilities will remain above-ground).

The Garden Highway roadway will not be widened and will remain two lanes after the project is complete. The widened levee area will consist of gravel surfacing. 

No, USACE will not be constructing any new bike trails as part of the project. However, any existing bike trails or paths that are impacted by construction will be replaced. 

No. When river elevations are high, RD 1000 inspects the waterside levee slope that is above the water surface via Garden Highway. RD 1000 also interprets the presence of waterside erosion by changes to the slope, such as the loss of trees or other improvements, and by watching for eddy currents.  When river elevations are low, RD 1000 inspects the waterside levee slope by working with property owners to coordinate access for walking surveys.

Levee improvements began in 2022 and are expected to continue until Spring 2028. Site preparation activities, which include tree cutting/trimming and utility relocations that are necessary to accommodate levee work, began in Winter 2020. 

The project is being designed and constructed by the U.S. Army Corps of Engineers (USACE) under the WRRDA 2014 American River Common Features, Natomas Basin federal authorization. The Central Valley Flood Protection Board (CVFPB), State of California Department of Water Resources (DWR), and Sacramento Area Flood Control Agency (SAFCA) are the non-federal sponsors. SAFCA and CVFPB are responsible for acquiring any Reach A real estate or right of way required for USACE to construct the project. We have not awarded a construction contract for Reach A levee improvements at this time. 

Specific traffic impacts will not be known until after USACE awards its construction contract, and the contractor develops a construction schedule and traffic control plan. However, it is anticipated that the Garden Highway will remain open in most locations with single lane closures and detours to accommodate single lane traffic.  In certain areas, such as at drainage pumping stations where the discharge pipes need to be modified, temporary full closure of the Garden Highway will be required.  Traffic detours will be implemented at these locations. As traffic control and management plans are approved, information will be provided to the public via the project website at www.natomaslevees.com, email notifications, etc. 

We require our contractor comply with Sacramento Metropolitan Air Quality Management District requirements for equipment emissions and fugitive dust control. Whichever contractor is awarded this project work will be required to employ Best Management Practices (BPMs) throughout all phases of construction to minimize air quality and noise-related impacts. Example BMPs include using dust suppression measures (e.g., regular watering of the project area during earthwork activities) and placing electronic vibration monitors at various locations along the construction area.

USACE will continue to conduct outreach to residents within the project area using a variety of approaches, including direct mailings, community meetings, media outreach, etc. 

Residents can also stay up-to-date with the following resources: 

Project web page: www.natomaslevees.com
Telephone: 916-557-5100
Email: spk-pao@usace.army.mil
Facebook: www.facebook.com/sacramentodistrict
Twitter: www.twitter.com/usacesacramento