Flood Mitigation


Flooded street after a hurricane.


Floods are the deadliest, costliest and most common form of natural disaster in the United States and in the world. They are caused by hurricanes, heavy rainfall, overflowing rivers, broken dams, overfilled urban drainage basins, tsunamis, water channels with steep sides, and ice- or snow-melt. Floods are difficult to predict, which means states must be prepared to respond at all times.

Forms of Flood Mitigation

Flood mitigation approaches fall into two categories—structural and nonstructural. Structural forms of mitigation mitigate harm by reconstructing landscapes. They include floodwalls/seawalls, floodgates, levees, and evacuation routes.  Nonstructural measures reduce damage by removing people and property out of risk areas. They include elevated structures, property buyouts, permanent relocation, zoning, subdivision, and building codes. Structural solutions have lost popularity over time as old dams and floodgates have failed.

New Orleans flood mitigation.FEMA released a report in 2017 called "Innovative Drought and Flood Mitigation Projects" that evaluates four disaster mitigation approaches highlighted by an EPA-commissioned report: "Aquifer Storage and Recovery, Floodwater Diversion and Storage, Floodplain and Stream Restoration, and Low Impact Development (LID)/Green Infrastructure (GI)." The report assesses each approach based on cost, efficacy, feasibility and fulfillment of Hazard Mitigation Assistance (HMA) requirements.

The report finds that all four options are consistent with HMA’s requirements and guidelines and will effectively mitigate the impact of climate disasters, including floods. Aquifers are primarily used to mitigate the impact of droughts, so the following descriptions focus on the other three recommendations. 

  • Floodwater Diversion and Storage - Diverting floodwaters into wetlands, floodplains, canals, pipes, reservoirs, or other conduits helps mitigate flooding by allowing for a controlled release of water outside of residential or metropolitan areas.  At least 16 states have enacted legislation since 2010 establishing intent, programs, or funds to build floodwater diversion or storage systems.
  • Floodplain and Stream Restoration – Floodplains and streams not only mitigate the risk of floods but can also mitigate bank erosion and benefit local ecosystems. Floodplains store stormwater runoff, reducing the number of floods and their severity.  10 states have passed legislation to restore streams or floodplains to mitigate flood damage since 2010. 13 bills have failed in the United States Congress concerning floodplain restoration since 2010. Five more are pending. 
  • Low Impact Development (LID)/Green Infrastructure (GI) – LIDs and GIs mitigate the risk of floods by storing water. They tend to mimic natural hydrology and include innovations such as green roofs and permeable pavement. Most states have implemented some form of LID or GI. 

State Action

At least 19 states and Puerto Rico enacted legislation in 2019 related to flood mitigation.

US map showing states that enacted flood legislation.


2019 Enacted State Legislation


Bill Number



2019 HB 1148

Appropriates $997,075 for flood hazard mitigation grants.


2019 SB 99

Requires a city or county, upon the next revision of its housing element, to include information identifying residential developments in hazard areas that do not have at least two emergency evacuation routes.


2019 HB 1292

Continues the Colorado Resiliency Office. Repeals the requirement that the office be funded solely through grant funding, making general funds available. 


2019 SB 221

Appropriates $500,000 from the Colorado water conservation board construction fund to continue the floodplain map modernization program.


2019 SB 1062

Authorizes municipalities to establish climate change and coastal resiliency reserve funds that can be used to fund payments for property losses and land acquisitions due to climate change.


2019 HB 329

Amends the Kauai Flooding Disaster Relief Appropriation Act to include flood mitigation measures.


2019 HB 1558

Requires the Office of Planning to update the Hawaii 2050 Sustainability Plan using the Hawaii Climate Change Mitigation and Adaptation Initiative as guiding principles.


2019 HB 2737

Provides that the purposes of soil and water conservation districts include the improvement of resilience to droughts, floods, and other extreme weather.


2019 SB 638

Establishes a flood recovery fund to support local projects related to flood response, recovery or mitigation activities. 


2019 HB 285

Appropriates $1 million from the General Fund to the Water Management Account for flood risk reduction and flood prevention projects, among others.


2019 HB 62

Appropriates $10 million from the Capital Development Fund to the Department of Natural Resources for implementation of flood hazard mitigation plans. 


