Flooding Issues

Flood Safe 2.0

Yolo County and partner agencies are undertaking numerous projects to help reduce flood risk across the county. These projects include topographic mapping, vegetation maintenance, channel improvements, hydrologic studies, various construction initiatives to help improve drainage, and more.

Madison Community Flood Risk Reduction
Madison Community
Rolling Acres Region
Guinda
Yolo
City of Winters
DQU & New Indian Health Services Facility
Highway 16 between Madison & Esparto
County Road 95 Airport
Huff's Corner
Six-Pac near Winters
Expand flood monitoring systems(SCADA)
Graveling access roads
Flow station at Salisbury Spill and connect to NWS
Create detention retention and or infiltration at strategic locations
Small-scale storage in Western Foothills
Traffic Control Coordination
On-Farm Temporary Storage

View the detailed Project List Document for more information

Huff's Corner Levee Raise & Channel Reconfiguration Project

The Project was developed by Yolo County and is funded through a cost-share grant administered by the DWR via their Flood System Repair Program (FSRP) – Contract Number 460013693. While the majority of costs to design and construct the Project are funded by FSRP, Yolo County provides a significant share of costs in the form of direct expenditures and in-kind services with multiple Yolo County Staff. There are two distinct components of this Project. The first is the levee “raise,” which is more accurately described as a restoration action to return the levee to the original design height. The second component is the Cache Creek channel reconfiguration. Both components are fully analyzed and discussed in greater detail in this IS/MND.

Documents:

Project Description

Levee Work - Design Plans

In-Channel Work - Design Plans

CEQA Compliance:

Notice of Intent

Adoption Memo

Initial Study / Final Mitigated Negative Declaration

Mitigation Monitoring and Reporting Program

Notice of Determination

Knights Landing Flood Management Project

In 2017, Yolo County received a grant from the California Department of Water Resources (DWR) Small Community Flood Risk Reduction Program (SCFFRP) to complete a feasibility study of structural and non-structural actions that could reduce flood risk to Knights Landing. The County prepared the 2019 Knights Landing Small Community Flood Risk Reduction Feasibility Study.

In 2020, the County received additional grant funding from DWR as part of Phase 2 of the SCFRRP to implement the Knights Landing Flood Management Project, which includes four project elements:

The design of levee improvements along the Sacramento River adjacent to Knights Landing, the design and permitting of the Knights Landing Ridge Cut levee, and the design and permitting of the Mid-Valley Levee Reconstruction to include the construction of Site 9 & 10.
Completion of Phase 1 concepts for Portuguese Bend and Grays Bend Habitat enhancement projects.
The design, permitting, and construction of the Drainage Infrastructure Improvements.
The design of the New Cross Levee and New Cross Levee Loop Trail.

When the Knights Landing Flood Management Project is completed, it will reduce or prevent flooding to a population of 995, approximately 321 structures, and 3,500 acres of prime agricultural lands.

Sacramento River Right Bank Levee Improvements

The proposed Sacramento River Right Bank Levee improvements would address under-seepage, through-seepage, stability, and freeboard deficiencies. To address under- and through-seepage, from levee mile 0.0. to 0.75 adjacent to the community of Knights Landing, an 80-foot-deep clay cutoff wall would be installed through the center of the existing Sacramento River Right Bank Levee. The construction area would extend approximately 0.75 miles along the Sacramento River Right Bank Levee. Additional improvements along the Sacramento River Right Bank Levee are proposed downstream of Knights Landing to address seepage. Seepage areas would be addressed by either constructing seepage stability berms or cutoff walls. For the construction of cutoff walls, the existing levee would need to be degraded by half its height for the installation of the cutoff wall, and then rebuilt. Large earthmoving construction equipment would be used to complete the improvements. The levee will be reconstructed to meet current levee standards and attain a 100-year design surface water elevation. The construction work area would include an access corridor on the landside toe of the existing levee. All construction staging and material stockpiling would occur along the levee as construction progresses down the levee and would take place within the construction work areas. Access to the construction work areas would be from the levee or County Road 116B. The construction work area would include an access ramp up onto the existing levee. No residents would be displaced as a result of the proposed seepage improvements. While some private parcels may be affected, no buildings or structures would be removed.

