The Water Management division of Humboldt County Public Works is responsible for:
- Managing three levee systems (Redwood Creek, Mad River, Sandy Prairie)
- Assisting with technical studies and planning related to flood management and sea level rise adaptation
- Administering municipal stormwater programs for McKinleyville and Shelter Cove
- Representing Humboldt County on water and fishery issues related to the Klamath and Trinity Rivers
- Coordinating stakeholders in the Eel River Valley on sustainable groundwater management
- Representing Humboldt County on various restoration and water resource initiatives
- Levee and Flood Management
- Stormwater Program
- Sea Level Rise
- Klamath Settlement Agreements
- Special Projects
The Federal Emergency Management Agency (FEMA) develops Flood Insurance Rate Maps (FIRMs) as a tool for identifying flood risks. Areas mapped as Zone “A” (Special Flood Hazard Area) on a FIRM are subject to special building standards and may be subject to flood insurance requirements by lending institutions. FEMA is in the process of updating the FIRMs for Humboldt County to more accurately characterize flood risk. The FEMA flood maps are being updated in two phases:
Phase 1: New FIRMs become effective on November 4, 2016. This update reflects the results of detailed flood studies in certain areas, changes in the vertical datum, and conversion to a digital platform. These maps are available at the FEMA Map Service Center and the Humboldt County Web-GIS.
Phase 2: Flood maps along the coast will be updated in mid-2017 to reflect the results of FEMA’s Open Pacific Coast Study, which was an engineering study to evaluate coastal flood hazards. The preliminary maps are available for review on this site Coastal Flood Maps Coastal Flood Maps Coastal Flood Maps Coastal Flood Maps Coastal Flood Maps Coastal Flood Maps Coastal Flood Maps Coastal Flood Maps.
Resources:(PDF 3.6 MB)
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The Jacobs Avenue Levee is situated along Humboldt Bay between the Highway 101 Eureka Slough bridge and Airport Road. The one-mile-long levee provides flood protection for 31 parcels within Eureka city limits. The Jacobs Avenue Levee does not have a single owner; rather, multiple property owners own portions of the levee adjacent to their respective properties. Humboldt County owns a 3.2-acre parcel behind the levee which serves as the County’s vehicle maintenance facility and heavy equipment yard.
In 2014, Humboldt County (acting as the Humboldt County Flood Control District) initiated a technical study of the Jacobs Avenue Levee to assess the stability of the levee and its associated flood risks, and to determine whether the levee meets FEMA’s certification standards. Funding for this study was provided by the California Department of Water Resources, Humboldt County, City of Eureka, and affected private landowners along Jacobs Avenue, with laboratory testing performed by Caltrans.
The Flood Control Project is impaired by the deposition of large volumes of sediment, which has reduced the project’s flood capacity from the level of protection specified by Congress. Construction of the levees also reduced the ability of North and South Sloughs to flush sediment, which contributes to flooding of adjacent privately owned pastures and public roads. A fundamental rehabilitation of the Flood Control Project is needed to accommodate sediment inflow and achieve an acceptable level of flood protection that can be sustained with normal maintenance. Improvements are needed to regain active status in the Corps of Engineers Rehabilitation and Inspection Program and achieve certification and accreditation on the FEMA Flood Insurance Rate Map.
Construction of the Flood Control Project caused major physical changes to the lower reach of Redwood Creek and its estuary. Estuary volume has been reduced by over one-half of its pre-levee size due to sediment deposition, and fish habitat and water quality have been severely impaired. The net result has been a reduction in the ecological function of the estuary in terms of productivity and survival of fish and other aquatic species. Restoration of hydraulic, sediment transport, and floodplain processes is needed to help the estuary regain some of its former form, function, resiliency, and productivity.
In 2014, Humboldt County completed a planning study which developed conceptual designs for a multiple-objective project on lower Redwood Creek and estuary that would achieve estuary restoration and levee rehabilitation. Funding was provided by the California Department of Fish and Wildlife (formerly Department of Fish and Game) through the Fisheries Restoration Grant Program. The approach to this planning study focused on facilitating stakeholder dialogue and improving the understanding of natural processes, desired conditions, and potentially feasible project concepts.
