Seawalls are not generally recommended because they limit the migration and the transfer of sediment that is critical to the long-term sustainability of coastal marshes. Seawalls may accelerate erosion at the ends of the structure.
But in situations where no other viable alternative is readily available, it may be possible to construct a seawall in or adjacent to a coastal marsh to protect property in proximity to an eroding bank. An individual permit will be required from Maine DEP in order to pursue construction of a seawall that impacts a coastal marsh, but generally Maine DEP will not approve the use of a seawall in most coastal wetland areas.
Additionally, new seawalls are not allowed in coastal sand dune systems.
Both of the photos below are from the same cove. The photo on left shows property where a wall was constructed many years ago. The photo on the right shows property without walls where an extensive wetland persists and buffers the residence from the waves.