Flood Hazard Management

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Salish Sea References

• Watershed Characterization Mapper
• The Encyclopedia of Puget Sound
• PRISM Project Search
• Washington Coastal Atlas
• WDFW's Salmonscape Map

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Flood Hazard planning, mitigation, response, and recovery is the result of interactions between multiple agencies. The result of this interaction has a very strong impact on the future landscape condition in Floodplains. Flood Attenuation is one of the most highly valued ecosystem services provided by Salish Sea watersheds and floodplains. The development of floodplains, provokes the need for flood hazard management.

Flood Management Topics

6 Topics in Flood Management

Executive Order 11988  •  Flood fencing  •  Integrated Floodplain Management  •  Letter of Map Revision  •  No Rise and The Letter of Map Revision  •  River Delta Flood Management and Drainage

Flood Hazard Planning and Preparations - Before the Flood

• Counties are generally most directly engaged in flood management . They own the majority of roads, build and maintain flood control infrastructure, are responsible for permitting building in floodplains, and answer to state and federal regulators for many of these decisions, often by integrating floodplain related ordinances into county code. Flood authority is typically housed within a Public Works department.
• County authority may be delegated to flood control district that can impose fees, and own and maintaining local flood infrastructure. Different flood districts may engage in "levee wars" where each district attempts to construct its flood defenses so that a neighboring districts levees will fail first.
• Counties develop a Comprehensive Flood Management Plan under RCW 86.12. Ecology used to provide funding for plan development, but the Flood Control Assistance Account Program was largely defunded in the early 2000s. Many counties have very old flood management plans, and most public funding in the flood system is spent reacting to flood disasters.
• Residential development in floodways is prohibited in state law. Ecology can file suit against individuals for violations of state law.
• Ecology has a new authority Floodplains by Design to provide grant assistance for flood hazard reduction that also achieves salmon recovery and other ecosystem goals.
• Ecology regional flood staff complete county Assistance Visits to review consistency of county policy with NFIP and State law, and reports violations to FEMA.
• The Growth Management Act administered by Washington State Department of Commerce defines critical areas, including Frequently Flooded Areas and requires consideration of channel migration zone in development of Comprehensive Plans.
• Public Benefit Rating System or other open space incentive program can be used to create tax incentives for limiting development in frequently flooded areas.
• Executive Order 11988 defines the responsibilities of all federal agencies in considering flood risk management.

The FEMA Connection

• The FEMA National Flood Insurance Program (NFIP) sets standards for participation in the program, develops model ordinances for floodplain management (See FEMA 2013), and evaluates community readiness through a Community Rating System that evaluates measures taken by communities to reduce flood hazards and meet other federal requirements (like implementing the Endangered Species Act). This recent integration of ESA and flood management occurred through a Biological Opinion published by NOAA describing how implementation of the NFIP affects chinook salmon populations, through enabling floodplain development.
  • The FEMA NFIP BiOp describes the conditions under which the Washington NFIP is consistent with ESA, but not resulting in adverse modification of habitat. Toward that end, the program requires no loss of
  • FEMA has a Flood Hazard Mapping Program that defines the "FEMA Floodplain and Floodway" in Flood Insurance Rate Maps (FIRMs), and the rate schedule that determines your National Flood Insurance Program rates. Floodplain can be both coastal or riverine, and the maps differentiates between "floodways" and "floodplains".
  • No Rise and The Letter of Map Revision - Limits on development are intended to prevent damage claims to NFIP, and those limits are implemented in county ordinance. As part of that compliance floodplain restoration projects are required to analyze how a project changes flood elevation, potentially resulting in a requirement to redraw the flood hazard map.
• The FEMA Hazard Mitigation Grant Program provides around $25-100M/year to do acquisition or project work to reduce future flood damages, and it is administered by the Washington State Military Department

The USACE Connection

• Approximately 10% of levees nationally are directly managed by the USACE.
• The USACE PL 84-99 Levee Rehabilitation and Inspection Program enrolls levees in an inspection program. Participation in the program provides federal support during floods and with repairs if the levee is damaged during a flood. This is a huge incentive for small jurisdictions to participate in the program.
• The USACE System Wide Improvement Framework or "SWIF" is a planning process required to correct deficiencies in a PL 84-99 inspection. A risk-based plan is developed to address those deficiencies and remain active in the PL 84-99 program.
• King County and Whatcom County have expanded the SWIF process to use it for a larger flood hazard management planning process.