The Mad River Flood Protection Project is located near the confluence of the Mad River and the Mad River North Fork, along the right bank of each waterway for a total length of 1.6 miles, near the Hatchery Road bridge at the southern end of the city of Blue Lake. The levee was constructed in phases by the Army Corps of Engineers starting in 1954 and reaching completion in 1963. The levee is composed of an earthen embankment with rock-slope protection on the river side. Humboldt County and the City of Blue Lake share responsibility for levee operation and maintenance.
In 2015, Humboldt County and the City of Blue Lake completed a geotechnical investigation with financial assistance from the California Department of Water Resources to characterize subsurface soil conditions and analyze levee performance. The project assessed the stability of the levee embankment and foundation and evaluated the potential for settlement, seepage, underseepage, or erosion to cause instability under base flood (1%-annual-chance flow) conditions.
Technical memorandum with supporting hydraulic information
The Eel River Flood Control Project at Sandy Prairie is located along the right bank of the Eel River, with extensions along Strongs Creek and the Van Duzen River, near the city of Fortuna. The levee was constructed by the Army Corps of Engineers and completed in 1959. The total length of levee is approximately four miles.
Humboldt County Public Works administers a stormwater management program to reduce the discharge of pollutants to the storm sewer systems and associated receiving waters as regulated by the federal Clean Water Act through the National Pollution Discharge Elimination System (NPDES) permit program.
Working Together on the Humboldt Bay
The County of Humboldt is collaborating with the City of Eureka and the Humboldt Community Services District in the development of the Eureka Area Watershed Storm Water Resource Plan (EAWSWRP). The EAWSWRP is a regional storm water planning document that facilitates a watershed-based analysis and planning effort within watersheds that drain to Humboldt Bay. The EAWSWRP is intended to maximize cooperation and collaboration among state, regional, and local agencies, and other stakeholders during the identification, development, and implementation of storm water projects.
Municipal Stormwater Permit and Low Impact Development Standards
In February 2013, the State Water Resources Control Board adopted the current version of the “MS4 Permit” which applies to stormwater discharges from small municipal separate storm sewer systems (MS4s). The purpose of the MS4 Permit is to control the discharge of pollutants to storm sewer systems which ultimately drain to natural waterways. The state has stipulated that the MS4 Permit applies to McKinleyville, the unincorporated Eureka area, and Shelter Cove (County of Humboldt Phase II MS4 Boundary Maps).
The MS4 Permit requires that the County require certain development projects to comply with post-construction stormwater requirements based on “low impact development” standards. These standards are intended to maintain a site’s pre-development runoff characteristics by using design techniques that capture, treat, and infiltrate stormwater on site. These standards will be effective starting July 1, 2015.
The MS4 General Permit specifies two size classes for post-construction requirements. Projects that create and/or replace 2,500 to 5,000 square feet of impervious surface (“small projects”) will need to implement one or more designated site design measures to reduce project site runoff. Examples of site design measures include disconnection of rooftop drainage from impervious areas, tree planting and preservation, rain barrels, vegetated swales, and porous pavement. Projects that create and/or replace 5,000 square feet or more of impervious surface (“regulated projects”) will need to implement site design measures based on more detailed procedures and demonstrate compliance with runoff reduction thresholds. Some projects may be required to construct bioretention facilities. In addition, projects in the larger size category will need to comply with source control measures to minimize the contact between pollutants and stormwater runoff.
Procedures, standards, and specifications for implementing the post-construction requirements of the MS4 Permit are contained in the Humboldt Low Impact Development Stormwater Manual V2.0. This manual will also be used by the Cities of Eureka, Arcata, Fortuna, and Trinidad for compliance with the MS4 Permit. Humboldt LID Stormwater Manual V2.0 and associated documents are available on the North Coast Stormwater Coalition website.
North Coast Stormwater Coalition
Humboldt County participates in the North Coast Stormwater Coalition which coordinates regional storm water management efforts. A toll free regional stormwater hotline operated by the North Coast Stormwater Coalition can be called at 1-707-2STORM2 to report active pollution or other stormwater concerns.
The North Coast Stormwater Coalition works collaboratively with North Coast California county and city governments to reduce stormwater pollution and protect local watersheds. Coalition members include stormwater management staff from the participating Cities of Arcata, Eureka, Fortuna, Ft. Bragg, Trinidad and Yreka, the Counties of Humboldt and Mendocino, and Humboldt State University, as well as representatives of other local, state, and federal agencies, non-profit organizations, tribes, the CA State and Regional Water Boards, consultants, engineers, and interested community members. We are a robust group that meets monthly, with public education and outreach events and workshops occurring throughout the year.
