States Shift From Seawalls to Living Shorelines

The 2018 U.S. National Climate Assessment estimates that, over the next century, sea levels may rise between two and six feet, and possibly by as much as eight feet, threatening densely populated coastal communities, vulnerable beaches, and wetland habitats with inundation, erosion, and shoreline loss.

In response, states are incorporating adaptation and coastal resiliency into their planning and permitting regimes.

Coastal states have embraced an array of protective and adaptive approaches, including traditional hard-armoring structures such as seawalls and bulkheads, as well as “living shoreline” strategies that employ natural materials, such as sand and vegetation to stabilize eroding beaches and enhance wetland habitats.

Some states have embraced more aggressive efforts such as increasing setback requirements and abandoning or relocating existing shoreline development, referred to as “managed retreat.”

We surveyed current state regulatory responses to sea level rise and shoreline protection in 22 U.S. coastal states (including the Gulf of Mexico states, Alaska and Hawaii) and eight states adjacent to the Great Lakes, and found that the majority of these—21—have endorsed living shorelines or other “soft” coastal resiliency approaches in statute, regulation, state policy or guidance.

Thirteen states have adopted some form of statewide shoreline setback requirements.

While all states continue to allow construction of seawalls and other forms of hard-armoring structures to protect coastal properties in some circumstances, all but two of those surveyed impose regulatory restrictions on such structures. One state, North Carolina, has banned construction of new, permanent coastal erosion control structures, with certain narrow exceptions.

Of the 30 states surveyed, only two—Alaska and Louisiana—appear to have no statewide regulations or policies applicable to shoreline armoring or living shorelines. 

A. States Push Back Against Structural Shoreline Armoring

Seawalls, bulkheads, revetments, and other armoring structures remain a significant means of protecting coastlines from the effects of erosion, extreme weather, and sea level rise. All coastal states allow shoreline property owners to maintain or replace existing armoring structures, and to construct new structures, under at least some circumstances.

However, 28 of the surveyed states impose permitting criteria and restrictions on shoreline armoring structures, with the effect of generally discouraging them except under specified conditions and/or where no feasible alternative is available.

The New Jersey Department of Environmental Protection, for example, approves construction of new or expanded shore protection structures only if they are essential to protect water-dependent uses or existing development, will not exacerbate erosion, and will cause minimum feasible adverse impacts to living marine resources.

Similarly, the Washington Department of Ecology regulations allow shoreline stabilization structures only where they are necessary to protect legally existing shoreline structures or uses endangered by erosion, and if nonstructural measures, such as setbacks, planting vegetation, or installing on-site drainage improvements are infeasible or insufficient.

At the other end of the spectrum, North Carolina has banned new permanent ocean shoreline armoring structures altogether, subject to narrow exceptions for certain structures previously approved by the state Coastal Resources Commission, or structures in continuous use since 1974 to protect inlets maintained for navigation.

Other states prohibit hard structures within specified shoreline areas.

South Carolina, for example, has banned most new construction or reconstruction of armoring structures seaward of a defined setback line (the sand dune crest in most areas). In several states, use of armoring structures for new development is restricted, but older development is “grandfathered” by legislation or regulations.

The California Coastal Commission allows beachfront protective structures for development that existed on or before 1976 (when the state Coastal Act took effect) but prohibits new protective devices for structures built after that date.

Similarly, in Massachusetts, construction of coastal engineering structures including seawalls, bulkheads, and revetments on or adjacent to coastal banks is prohibited unless doing so is necessary to protect buildings constructed prior to 1978. 

B. A Shift Toward Living Shorelines

“Living shoreline” definitions and projects vary, but generally feature natural materials such as shrubs, trees or sand, often in combination with harder structural materials such as stone, wood or oyster shells. By providing a natural buffer against wave action, living shoreline projects are intended to stabilize coastal areas against the effects of sea level rise, while also providing shoreline habitat for wildlife.

In 2015, the National Oceanic and Atmospheric Administration issued nationwide guidance for the implementation of living shoreline projects, encouraging their use for shore stabilization along sheltered coasts and supporting living shorelines in preference to hardened armoring where appropriate.

The U.S. Army Corps of Engineers’ Nationwide Permit 54, a general permit issued in 2017 under the federal Clean Water Act, authorizes the construction and maintenance of living shorelines to stabilize banks and shores in coastal waters. Among other things, living shorelines permitted by the Corps must “maintain the natural continuity of the land-water interface, and retain or enhance shoreline ecological processes” and include a “substantial biological component.”

Thirteen states have codified living shoreline policies and other “soft” protection approaches by statute or in regulations.

