Implementing the Limit of Moderate Wave Action in Coastal Communities

In coastal communities across the country, residents may not know their property is at risk from wave damage.

On FEMA flood maps, the Special Flood Hazard Area (SFHA) shows high-risk areas that would be affected by the 1%-annual-chance flood (or base flood). Within the SFHA, Zone VE is the zone closest to the shoreline. Zone VE is used on flood maps to indicate areas where wave action and fast-moving water can cause extensive damage during the base flood event, with wave heights of 3 feet or higher. FEMA’s National Flood Insurance Program (NFIP) requires stricter floodplain management and construction requirements for structures in Zone VE to account for these hazards.

However, decades of post-storm observation have shown FEMA that waves as small as 1.5 feet can significantly damage buildings that were not built to withstand wave hazards. FEMA developed the Limit of Moderate Wave Action (LiMWA) to show communities where waves greater than 1.5 feet high may cause damage. Where available, the LiMWA line on coastal flood maps marks the inland limit of the Coastal A Zone.

Zone VE floodplain management and construction standards are not required in the Coastal A Zone, but they are strongly recommended.  

Due to the higher risk of damage to homes and other structures from waves in the Coastal A Zone, FEMA encourages the practice of implementing Zone VE standards to better protect structures from wave damage. Building to stricter and more protective codes and standards in the Coastal A Zone can reduce the impacts of future flood and storm events. There are additional benefits to communities that take these actions, including potential eligibility for discounted flood insurance premium rates through FEMA’s Community Rating System (CRS) program.

FEMA has developed this resource to highlight several coastal communities that have successfully reduced their flood risk by adopting these higher standards. Some key considerations are given based on their experiences that could benefit other communities.

The Town of Babylon is on the southern shore of Long Island and participates in the NFIP. In 2009, they were one of the first communities to adopt effective flood maps that included the LiMWA. In 2012, the town saw firsthand the damage waves can cause during Hurricane Sandy.

Three years later, the State of New York updated the state building code to require that communities regulate the Coastal A Zone to Zone VE standards. Babylon already had Zone VE on their maps and were familiar with the building codes and standards required, but this change meant that they had to apply and communicate the stronger codes and standards to a broader area. Recognizing the benefits of adopting the higher standards, Babylon held workshops through the New York State Floodplain and Stormwater Managers Association and worked with its building department to directly communicate the updated standards to developers and architects in the area. The town’s proactive outreach and engagement generated a positive outlook by the community about the more stringent regulations. Because of these higher standards, new or substantially improved properties in areas that were once exposed to sunny day or high-tide flooding are now better protected.

The City of Long Beach is on a barrier island off of Long Island, New York. During Hurricane Sandy, the community was flooded from both the Atlantic Ocean and the bayside surrounding the city. There was damage throughout the entire community, with 6 feet of sand covering the city center.

Before Hurricane Sandy, the city had never experienced such a powerful storm, and resilience was not a priority for residents or community leaders. This all changed after the storm. In the recovery immediately following Hurricane Sandy, the city’s first priority was to assist residents in rebuilding and returning to their home and reopening businesses.

Long Beach has both AE and VE zones on the community’s effective flood map. City officials made changes to the zoning code to allow for higher building heights as homes were being raised to meet FEMA requirements. When adopting new zoning code regulations, the city found that timing their message about the importance of stronger building codes was critical. 

Plans were also put into place to protect the city by rebuilding the ocean-side boardwalk with storm protection and protecting dunes through a U.S. Army Corps of Engineers program. On the bayfront, grants from FEMA and the Department of Housing and Development funded new bulkheading and pumping stations. 

As a leader in Long Island in resilience, the city has worked hard to achieve and maintain a level of 7 in the Community Rating System program to reduce flood insurance costs.  This was done through the development of a strong Floodplain Mitigation Plan with the support of city departments, community leaders and the public.

FEMA, the State of Maryland and local communities developed the Maryland Model Floodplain Management Ordinance to integrate National Flood Insurance Program requirements with state permitting requirements. Many communities decided to adopt this model ordinance, including Cecil County.

The state’s model ordinance was updated to reflect Coastal A Zone requirements after the state began receiving flood maps with a Limit of Moderate Wave Action in the mid-2010s. Any new housing or other development (or substantial improvement of existing structures) must follow V Zone standards if they are located channelward of the LiMWA. This includes construction standards such as open foundations and limited size enclosures constructed with breakaway walls. Despite the fact that some areas are experiencing higher high tides and the effects of extreme rainfall, many residents did not realize that damage from waves was possible before Cecil County adopted the updated ordinance.

The consideration of wave effects raised the cost of construction projects in the Coastal A Zone, which caused some initial resistance from residents and home builders. In 2020, the county was affected by Tropical Storm Isaias and experienced more than 6 inches of rain in less than 24 hours. Because Cecil County adopted the ordinance, new construction was minimally impacted by the nuisance flooding caused by the storm, demonstrating to residents the value of building to higher standards.

Though the Limit of Moderate Wave Action and Coastal A Zone do not have the same National Flood Insurance Program regulatory requirements as VE Zones, communities should consider requiring higher codes and standards to reduce risks from wave damage. By building homes in the Coastal A Zone to VE Zone standards or higher, communities reduce their risk.

Elevating homes and installing flood vents can help mitigate the effects of other flood risks such as high-tide flooding or extreme rainfall. To successfully adopt and implement higher codes and standards in the Coastal A Zone, communities should consider:

• Education – It is important to encourage early awareness and support from local officials, like city planners and building permitters, and from the construction industry, which includes developers, architects, designers and contractors. These are the key stakeholders applying for and approving permits for renovations and new construction. They’re also responsible for adhering to the higher codes and standards. Outreach to these groups should be a priority for any community adopting Coastal A Zone standards.

• Tailor the outreach - Local officials, construction industry professionals, and residents may all have different interests in the regulations. For example, homeowners need to understand the value of an upfront investment, while the construction industry needs to understand the technical components of the codes and standards. Communities should develop trainings and other resources tailored to the needs of these different audience groups and their needs.

• Timing and messaging – When adopting Coastal A Zone standards, communities should consider their recent flood experiences. Messaging about the value of the new standards may be different in a post-disaster context, where immediate needs like food, shelter and water come first. But as communities rebuild, outreach and education about the value of the higher codes and standards can help residents realize the value of building back stronger so that when another storm hits, they can get back in their homes faster. The town of Babylon found that images can be powerful and persuasive tools for showing stakeholders the importance of building back stronger. Some communities may be able to use photographs from previous flood events in their community or communities like theirs, to show homeowners how buildings built to higher standards performed during severe storms.