Flood Observation and Response - During the Flood

• The Washington State Military Department Emergency Management Division, implements flood hazard response for the state in close collaboration with local jurisdictions. EMD maintains a State Flood Hazard Mitigation Plan, reviewed by FEMA, which is required for federal support.
• USGS maintains river gauges that provide real time water level measures.
• NOAA makes river flow predictions based on predicted future precipitation, and describes these in terms of flood.
• Emergency response is supposed to be protective of aquatic habitat and fish life as determined by NOAA. USFWS and WDFW, however this is one of many often conflicting considerations during emergency flood response.

Flood Recovery - After the Flood

• FEMA provides federal funds through Washington State Military Department to support states and local jurisdictions with flood hazards.
• FEMA funds can be used to buy out property that results in hazards. Ecosystem service value can be included in cost effectiveness analysis leading to buyout under FEMA 2013.
• A federal disaster declaration determines whether federal funds from FEMA become available for post-flood recovery.
• Recovery of public infrastructure depends on the jurisdiction that owns the bridge or road or levee in question. Participation in PL 84-99 can offset reconstruction costs.
• How are NFIP claims processed?

Flood System Reform

• The majority of resources are spent reacting to flood events. County flood staff are often few in number. Programs to support analysis, modelling and planning are limited in the flood system. Channel aggregation has been reducing flood system effectiveness over time in many systems. Climate change is anticipated to increase peak flow, and increase sediment load, exacerbating flood hazard in many systems.
• Floodplains by Design envisions flood control that is integrated with natural resource management. Flood levee setbacks and other "green infrastructure" decisions both reduce flood hazard and restore habitats in large rivers. This approach is proposed to have a higher public benefit for the cost than continued augmentation of levees and dredging, particularly under climate change.
• Pierce County Levee Setback Planning is perhaps the most advanced example of a levee setback planning process in the Salish Sea.
• Lower Nooksack System Wide Improvement Framework is developing strategies for flood system design and restoration downstream of Ferndale on the Nooksack Watershed.
• The USACE does not have a national policy for inclusion of climate hydrology data in flood planning. Many agencies fail to include cutting edge model analysis in this planning. At FEMA there is a difference between "effective" flood maps, which are legally binding, and "preliminary" flood maps, that could be used to reflect future projections.

Example Materials

• http://www.floods.org/Files/Conf2014_ppts/H5_Robinson.pdf

All Workgroups and Efforts in Flood Management

  Workgroups

• Counties
• Federal Emergency Management Agency
• French Slough Flood Control District
• Washington State Department of Ecology
• Washington State Military Department

  Efforts

• Automating Landscape Connectivity for Puget Sound River Deltas and Pocket Estuaries
• Building Resilient Infrastructure and Communities (BRIC)
• Effects of Exposed Tidal Flats on Water Temperature in the Snohomish Estuary
• Flood Hazard and Ecosystem Management Coordination
• Floodplain Permit Streamlining Workgroup for Nooksack
• Floodplains by Design (FbD)
• Lower Skykomish Floodplain Land Strategy
• Puget Sound Coastal Storm Modeling System (PS-CoSMoS)
• Puget Sound Large River Delta Tidal Restriction and Wetland Mapping
• Puget Sound Tidal Restriction and Wetland Mapping
• Skagit Farm, Fish and Flood Initiative
• Snohomish Estuary Restoration Effects on Temperature, Salinity, and Tides
• Snoqualmie Fish, Farm & Flood Initiative
• Snoqualmie Fish, Farm and Flood Initiative
• Stillaguamish Delta Dynamics Affecting Restoration

Flood Management Products

The following Product pages are categorized with Flood Management.

  Documents

Brouwer et al 2015 floodplain early opportunities  •  Earth Economics 2013 pierce county flood return on investment.pdf  •  Elefant et al 2019 stillaguamish flood control district sedimentation and subsidence  •  Greene et al 2012 effects of tidegates on fish  •  Katz et al 2022 flood attenuation and restoration puyallup white  •  Konrad 2015 ecological function flood risk puget sound floodplains  •  Mauger & Kennard 2017 climate change and flood hazard management  •  SDHP 2014 skagit hydrodynamic model report  •  Smith et al 2005 tide gate salmon recovery analysis skagit  •  Snohomish County 2015 hazard mitigation plan  •  Turner et al 2004 stillaguamish flood hazard management plan.pdf  •  Weinerman et al 2012 fisher slough economic benefits.pdf  •  Yang et al 2011 model flood and tide

  Websites & Datasets

  Graphics

facts or skills acquired by a person through experience or education.

a unit of government with specific authorities, or the area in which those authorities can be legally exercised

particles of clay, silt, sand, gravel, or cobble, transported by water, are called sediment.