2019 HB 142

Appropriates $375,457,000 for capital facilities projects related to water resource management, including flood mitigation.


2019 HB 407

Amends growth planning and land use laws to reflect that addressing the effects of sea-level rise is a state planning and regulatory goal.


2019 HB 428/SB 269

Authorizes the Maryland Department of the Environment, under its existing comprehensive flood management grant program, to award grants to subdivisions that have incurred at least $1 million in infrastructure damage by a flood event that occurred on or after January 1, 2009. Requires the Governor to include in the annual state budget an appropriation of at least $5 million for the program.


2019 HB 101

Appropriates $5 million split between Annapolis, Ellicott City and Baltimore for projects which reduce the risk of loss of life and property from flooding. Grant funds may be used to acquire flood-prone properties, install flood warning systems, and construct flood control projects.


2019 HB 1427

Alters the application of certain design and siting criteria established by the Coast Smart Council to apply only to certain state and local capital projects. Extends the date the projects must comply with the criteria and the date certain local jurisdictions must develop a plan to address certain nuisance flooding. Requires the Department of Planning to develop guidelines to assist local jurisdictions in data collection.


2019 SB 35

Establishes the Nevada Resilience Advisory Committee and charges the group with, among other things, developing state resilience goals and formulating recommendations and policies regarding statewide mitigation, preparedness, response and recovery efforts.

New Hampshire

2019 SB 285

Authorizes municipalities to create municipal development and revitalization districts as a result of a climate change emergency. Establishes the Coastal Resilience and Cultural and Historic Reserve Commission.

New Jersey

2019 AB 4751

Appropriates $3.054 million to acquire, for recreation and conservation purposes, properties throughout the state that are prone to or have incurred flood or storm damage, or that may buffer or protect other lands from such damage as part of the Blue Acres program.


2019 SB 1073

Authorizes counties, municipalities, and certain authorities to establish stormwater utilities and related fees and other charges. 

New York

2019 SB 6599

Adopts a host of measures to put the state on a path to reduce statewide greenhouse gas emissions by 85% by 2050 and net-zero emissions in all sectors of the economy.


2019 SB 431

Creates the Urban Flood Safety and Water Quality District in a portion of Multnomah County for purposes of managing and improving the levee system, drainage and natural areas to provide for flood safety and contribute to water quality, habitat, and landscape resiliency.

Rhode Island

2019 HB 5484

Revises the definition of building height by including in special flood hazard zones those areas identified on the sea level rise map as being inundated during a one-hundred-year storm.


2019 SB 994

Expands the definition of the approved project to include resiliency related infrastructure projects and projects which may include state and federal infrastructures within the state.


2019 SB 7

Amends the existing floodplain management account to create the Texas Infrastructure Resiliency Fund, which houses four accounts: floodplain management account, Hurricane Harvey account, flood plan implementation account, and federal matching account. Also requires a report from agencies that utilize federal dollars.


2019 SB 8

Requires the Texas Water Development Board (TWDB), not later than September 1, 2024, to prepare and adopt a comprehensive state flood plan. Requires TWDB to designate flood planning regions corresponding to each river basin and provide technical and financial assistance to the groups.


2019 SB 563

Requires a state agency that uses or disburses federal money for flood research, planning, or mitigation projects to submit a report on a quarterly basis to the state Water Development Board.


2019 HB 2345

Creates the Institute for a Disaster Resilient Texas as a component of Texas A&M University to develop data analytics tools to support disaster planning, mitigation, response, and recovery and create and maintain web-based tools to communicate disaster risks and ways to reduce those risks.


2019 SB 1082

Establishes a joint interim committee to continue to study the feasibility of creating and maintaining a coastal barrier system that includes gates and barriers to prevent storm surge damage to gulf beaches or coastal ports, industry, or property.


2019 SB 285

Sets forth requirements for information and outreach regarding hurricane preparedness and mitigation. Requires the reports of state agency preparedness for hurricane responses to be published on the Governor's Office website.


2019 SB 289

Creates a Disaster Recovery Task Force to operate throughout the long-term recovery period following disasters by providing specialized assistance for communities and individuals to address financial issues, federal assistance programs, and recovery and resilience planning.


