Bulkheads & Seawalls on Long Island

Long Island's South Shore is a chain of shallow bays, marsh islands and residential canals behind the Atlantic barrier beaches. In communities such as Freeport, Baldwin, Long Beach and the Town of Babylon, bulkheads separate homes and yards from tidal water. This page focuses on the South Shore of Nassau and western Suffolk counties, with notes on the rest of the island.

The waterfront environment

Back bays behind the barrier islands

From west to east, Hempstead Bay, South Oyster Bay and the Great South Bay sit behind Long Beach, Jones Beach Island and Fire Island. Jones Inlet and Fire Island Inlet connect them to the ocean. The Town of Hempstead's Department of Conservation and Waterways reports that it oversees 17,000 acres of wetlands and 180 miles of coastal waterways. DEC notes that tidal wetlands line much of Long Island's salt water shore, bays, inlets and canals.

Tide range drops with distance from the inlets

NOAA tidal datums show how the barrier islands damp the ocean tide:

A bulkhead near an inlet sees several feet of water rise and fall each tide, with stronger currents. One deep in the Great South Bay sees about a foot. On the North Shore, western Long Island Sound has a much larger range again. These differences affect toe scour, drainage through the wall and how much of the face is exposed at low water. See seawall drainage and soil stabilization behind seawalls.

Soft bay bottoms

The Town of Hempstead requires bulkhead applicants to submit a minimum of three probings to determine the depth of a bog. Soft organic soils affect how deep sheeting and piles must be driven and how a wall's toe and anchors perform. A licensed engineer or marine contractor determines embedment for a specific site. The steel sheet piling guide explains embedment concepts.

Storm history

Hurricane Sandy in October 2012 is the most significant recent flood event documented for the South Shore. The National Hurricane Center reported:

• A high-water mark of 4.6 feet above ground level in Freeport, in the Town of Hempstead.
• Marks of 4.3 feet in Inwood and 3 to 4 feet elsewhere in Nassau County.
• A high-water mark of 5.6 feet above ground level on Fire Island and 5.5 feet at Oak Beach-Captree.
• A storm surge of 5.89 feet above normal tide levels at Montauk and 12.65 feet at Kings Point on western Long Island Sound, the highest measured by an NOS gauge in New York.

NHC noted that southward-facing shores of Long Island also took powerful, damaging waves on top of the surge. Overtopping, loss of fill behind walls and damage to caps and tiebacks are common results of an event like this. Review signs of bulkhead failure and the bulkhead inspection guide.

Permitting on Long Island

Bulkhead work on Long Island commonly involves state, federal and town or village review. Our Permit Navigator lists the agency pages we have verified.

NYS Department of Environmental Conservation

DEC states that tidal wetlands line much of the salt water shore, bays, inlets, canals and estuaries of Long Island. Its Tidal Wetlands Permit Program regulates activities in tidal wetlands and their adjacent areas, which extend up to 300 feet inland from the wetland boundary (up to 150 feet within New York City). DEC lists bulkheads, sea walls, retaining walls, riprap and gabions among regulated activities, and its use guidelines treat in-kind and in-place replacement of existing functional bulkheads differently from new bulkheads in vegetated tidal wetlands. DEC also notes that the U.S. Army Corps of Engineers has jurisdiction and that a Corps permit may be required whether or not DEC requires one.

Other DEC programs may apply. The Protection of Waters program covers excavation or fill in navigable waters below mean high water and some docking facilities. Coastal Erosion Hazard Areas along the Atlantic Ocean and Long Island Sound are administered by DEC or by certified municipalities.

Underwater land

Who owns the land under the water matters. The NYS Office of General Services manages state-owned lands under water and issues licenses, easements and grants for their use. Ask OGS and the town or village whether the work area is state-owned underwater land before design.

Towns and villages

Town and village requirements vary across Nassau and Suffolk counties. The Town of Hempstead's Department of Conservation and Waterways issues Structures in Waterways permits, including bulkhead permits, through an online portal. The Town lists a survey, two sets of construction drawings, a deed, site photographs, a NYSDEC approval letter and contractor insurance among required documents, plus the bog probings noted above. Incorporated villages such as Freeport have their own building departments, and other towns, including Babylon, run their own permit offices. Contact the town or village where the property is located.

Planning a project here

1. Identify the water: canal, open bay, inlet area or Sound shore. Exposure and tide range differ widely.
2. Ask DEC whether the property is within a tidal wetland or adjacent area, and confirm ownership of the underwater land.
3. Have the designer account for soft bay-bottom soils where present. Hempstead requires bog probings for bulkhead applications.
4. Read the bulkhead permit guide, bulkhead replacement and how to hire a marine contractor.

This page is educational and does not determine permit requirements for any property.