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Governments Plan for Development of Land Vulnerable to Rising Sea Level: New Jersey

Michael Craghan et al. 2010. "New Jersey". In The Likelihood of Shore Protection along the Atlantic Coast of the United States. Edited by James G. Titus and Daniel Hudgens. Report to the U.S. Environmental Protection Agency.

The summary is on this page. You can also download a printer quality version of this New Jersey sea level rise planning study Craghan et al. (pdf 3.3 MB, 127 pp).


Sea level is rising 12-16 inches per century (3-4 millimeters per year) along the coast of New Jersey. Ocean beaches are eroding, prompting beach nourishment projects along most of the developed New Jersey Shore. Along the shores of Delaware Bay, beaches and marshes are eroding, and aging dikes are increasingly vulnerable. Along the bay side of Long Beach Island, high tides now flood some streets that were dry when the roads were originally paved. All of these effects could become more widespread if rising global temperatures cause the rate of sea level rise to accelerate The Intergovernmental Panel on Climate Change, for example, estimates that by the end of the next century, sea level is likely to be rising 0 to 3 inches per decade more rapidly than today (excluding the possible impacts of increased ice discharges from the Greenland and Antarctic ice sheets).

The state has a policy of nourishing ocean shores. But for most coastal areas, including the bay sides of most barrier islands, there is no explicit plan for the fate of most low-lying coastal lands as sea level rises. Environmental planners do not know whether to assume that the coastal wetlands will be lost or simply migrate inland. Those who plan coastal infrastructure do not know whether to assume that a given area will be submerged by rising waters or protected from the sea. And even in developed areas that will presumably be protected, public works departments do not know whether to assume that the land surfaces will gradually be elevated or that the area will be protected with a dike.

This report develops maps that distinguish shores that are likely to be protected from the sea from those areas that are likely to be submerged, assuming current coastal policies, development trends, and shore protection practices. Our purpose is primarily to promote the dialogue necessary to decide where people will yield the right of way to the inland migration of wetlands and beaches, and where we will hold back the sea. A key step in evaluating whether new policies are needed is to evaluate what would happen under current policies. The maps in this report represent neither a recommendation nor an unconditional forecast of what will happen, but simply the likelihood that shores would be protected if current trends continue.

We obtained the land use and planning data for the state's coastal zone, and consulted with planners representing the 11 coastal counties along the Delaware River, Delaware Bay, Atlantic Ocean, and Raritan Bay, and the Meadowlands Commission on how to best interpret the data given existing statutes, regulations, and policies. We also conferred briefly with planners from 3 of the coastal counties in Northern New Jersey, and Monmouth County obtained input from boroughs and townships. The result is a statewide series of maps that uses existing data, filtered through the county governments who coordinate land use planning activities.

By "shore protection" we mean activities that prevent dry land from converting to either wetland or water. Activities that protect coastal wetlands from eroding or being submerged were outside the scope of this study. This study does not analyze the timing of possible shore protection; it simply examines whether land would be protected once it became threatened. Nor do we analyze whether shore protection is likely to be a transitional response or sustained indefinitely.

The sea level rise planning maps divide the dry land close to sea level into four categories of shore protection:
---shore protection almost certain (brown);
---shore protection likely (red);
---shore protection unlikely (blue); and
---no shore protection, i.e., protection is prohibited by existing policies (light green).

For reasons related to data quality, our study area includes lands within about 17-18 feet (about 5 meters) above the tides. (We did not project the fates of secured federal installations but depicted them in red so that they stand out.)

One can also view these maps as representing three shore protection scenarios. For example, in an "enhanced wetland migration" scenario, only the areas depicted in brown would be protected; but in an "enhanced shore protection" scenario, only the areas depicted in light green would be submerged. Thus the prospects for shore protection are best understood in the areas shown in brown and light green; those shown in red and blue are most amenable to coastal planning. "Expected shore protection" is an intermediate scenario in which the areas depicted in brown and red are protected, and those shown in blue and light green are submerged.


The summary map shows our assessment of the likelihood of shore protection for the coastal zone of New Jersey, and adjacent areas of New York, Pennsylvania, and Delaware. Table 1 quantifies the area of land within approximately 3 feet (1 meter) above the tides for each of the shore protection categories by county. Table 2 quantifies the length of New Jersey's shoreline along the Atlantic Ocean, Delaware Estuary, and back barrier bays by likelihood of shore protection.

New Jersey has a well-established policy in favor of shore protection along the developed ocean shores. As a result, shore protection is almost certain along 80 percent of the state's 137-mile (220-km) ocean coast. The only major exceptions are the 11-mile (17-km) Island Beach State Park-where shore protection is likely-and the 9-mile (14-km) Forsythe National Wildlife Refuge, which extends from the southern portion of Long Beach Island to the northern portion of Brigantine Island.

