Lower Cache Creek Flood Risk Reduction Project
Cache Creek, located north of the City of Woodland, carries water from Clear Lake and the Coast Range into the Cache Creek Settling Basin (north and east of I-5) and eventually into the Yolo Bypass. The creek has a long history of flooding and has overtopped its banks and levees more than 20 times since 1900 because existing levees only provide approximately a 10-year level of flood protection, meaning the levees have a 10 percent chance of failing in any given year.
Most recently, the Cache Creek levees overtopped in February 2019. If not for flood fighting actions, portions of Woodland could have flooded.
Lower Cache Creek downstream of CR 102 looking east (February 2019)
The Federal Emergency Management Agency (FEMA) provides Flood Insurance Rate Maps (FIRMs) which show their determination of the boundaries of a 100-year flood. A "100-year" flood has a 1/100 chance of occurring in any given year. The map below indicates which parts of Woodland are in the Cache Creek 100-year floodplain, with flood depths ranging from one to ten feet within Woodland.
Approximately 1,000 Woodland properties are mapped into this area, including residential areas and much of Woodland's industrial economy. As of December 2023, 779 residential addresses are currently in the floodplain.
In addition, a flood event would close I-5 and impact the City’s wastewater treatment facility, requiring costly repairs and limiting the facility's ability to treat wastewater. Drinking water supply may also be impacted because key roads would flood.
Background & History
For many years, the City has aimed to develop a flood control project to increase safety, provide an economically feasible and environmentally sensitive solution, meet state and federal requirements, and reduce flood insurance costs for residents and property owners.
In 2000, the City initiated a study of its options and considered five different flood control plans. Following consideration of these options, the City approved the Lower Cache Creek Flood Barrier (“Flood Barrier”) in 2003. The Flood Barrier project received public opposition for its failure to adequately address impacts to properties north of the City.
In 2011, the City once again attempted to study and undertake a flood control project. The City evaluated approximately 26 alternatives to reduce flood risk, some of which were modified and/or combined with other alternatives, and convened the Woodland Flood Control Advisory Committee, which considered the options and made recommendations. After consideration of the alternatives, the City Council ultimately adopted Resolution No. 7651 in February 2021, certifying the Final Environmental Impact Report and approving the Lower Cache Creek Flood Risk Management Project, the current project described on this webpage.
The project features a set of structural solutions, including a levee and water conveyance channel north of town, and non-structural solutions, such as assistance to property owners north of the levee. The current project is a marked change compared to the 2003 proposal described above.
First, the project is part of a regional set of projects to improve flood protection. This coordinated strategy did not exist when the 2003 project was proposed. Examples of other regional projects include:
- Cache Creek Channel and Levee Rehabilitation Project
- Lower Elkhorn Basin Levee Setback Project
- Sacramento Weir Widening Project
- Yolo Bypass Salmonid Habitat Restoration and Fish Passage Project
- Fremont Weir Adult Fish Passage Modification Project
- Additional planned projects in the Lower Sacramento River/Delta North Regional Flood Management Plan
Second, the project includes measures intended to improve performance as compared to the 2003 plan. In relation to the previous proposal, the project intends to:
- Reduce flood duration for all properties in the floodplain
- Reduce flood depth for the majority of the floodplain
- Eliminate Cache Creek flooding impacts on Interstate 5
- Offer flood easements to properties that may experience deeper flooding
Third, the project’s features differ significantly from the previous plan, including:
- Flood conveyance under SR 113 and I-5
- Underseepage protection
- A flood conveyance channel intended to avoid worsening flood impacts
- Improved weirs and culverts to move flood water out of the area
- A detention basin intended to assist drainage and decrease flood duration
Effects of Being in a Floodplain
Any new building (or building undergoing significant remodeling) within the above 100-year floodplain must comply with special provisions in the Building Code, primarily that the first floor must be above the base flood elevation.
These properties are also subject to mandatory flood insurance, which can cost several thousand dollars per year for a single-family residence. These properties will remain within the floodplain until a project is constructed to provide at least 100-year flood protection, which is the minimum level required by FEMA.
Final US Army Corps of Engineers (USACE) Lower Cache Creek Feasibility Study
The City, the Central Valley Flood Protection Board (CVFPB), the California Department of Water Resources (DWR), and the USACE coordinated on a feasibility study to identify a locally-supported plan to increase flood protection to the City and adjacent critical infrastructure, like Interstate 5 and the City's Wastewater Treatment Facility. The feasibility study started in late 2013 and was completed in June 2021, which led to the development of the USACE Lower Cache Creek Flood Risk Reduction Project.
What’s Being Done to Reduce Risk?
The USACE Lower Cache Creek Flood Risk Reduction Project would provide a 200-year level of flood protection to the City of Woodland, which is a State of California requirement for urban areas. The City is maximizing opportunities for state and federal funding to increase the chances that this project is constructed.
Concurrent with the USACE’s feasibility study, the City prepared the Environmental Impact Report (EIR) for the Lower Cache Creek Flood Risk Management Project. As described above, this EIR was certified in February 2021. The project expands upon the USACE’s plan by adding measures to reduce flood stages and duration of flooding for agricultural properties north of the City. Actions for these properties could include raising or flood proofing structures, establishing flowage easements, and subsidizing flood insurance.
The City analyzed property values and other concerns for the lands north of the City that would remain in the floodplain in the "North Area Appraisal Report" below, prepared by Bender Rosenthal. The independent analysis found that no land, including properties north of town, will experience a decrease in property value.
- North Area Appraisal Report
- Woodland Flood Risk Management Project Final Environmental Impact Report
- Woodland Flood Risk Management Project Draft Environmental Impact Report
Cache Creek Floodplain & Project Map
Areas in green would be removed from the floodplain as a result of the project. Areas in blue would remain in the floodplain. Areas in darker green would be removed from the 100-year plain but remain within the Yolo Bypass floodplain.
The public comment period for the USACE Lower Cache Creek Draft Feasibility Study closed on February 10, 2020. Study documents can be reviewed and downloaded below.
- Lower Cache Creek Draft Feasibility Report
- Lower Cache Creek Draft Supplemental Impact Statement
- Lower Cache Creek Draft Supplemental Impact Statement – Appendices
City Council Action
At the October 17, 2023 Woodland City Council meeting, Councilmembers voted to place Measure M on the March 5, 2024 ballot. This measure seeks voter input and approval to move forward with the Flood Project. City staff and Councilmembers believe it would be beneficial to obtain certainty via the ballot that the City is enabled to receive federal and state financial support for the Project by giving the voters a chance to amend Woodland's municipal code. A full staff report is available here.
Lower Cache Creek emergency levee work (February 2019)