More information is provided on the North Coast Stormwater Coalition website.
Documents for Viewing and Download:
- County of Humboldt Phase II MS4 General Permit Boundary Maps
- Storm Water and the Construction Industry - Best Management Practices Poster
- Humboldt Low Impact Development Stormwater Manual V2.0
The following State and Federal websites contain technical and regulatory information regarding Municipal, Construction, and Industrial stormwater programs and stormwater pollution prevention resources.
- California State Water Resources Control Board – Stormwater Programs Webpage
- US EPA Stormwater Homepage
Sea Level Rise Adaptation Plan for Humboldt Bay/Eureka Slough Area (2018-2020)
Humboldt County received funding from the Caltrans Adaptation Planning Grant program to support the preparation of a sea level rise adaptation plan for the Eureka Slough hydrologic sub-unit of Humboldt Bay. This area includes segments of Highway 101, county and city roads, railroad, and the future Humboldt Bay Trail, along with Murray Field airport, utility transmission lines (gas, electrical, water), wastewater pump stations, and a mix of industrial, commercial, residential, agricultural and wildlife land use. Due to ground surface elevations, exposure to wind waves, and the condition of levees and embankments, this area is especially vulnerable to flooding hazards, with vulnerability expected to increase due to the progressive rise of sea levels.
The Eureka Slough area spans multiple municipal jurisdictions, and a variety of stakeholders including City of Eureka, HCAOG, Caltrans, North Coast Railroad Authority, California Department of Fish & Wildlife, the Humboldt Bay Harbor, Recreation and Conservation District, Humboldt County Farm Bureau and Pacific Gas & Electric Company desire to participate in regional collaboration for adapting to sea level rise. The City of Eureka and the Humboldt County Association of Governments were subapplicants for the grant, which is funded through Senate Bill 1, the Road Repair and Accountability Act of 2017.
The project will prepare an adaptation plan that identifies the specific flooding vulnerabilities within the planning area and develops adaptation project concepts, with an emphasis on stakeholder engagement, multi-benefit goals, best available scientific information, cost-effectiveness, and strategic planning. The project is expected to be completed in June 2020.
Schedule Opens a New Window. (October 10, 2018)
Humboldt Bay Sea Level Rise Adaptation Planning Project (2010-2015)
The Humboldt Bay Sea Level Rise Adaptation Planning Project Opens a New Window. was active from 2010 through 2015 and conducted two phases of regional collaborative planning with funding from the California State Coastal Conservancy.
Caltrans District 1 Climate Change Vulnerability Assessment – Main Document Opens a New Window. (December 2014) (PDF 3 MB)
Caltrans District 1 Climate Change Vulnerability Assessment – Appendices Opens a New Window. (December 2014) (PDF 22 MB)
Humboldt Bay Area Plan Update
Humboldt County is a signatory party to the Klamath Hydroelectric Settlement Agreement and Klamath Basin Restoration Agreement, a set of agreements signed in February 2010 with the intent of providing a framework for resolving the most contentious disputes involving dams and water diversions in the Klamath River basin. The Klamath River flows through Humboldt County for approximately 60 miles of its 263-mile-long course. The presence of dams on the upper Klamath River (three in Siskiyou County and one in Oregon) have cut off fish habitat and adversely affected water quality, which has contributed to declining fish runs and caused fishery closures. Humboldt County’s primary interests in the Klamath settlement process have been to improve Klamath River stream flow conditions, protect the county’s commercial and recreational fishery interests, and alleviate the hardships to fishing and tribal communities.
Resources for additional details:
Humboldt County supports the Salt River Ecosystem Restoration Project, a collaborative effort between private landowners, non-profit organizations, and local, state, and federal agencies to restore fish habitat, improve water quality, and alleviate flooding impacts. The Salt River project is distinctive for the scale of the restoration, the complexity of the issues, and its commitment to being community- and partnership-based. The project encompasses the Salt River, Francis Creek, and Williams Creek which suffer from severe sedimentation and hydraulic dysfunction. The project is coordinated by the Humboldt County Resource Conservation District.