Knights Landing Ridge Cut Improvements

The proposed Knights Landing Ridge Cut improvements would occur southwest of Knights Landing and would include clearing and grubbing of trees and vegetation, excavating the face of the existing landside levee slope, and reconstructing the levee with imported fill to widen the levee crown and create a consistent elevation along the levee. The proposed improvements on the landside of the Knights Landing Ridge Cut Levee would also include remediation of existing levee encroachments, including but not limited to removal of levee pipe penetrations, relocation of PG&E power poles, and replacement of levee gates. The finished levee crown elevation would be reconstructed a minimum elevation of 43 feet.

Large earthmoving construction equipment would be used during construction. The proposed improvements can be accessed via existing levee ramps and temporary earthen ramps. Proposed haul routes include Locust Street and existing agricultural/farm roads. These access routes would be used by two-way traffic. The proposed haul routes are currently used as agricultural roads and may require grading or crushed rock surface to be placed in order to support construction vehicles. Construction staging areas would be located, to the extent practicable, away from sensitive resource areas and known cultural resources. Construction staging and material stockpiling would occur along the levee as construction progresses down the levee. A wider area within the northwest portion of the proposed construction area would likely be used for parking construction trailers and vehicles. No residents would be displaced as a result of the proposed improvements to the Knights Landing Ridge Cut Levee. While some private parcels may be affected, no buildings or structures would be removed.

Portuguese Bend Multi-Benefit Enhancement Area

The Portuguese Bend multi-benefit enhancement area would protect and restore habitat in line with the objectives of the CVFPP 2017 Update within an approximately 136-acre area located between the levees of the Sacramento River known as Portuguese Bend. Situated southeast of Knights Landing and along the eastern perimeter of the Knights Landing Basin, the habitat improvements within Portuguese Bend include controlling invasive plant species, planting native species, and implementing an ongoing management and monitoring program. The native species to be planted would replicate and enhance the existing native habitat within the area including the existing mixed riparian forest, riparian willow forest, emergent marsh, and tule marsh plant communities. The planting would be implemented appropriate to the site’s topography and hydrology to ensure the long-term viability of the enhanced plant communities. The use of heavy equipment is not anticipated; passenger vehicles and light trucks would be used to facilitate planting. Access to the work areas would be from County Road 116B. Staging would occur either on top of the levee or on the exposed areas and dirt roads that are located on the site. No residents would be displaced as a result of the proposed freeboard and seepage improvements. While some private parcels may be affected, no buildings or structures would be removed.

Drainage Infrastructure Improvements

The proposed project would incorporate roadside ditch improvements along 2nd Street between the Post Office and Railroad Street to improve storm water drainage capacity; a buried closed conduit under Railroad Street between 2nd Street and 4th Street (approximately 2.25-foot-wide by 1-foot-deep); an open channel along the east side of Railroad Street between 4th Street and 7th Street (approximately 3-foot-deep, 2:1 side slopes); removal of the existing concrete arch culvert; and degrade of the abandoned railroad embankment using a 50-foot-wide open cut channel.

Mid-Valley Sites 9, 10, and 11 and Widened Parking Area near Wild Irishman Bend

The proposed project is to construct slurry cutoff walls in the existing Sacramento River right bank levee at Sites 9 and 10 to address through seepage, and construct a combination berm at Site 11 to address stability, and under- and through-seepage. The purpose of the project is to reduce flood risk to the Knights Landing Basin while sustaining agriculture and the regional economy, providing safe access to the Sacramento River, and improving riverine habitat viability.

North Fork Putah Creek Fuel Reduction Project

This project consists of removal of wildfire fuels (e.g., dead trees/vegetation, downed woody debris, ladder fuels, and dense dry stand of shrubbery) from the North Fork Putah Creek channel, located between Drummond Avenue and Mace Boulevard in Davis, CA.

The County will be contracting with the California Conservation Corps to perform the work at no cost to the County. Mature, healthy trees will not be affected by the project, unless structural issues are identified that could jeopardize public safety, such as cracked or dead limbs.

All vegetation to be removed is marked with color-coded non-toxic, washable paint. The project area will be surveyed by a certified wildlife specialist not less than 3 days prior to work commencing. County staff have confirmed with the California Department of Fish and Wildlife that no permits are required for the work.

The project is located along the southern boundary of the City of Davis' Willowcreek subdivision, north of the Willowbank and Old Willowbank subdivisions in unincorporated Yolo County. The existing drainage channel is a remnant of the Putah Creek system, which was aligned to divert floodwaters into the South Fork of Putah Creek in the late 19th century. The North Fork of Putah Creek is currently used by the City of Davis for storm water conveyance, though most of the project area is on county-owned property. The project area is approximately 9 acres in size.