Shoreline Erosion Control: Walls, Riprap and Living Shorelines

Every eroding shoreline raises the same first question: what is the least you can build that will still hold the land? The answer depends on wave energy, water depth, the slope of the bank, how much room you have, how you use the waterfront and what your neighbors have built. It also increasingly depends on state policy, since some coastal states now treat a vertical wall as a last resort rather than a default.

This overview compares the main options. For the forces that drive erosion in the first place, see waterfront erosion explained.

The green-to-gray continuum

NOAA and the U.S. Army Corps of Engineers describe shoreline stabilization as a continuum. At the green end are vegetation and other natural or nature-based features. At the gray end are hard structures such as bulkheads, seawalls and revetments. Between them are hybrids such as sills with marsh plantings. Their joint brochure, produced through the Systems Approach to Geomorphic Engineering (SAGE) community of practice, frames the choice around site conditions: wave energy, fetch, slope and the rate and pattern of erosion.

The main options

Bulkheads and seawalls

The SAGE brochure describes a bulkhead as a vertical retaining wall parallel to the shoreline, intended to hold soil in place, and a seawall as a structure built to absorb and limit the impact of large waves. Vertical walls fit sites with deep water at the edge, existing hardened neighbors or a need for boat access. The VIMS shoreline management report adds an important caution: vertical faces reflect wave energy and can scour out the bottom at the toe, so scour depth must be accounted for in design. See bulkhead vs. seawall.

Revetments and riprap

A revetment lays stone or other armor over a sloped bank. VIMS notes that the sloped, rough face reduces wave reflection and toe scour compared with vertical walls, and that a properly designed and constructed rock revetment can last fifty years or more. It also describes what goes wrong: undersized stone, a single layer of armor or too steep a slope can lead to failure after a modest storm. A typical design uses two layers of armor stone over bedding stone, with filter cloth on the soil.

Sills

A sill is a low, usually rock structure placed along the shoreline, often with marsh planted behind it. VIMS describes sills as combining elements of rock revetments and offshore breakwaters. The SAGE brochure notes that sills dissipate wave energy, protect the edge of wetlands and provide habitat, and that gapped designs allow better tidal exchange and access.

Living shorelines and vegetation

NOAA Fisheries defines a living shoreline as a nature-based method for stabilizing a shoreline using materials such as plants, sand, rock or oyster shell. NOAA's 2015 guidance highlights that, unlike seawalls and bulkheads, living shorelines do not need to create a barrier between land and water. Vegetation alone is the softest option, and the SAGE brochure notes it is appropriate only in limited, low-energy situations.

Pros and cons at a glance

Advantages and drawbacks summarize those listed in the NOAA and Army Corps SAGE brochure and the VIMS report. Every site differs.

Where states prefer living shorelines

Maryland

Maryland's Living Shoreline Protection Act of 2008 requires that improvements to protect property against erosion consist of nonstructural shoreline stabilization measures, such as marsh creation, unless the owner shows the Maryland Department of the Environment that such measures are not feasible. The law lists areas of excessive erosion, heavy tides and areas too narrow as examples. MDE's page states that living shorelines are the preferred method of shore protection and that a structural project needs an approved waiver, available where the shoreline is mapped as appropriate for structural measures or where site conditions make a living shoreline unsuitable.

Virginia

Since July 1, 2020, Virginia law directs the Marine Resources Commission to "permit only living shoreline approaches to shoreline management unless the best available science shows that such approaches are not suitable." Where a living shoreline is not suitable, applicants must incorporate living shoreline elements to the maximum extent possible, and wetlands applications must include a statement on suitability.

North Carolina

North Carolina took a permitting route. In 2019 the Division of Coastal Management began issuing a general permit for marsh sills, a type of living shoreline, to streamline approvals. The state described living shorelines as alternatives to bulkheads and revetments, and reported that after Hurricane Florence, marsh sills outperformed nearby bulkheads by dissipating wave energy and reducing erosion.

Federal permits

At the federal level, the Army Corps maintains a nationwide permit for living shorelines (NWP 54). The current set of nationwide permits took effect March 15, 2026. Regional conditions vary by Corps district. See our bulkhead permit guide.

Choosing an approach

1. Characterize the site. Wave exposure, fetch, water depth, bank height and erosion rate drive what can work.
2. Define the need. Boat access, usable yard, flood concerns and budget all matter.
3. Look at neighbors. The SAGE brochure warns that projects must consider the overall sediment system so neighboring shorelines are not starved of sand.
4. Talk to regulators early. In some states the preferred option is set by law.
5. Compare designs, not labels. A well-designed hybrid can outperform a poorly built wall or marsh.

To compare materials and approaches side by side, use the material explorer. For more on stone and nature-based options, see riprap and living shorelines.