Floods present one of the greatest threats to communities in the United States. Flooding is involved in 90% of all natural disasters and every state has experienced a flood in the last five years. In response to the increases in federal disaster relief due to flooding, Congress passed the National Flood Insurance Act of 1968 which created the National Flood Insurance Program (NFIP). The NFIP provides “federally-backed flood insurance available in those states and communities that agree to adopt and enforce flood-plain management ordinances to reduce future flood damage.”

Ultimately, the program incentivizes municipalities to enact various floodplain management and flood mitigation efforts, laid out in the National Flood Insurance Program Community Rating System Coordinator’s Manual, for ‘credit’ that manifests in lower insurance rates. These efforts are grouped into four overarching categories: (1) public information activities, (2) mapping and regulations, (3) flood damage reduction activities, and (4) warning and response. Mapping and regulations make up the most potential credits, with flood hazard mapping offering a maximum of 802—rightfully so, because flood hazard maps provide the foundation for all land use decisions involving flood prevention and mitigation. Flood hazard maps use prediction modeling and data to show how likely it is for an area to flood, providing a critical baseline for land use decision making.

Despite the credits awarded for flood hazard mapping, most local flood hazard maps nationwide are out-of-date and inaccurate. In 2005, the United States Government Accountability Office released a study where they found that at the time of review approximately 92,222 flood maps—nearly 70% of all maps nationally—were more than 10 years old. When these maps are outdated or incorrect, land use decisions are made based on bad data that often results in new development in flood-prone areas and increased risks to life and property. Inaccurate maps are also costing homeowners nationwide billions of dollars. As of 2023, it’s estimated that properties in vulnerable areas are overvalued by $121 billion to $237 billion because flood hazard maps are out of date. When these unacknowledged risks become realized, homeowners stand to lose significant equity, with low-income homeowners suffering the most.

FEMA created both the Risk Mapping, Assessment and Planning program (Risk MAP), formerly the Map Modernization Project, and the Cooperating Technical Partners Program (CTP) to address the issue of outdated flood hazard maps through collaborative partnerships with municipalities. This allows for a more streamlined, cost-effective way for communities nationwide to improve their flood maps and provide a better foundation to inform mitigation and development strategies.

Risk MAP and CTP are intrinsically related. Risk MAP “supports community resilience by providing data, building partnerships, and supporting long-term hazard mitigation planning,” and CTP provides the mechanism for municipalities to have an active role in their own floodplain remapping. CTP was created in 1999 to “help FEMA stretch limited mapping dollars and increase local involvement in the creation for the FIRMs [flood insurance rate maps].” (See pg. 4).

Prior to CTP, the only two ways to revise a flood map were either: FEMA-initiated updates or Community-Initiated revisions, each with significant flaws. FEMA-initiated studies are limited due to funding and capacity issues and only address a select few community maps per year, and community-initiated revisions are dependent solely on local-funding and still do not guarantee that suggested revisions will be made by FEMA. In contrast, CTP partners take on active roles in the Risk MAP program in a variety of ways, including through hydrologic and hydraulic modeling, digital topographic data development, and more. The program also allows for cost-sharing between the municipality and FEMA and incorporates community knowledge and data into the new mapping to achieve more accurate information. In 2021, 81 municipalities nationwide were awarded a total of $101.4M through their CTP partnership. This money helps municipalities update and improve their floodplain maps as well as undertake initiatives to further improve flood mitigation and adaptation.

Pierce County, Washington was one of the first counties to enter the CTP in 1999 after a devastating flood highlighted the inaccuracy of its flood hazard map. To collect more accurate data and update its flood maps, Pierce County relied on a stepped method that is more easily replicable because of its cost-effectiveness and flexibility. First, the county would perform much faster and cost-effective remapping using a method that relies on “updated high-accuracy digital elevation data and detailed digital base maps…combined with existing flood insurance elevation data to redelineate the floodplain boundary and determine new base flood elevations.” (See pg. 24). Essentially, this allowed the county to do a preliminary update before funding was available from FEMA to complete a full hydrologic and hydraulic analysis. The second step, once funding was available, was to perform that more detailed hydrologic and hydraulic analysis. This stepped process required a much smaller initial investment from the county. Since the first step relied on digital base maps and existing data, rather than a complete hydrologic and hydraulic analysis, it was significantly cheaper in the front-end than a typical remapping initiative would be.

This process was directly facilitated by the fact that Pierce County was a CTP partner. Municipalities nationwide can replicate this stepped process and, most importantly, leverage FEMA’s CTP program to update and maintain their flood hazard maps in a more cost-effective and efficient way. The most effective land use decisions to protect communities from the humanitarian and economic disasters caused by flooding rely on accurate flood maps. As the climate crisis worsens and flooding increases, accurate maps have never been more important.

This article is part of a series from the Land Use Law Center that explores how local governments can implement Climate Resilient Development (CRD) as defined in the Sixth Assessment Report of the IPCC. CRD requires innovative reform of land use planning and regulation by local governments. The series presents and analyzes numerous local laws and policies capable of adapting to and mitigating climate change to create equitable and sustainable neighborhoods, achieving “sustainable development for all.” 

Author: Karina Krul, 1L Land Use Scholar