2019 SB 1588

Codifies an amendment to the Constitution of Virginia adopted in Nov. 2018, which enables a locality to provide by ordinance a partial exemption from real property taxes for flooding abatement, mitigation, or resiliency efforts for improved real estate that is subject to recurrent flooding. 

Puerto Rico

2019 SB 773

Orders the approval of a Mitigation and Adaptation to Climate Change Plan by sectors. Establishes the Joint Commission on Mitigation and Adaptation to Climate Change of the Legislative Assembly.


Federal Mitigation Legislation

Spring 2019 Disaster Aid Package

In June, Congress passed a long-awaited $19 billion supplemental disaster aid package for states most affected by 2017, 2018 and 2019 disasters. Disaster mitigation sections included:

  • $1 billion in Flood Control and Coastal Emergencies account for expenses to prepare for flood, hurricane, and other natural disasters, as well as support certain emergency response operations.
  • Nearly $800 million to the Army Corps of Engineers to investigate and build high-priority flood and storm damage reduction projects.
  • $2.4 billion in Community Development Block Grant funds, in part requiring any remaining funds to be used for mitigation activities.
  • $50 million to the National Oceanic Atmospheric Administration to improve forecasting.
  • $50 million for Title IX funds for public-private partnership to support coastal resiliency.

Fall 2018 Disaster Recovery Reform Act

Congress passed HR 302, the Disaster Recovery Reform Act (DRRA) in October 2018. Considered the most comprehensive disaster reform legislation since Hurricane Katrina, the new law covers the full spectrum of disaster phases but specifically increases the federal investment in predisaster mitigation.

DRRA establishes the Building Resilient Infrastructure and Communities program, which will commit certain funding from the Disaster Relief Fund to predisaster mitigation efforts. It allocates 6% of the combined obligations estimated following a major disaster—unemployment assistance, assistance to low-income migrant and seasonal farmworkers and crisis counseling assistance and training—to mitigation assistance (Section 1234). That 6% is made available the following year on a competitive basis for states that have experienced a major disaster in the last seven years to use for mitigation projects. Mitigation funding is also provided for wildfire prevention (Section 1204).

Important for states, Section 1239 of the law also directs the FEMA administrator to revise and update the factors considered when evaluating a governor’s request for a major disaster declaration, including the way FEMA estimates the cost of major disaster assistance based in part on the capacity of a jurisdiction to respond to disasters.  

NCSL drafted and advocated for language in the final law that specifically requires consultation with state and local governments:

“In determining the capacity of a jurisdiction to respond to disasters, and prior to the issuance of such a rule, the Administrator shall engage in meaningful consultation with relevant representatives of State, regional, local, and Indian tribal government stakeholders.”

The inclusion of this language ensures that FEMA considers this important perspective before making changes to the way disaster assistance is calculated, based on such capacity. This language reflects NCSL’s current Homeland Security and Emergency Management policy, which in part promotes consultation as well as mitigation-focused policy. NCSL issued a letter to the full Senate in July of 2018 highlighting certain components of the legislation and advocating for its passage. If you have any further questions on federal mitigation policy, please contact Lucia Bragg or 202-624-3576. 

For questions pertaining to legislation in your state, please email Kim Tyrell

Additional Resources

FEMA Programs

  • Innovative Drought and Flood Mitigation Projects, FEM final report., Jan. 2017.
  • Significant Flood Events, FEMA, June 2018. On this page, you will find a data table detailing flooding events with 1,500 or more paid losses from 1978 to the current month and year. The table includes the name and year of the event, the number of paid losses, the total amount paid, and the average payment per loss.
  • Flood Mitigation Assistance Grant Program, This is the Flood Mitigation Assistance Grant Program (FMA) homepage. The purpose of this page is to provide general information on the FMA program.
  • Hazard Mitigation Grant Program, This page contains information about the FEMA Hazard Mitigation Grant Program (HMGP). The purpose of this program is to connect individuals and state, local, and tribal government representatives with the resources they need to implement hazard mitigation measures in their communities.
  • Pre-Disaster Mitigation Grant Program, This is the FEMA Pre-Disaster Mitigation Grant Program (PDM) homepage. The purpose of this page is to provide general information on the PDM program.