For example, in Maryland, the 2008 Living Shorelines Protection Act provides that, where feasible and appropriate, coastal erosion protection efforts generally must consist of nonstructural shoreline stabilization measures that preserve the natural environment.

The act declares living shorelines to be “the preferred method of shore protection” and allows structural protection measures only under specified circumstances, such as where the living shorelines approach is not feasible. Hard armoring structures may be constructed within areas identified by state as appropriate for structural stabilization measures, but construction outside those areas requires a waiver from the Maryland Department of the Environment.

In Washington, Department of Ecology regulations favor nonstructural methods of shoreline stabilization, including structure relocation, setbacks, vegetation enhancement, anchor trees, and gravel placement as alternatives to hard armoring.

Some states have adopted streamlined permitting processes to encourage living shoreline projects, such as the New Jersey Department of Environmental Protection’s statewide General Permit 24, which allows certain habitat restoration and living shoreline activities that are less than one acre in size and disturb the minimum amount of land necessary to implement the project.

In eight states without relevant statutes or formal regulations, agencies have developed policies and guidance encouraging living shoreline approaches. For example, in 2017, the New York Department of Environmental Conservation issued guidance on implementing living shoreline techniques in the state’s marine areas, emphasizing natural solutions for coastal erosion control and encouraging natural shoreline protection measures in place of hardened or man-made approaches. Similarly, the Indiana Department of Natural Resources’ Coastal Hazards Planning Guidance recommends living shorelines as the preferred option for property owners experiencing erosion issues. 

C. The Next Level: Managed Retreat

“Managed retreat” encompasses a range of more aggressive approaches, such as limiting replacement of structures destroyed by erosion or flooding, and relocating existing structures out of hazard zones. Some states have also implemented “buy-back” programs to purchase properties in high-risk coastal zones. For example, New York instituted a large-scale buy-back program in Staten Island following Hurricane Sandy.

Managed retreat is generally considered to be a new and often controversial concept in response to climate change and attendant sea level rise. However, it is worth noting that traditional setbacks from the mean high tide line or a similar fixed point, widely utilized by state and local governments long before shifting sea levels began to receive attention, may have the same (albeit unintended) effect: as mean high tide rises, fixed setbacks will migrate landward toward existing development.

Thirteen of the surveyed coastal states have adopted some form of statewide shoreline setback requirements. For example, Wisconsin’s shore protection program regulations require all buildings and structures to be set back a minimum of 75 feet from the ordinary high-water mark of navigable lakes, rivers and streams. Similarly, New Hampshire and Florida generally prohibit new construction within 50 feet of the mean high tide line without a permit or variance.

Several states have adopted variable “rolling” shoreline setbacks. Maine’s coastal sand dune regulations prohibit new development on property reasonably expected to be severely damaged due to erosion and flooding within 100 years due to sea level rise. In other states, adjustable setbacks may not be so explicitly premised on rising seas, but similarly tend to result in retreat over time. For example, Delaware’s Beach Preservation Act prohibits new construction seaward of the building line, which may be adjusted based on storms and other natural phenomena. North Carolina imposes shoreline setback requirements based on the vegetation line and annual average rates of erosion.

In California, the state Coastal Act gives cities and counties primary authority to develop Local Coastal Programs (LCPs) governing development within their coastal areas, but subjects the LCPs to review and approval by the California Coastal Commission. In 2018, the Commission released policy guidance on residential adaptation and incorporating coastal resiliency policies into LCPs. The guidance encourages local governments to consider managed retreat as an alternative to shoreline protection, to allow structural armoring only if feasible alternatives do not exist, and to phase out existing armoring structures that are no longer necessary to protect shoreline uses.

More than 40 California coastal cities and counties are updating their LCPs to include sea level rise adaptation plans. However, some local governments and shoreline property owners have objected to the Commission’s emphasis on managed retreat. In October 2018, the Del Mar City Council passed a resolution rejecting the state policy as unnecessary and infeasible due to “economic, environmental, engineering, social, political, and legal constraints and uncertainties” including the prohibitive cost of public acquisition of shoreline private property and risks of removing existing shoreline protection structures. The Commission is now reviewing the city’s sea level rise adaptation plan.

While some state and local governments and landowners will similarly resist abandoning existing development to its fate, coastal states confronting rising seas and extreme weather are being pressed to find new ways to cope. Most states likely will continue to permit coastal armoring structures in some circumstances, as a necessary tool to protect vulnerable shoreline development already in place.

Nevertheless, the shift away from hard armoring structures as the default solution, and toward living shorelines and managed retreat, is a growing trend.