Humboldt County Public Works provided technical assistance from 2007 through 2009 with funding from the State Coastal Conservancy .
Humboldt County Public Works operates a monitoring station on Francis Creek at Van Ness Avenue in Ferndale. The station collects continues data for water stage and turbidity and has an auto-sampler to collect water samples for laboratory testing of suspended sediment - Data are available on-line. The data are analyzed to develop annual loading estimates to support planning and design for the Salt River Ecosystem Restoration Project and county road maintenance activities.
Mad River Bluff Streambank Protection Project:
Humboldt County Public Works completed a bioengineering streambank stabilization project in 2008 along the right bank of the lower Mad River, with funding from USDA-Natural Resources Conservation Service, the Governor’s Office of Emergency Services, and adjacent landowners.
Humboldt County Public Works is coordinating the local response to the Sustainable Groundwater Management Act, which was signed by Governor Brown in September 2014. The legislation applies to groundwater basins designated as medium- or high-priority by the California Department of Water Resources. In June 2014, DWR designated one medium-priority basin (Eel River Valley) and no high-priority basins in Humboldt County. In May 2018, DWR released draft basin prioritization results which identified Eel River Valley and Mad River Valley-Mad River Lowland as medium-priority basins. The public comment period ended on August 20, and the final prioritizations are expected to be released in November.
- DWR Basin Prioritization Webpage
- Humboldt County Comment Letter (August 20, 2018) for Eel River Valley
- Humboldt County Comment Letter (August 20, 2018) for Mad River Valley-Mad River Lowland
Eel River Valley Groundwater Working Group
The Eel River Valley Groundwater Working Group was convened in October 2015 to guide the local response to the Sustainable Groundwater Management Act. The purpose of the Working Group, as revised on September 12, 2016, is to:
- Provide information and viewpoints regarding groundwater issues in the Eel River Valley.
- Support the collection and analysis of technical data and information to understand conditions and trends.
- Discuss selection and formation of a Groundwater Sustainability Agency (GSA), if applicable.
- Discuss the framework and sustainable management criteria for an Alternative Submittal or future Groundwater Sustainability Plan (GSP).
Eel River Valley Groundwater Basin Groundwater Sustainability Plan Alternative Submittal
- Groundwater Sustainability Plan Alternative December 2016 (PDF 442 KB)
- Groundwater Sustainability Plan Alternative Appendices (PDF 80.5 MB)
- Groundwater Sustainability Plan Alternative Figures (PDF 52.3 MB)
- Groundwater Sustainability Plan Alternative Figures reduced file size (PDF 17.1 MB)
A total of 18 Groundwater Sustainability Plan Alternatives were submitted across the state. The Department of Water Resources expects to complete their review by Fall 2018.
- February 24, 2015: Staff Report and Presentation to the Board of Supervisors.
- April 27, 2015: Workshop on groundwater in the Eel River Valley (Workshop Announcement, Presentation, and Summary).
- May 20, 2015: Presentation to the Eel River Forum.
- October 6, 2015: Staff Report to the Board of Supervisors.
- October 21, 2015: First Working Group meeting (Agenda and Meeting Materials and Minutes).
- December 14, 2015: Second Working Group meeting (Agenda and Meeting Materials and Minutes).
- February 22, 2016: Third Working Group meeting (Agenda and Meeting Materials and Minutes).
- April 25, 2016: Fourth Working Group meeting (Agenda and Meeting Materials and Minutes).
- September 12, 2016: Fifth Working Group meeting (Agenda and Meeting Materials and Minutes).
- November 7, 2016: Sixth Working Group meeting (Agenda and Meeting Materials and Minutes).
- December 2, 2016: Seventh Working Group meeting (Agenda and Meeting Materials and Minutes).
- December 13, 2016: Humboldt County Board of Supervisors Agenda Item to adopt a resolution authorizing Public Works to submit a Groundwater Sustainability Plan Alternative.
- December 20, 2016: Eighth Working Group meeting (Agenda and Meeting Materials and Minutes)
- March 22, 2017: Presentation to the Eel River Forum.
- May 3, 2018: Presentation to the Humboldt County Farm Bureau.
- June 21, 2018: Ninth Working Group meeting (Meeting Materials)
- All meetings take place at the University of California Cooperative Extension office located at 5630 South Broadway, Eureka, CA.