Along the mainland shores behind the barrier islands, by contrast, wetlands are likely to have room to migrate inland in most areas. Approximately 85 percent (30 square miles) of the dry land within 3 feet above the tides is likely or certain to be protected; but 23 square miles (61 square kilometers) of nontidal wetlands also lie within 3 feet above the tides. Planners generally expect these lands to remain off-limits to development, creating the potential for conversion from nontidal to tidal wetlands. Thus, tidal wetlands would continue to be found in most areas that have them today. Nevertheless, because the area for possible wetland migration is a small fraction of the more than 2,000 square miles (nearly 5,500 square kilometers) of tidal wetlands currently found along the Atlantic Coast, this area would lose 85-90 percent of the tidal wetlands if wetlands prove to be unable to keep pace with rising sea level, regardless of policies regarding wetland migration.

Along Raritan Bay and its tributaries, by contrast, the prospects for tidal wetlands are more sensitive to governmental policies. The area currently has 23 square miles of tidal wetlands, but only 1.4 square miles of nontidal wetlands. Because 95 percent of the land within 3 feet above the tides is likely to be protected, only 0.5 to 1.9 square miles of land would be available for new wetland creation. Nevertheless, the Meadowlands includes 6.2 miles (16 square kilometers) of land (shore protection likely) that might be allowed to flood if wetland protection became a priority.

The Delaware Estuary has a long history of shore protection. With the large tide range, it had extensive marshes that could be "reclaimed" as agricultural lands by constructing dikes and simple drainage systems. Several dikes were constructed along the Delaware River when New Jersey was still a Dutch colony. By 1866, 20,000 acres of marshes had been reclaimed from the New Jersey side of Delaware Bay and converted to farmland, mostly in Salem and Cumberland counties. Since the turn of the 20th century, however, these land reclamation efforts have been reversed, and formerly diked lands have been converted to marsh. (Dikes still protect some populated areas, however, such as the "Gibbstown Levee" in Gloucester County.)

The momentum of these environmental restoration efforts has extended inland: The state plan of New Jersey discourages development along most of the undeveloped areas south of the Delaware Memorial Bridge. Above the bridge, however, most of the shore is developed and shores are likely to be protected. Development has been removed from all but a few bayfront communities in Cumberland County as part of an environmental restoration program. Most of the tidal wetlands along the bay shore of Cape May County transition to nontidal wetlands, generally within wildlife management areas. Thus, shore protection is likely or certain along 10-15 percent of New Jersey's 104-mile (169-km) Delaware Bay shore, but more than two thirds of its Delaware River shore.


1. The prospects for shore protection appear to be largely established along 86 percent of the 137-mile Atlantic Ocean coast.
---High property values and dense development make shore protection almost certain along 108 miles (175 km) of shore.
---Conservation policies preclude shore protection along approximately 10 miles of shore owned by the U.S. Fish and Wildlife Service.

2. Shore protection is still uncertain along about 14 percent of the Atlantic Coast.
---Cape May County includes 6 miles of military lands and lightly developed barrier beaches where shore protection is likely but not certain.
---Continued shore protection is likely-but not certain-at Island Beach State Park.
---Wide beaches account for about 2 miles of shoreline. Although shore protection is unlikely, the land behind beaches is almost certain to be protected if the beaches erode.

3. Along the barrier bays of New Jersey, most dry land is likely or certain to be developed, but nontidal wetlands may provide an opportunity for the landward migration of tidal marshes.
---Of the 37 square miles of dry land within 3 feet above the tides along the Atlantic Coast of New Jersey, 30 square miles are likely or certain to be protected.
---Approximately 2.1 square miles are within conservation areas, and another 2.9 square miles are in areas where development is unlikely. Thus, the area of dry land that is likely to be available for wetland migration is small compared with the 202 square miles of tidal wetlands.
---Approximately 60 square miles of nontidal wetlands, however, may also be available for the creation of new tidal wetlands. (The extent to which land that is dry today might convert to nontidal wetlands as sea level rises is outside the scope of this report.)

4. Along the Delaware Estuary below the Walt Whitman Bridge, the prospects for shore protection are less certain than along the ocean. These lands include approximately 16.3 square miles of dry land within about 3 feet (1 meter) above the tides.
---Only 36 percent of the dry land within 1 meter above the tides along the Delaware estuary in Cape May, Cumberland, Salem, and Gloucester Counties along the Delaware shore is developed enough for planners to view shore protection as almost certain, and 15 percent of the land is within conservation areas.
---Shore protection is likely on about 17 percent of the dry land within about 3 feet (1 meter) above the tides; but it may not be too late to design land use plans that could accommodate both development and wetland migration.
---In the other 9.7 square miles, development and shore protection seem unlikely today; but land owners may choose to protect these lands in the future.

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Governments Plan for Development of Most Land Vulnerable to Rising Sea (PDF, 7 pp., 1.3 MB) was originally published in Environmental Research Letters , Issue 3, Volume 4 (2009).

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