Entire East Hampton Coast at Extreme or High Risk

What will happen in the days to come, and in future decades, along East Hampton’s 114 miles of coastline as a result of expected sea level rise and possible storms? This question, and what might be done to avoid worst-case scenarios, is at the core of an attempt to develop a coastal assessment resiliency plan.

A committee appointed by the East Hampton Town Board early this year has begun examining potential impacts on East Hampton’s coast, using different projections as to the degree of sea level rise and the strength of storms. Gardiner’s Island has not been included.

On Tuesday, at the first public presentation on the effort, which participants refer to by the acronym CARP, Jeremy Samuelson, the head of the committee, described the formidable task with other questions. “How many acres are we going to lose? What is the shape of our community going to be? Where will the impacts be?”

Dr. Sam Merrill, a conservation biologist with GEI Consultants, a firm of engineers and scientists based in Portland, Me., who was hired to help draft a plan, shared the company’s analysis of what the town might face. Models taking into account the “combined threats of sea level rise and storm surge” show that many acres could be lost to rising waters, with significant economic impact.

After assessing just what could occur, Mr. Samuelson said, the next step is to discuss what could be done. Again, he asked questions: “Are we buying property, raising structures, incentivizing or dis-incentivizing development in certain areas?” Involving the community in discussion and approval of any plan will be key, he said. “We’ve got to change what we are doing. Literally, the shape of our town is going to change. We’re better off having a plan.”

Mr. Merrill said his company has worked with waterfront communities throughout the United States and overseas to create such plans. “Resiliency,” he said, is the ability to “bounce back after change or adversity,” as well as the “capacity to prepare for, respond to, and recover from difficult conditions.” The process is “about creating options for ourselves,” Mr. Merrill said.

According to National Atmospheric and Oceanic Administration data collected at Montauk, mean sea level rise here has been approximately 3.2 millimeters a year, or just over a foot, over 100 years.

The “patterns of vulnerability,” Mr. Merrill said, differ along the south-facing oceanfront of East Hampton and the coastline on the bayfront and depend on whether one looks at sea level rise or storm surges, or both, and under best and worst-case scenarios.

Contrary to what many might assume, he said, the projections show more future impacts along the bayfront than the ocean.

The consultants based their analysis on projections adopted by the New York State Department of Environmental Conservation for medium or high sea level rise. Using the higher projection by the state, sea level could rise 21/2 feet by 2050 and 4.8 feet by 2080. Under a more conservative projection, sea level might be expected to rise 1.3 feet by 2050 and 2.5 feet by 2080.

What that could mean for East Hampton was depicted on a series of maps prepared by GEI. A map showing the state Department of State assessment of coastal areas at risk is based on Federal Emergency Management Agency’s designations. Areas at “extreme” and “high” risk include those that are already regularly flooded and would be affected by three feet of sea level rise and-or by a so-called 100-year storm. These areas include virtually the entire shore perimeter of the town. Areas at moderate risk are those that would be affected by a Category 3 hurricane, or by 3 hurrican, or by a 500-year storm.

Using separate modeling strategy, the consultants looked at the assessed value of the real estate at risk. Their economic assessment does not include impacts from the destruction of infrastructure, like utility stations, or the destruction of natural resources, or impacts related to a loss of tourism and the like.

For example, the estimated market value of real estate at risk along the Gardiner’s Bay shoreline in the Springs area was tallied at $538 million; along the ocean shore in East Hampton Village the value of at-risk real estate was set at $1.5 billion, and on Napeague it was $2.1 billion.

The consultants also prepared maps showing where East Hampton’s future coastline could be, based on the various projections of the degree of future sea level rise. Should sea level rise by 4.8 feet, 598 acres around Northwest Harbor, valued at $88.1 million, could be lost by 2080. Under the most conservative estimate, 492 acres in that area, valued at $64.6 million, would be under water by 2050. Along the south end of Lake Montauk, sea level rise could wash out 149 acres, valued at $22.9 million, by 2050, or, inundate 192 acres valued at $49.2 by 2080, according to the most extreme estimate.

There will be “a lot more inundation of acres on the bay side” of the town as a result of sea level rise, Mr. Merrill said, with a higher cost in many cases. But the pattern is reversed when looking at the effects of storm surge, with Napeague and East Hampton Village facing the most exposure and potential loss of value, both in the short term and over the next 50 or 60 years.

According to the consultants’ estimates, total damages from all storms that could occur through 2080, including a 100-year storm (defined as a storm with a 1-percent chance of occurring in a given year), and with 16 inches of sea level rise, could reach $263 million in a south-facing Wainscott and East Hampton Village zone, $806 million on Napeague, $69 million along Accabonac Harbor, and $64 million in downtown Montauk.

The study also looked at public facilities, including the Montauk Airport, train station, and electrical substation in Montauk, and the town commercial dock in East Hampton, and concluded that most are already vulnerable to storm surge. If some action is not taken to adapt to expected sea level rise, according the consultants, “they can be expected to be underwater at high tide every day” in the future.

The starting points for the study are “ballpark estimates, and there are assumptions baked in, but it does give a framework for discussion,” Mr. Merrill said, enabling the community to look at “where might we want to take some action, and what are our greatest concerns?”

Scientists and policymakers are constantly revising estimates of sea level rise, Mr. Merrill acknowledged, and the estimates used in the modeling for East Hampton could be revised as the process goes along, but “at some point you have to say, let’s start” a conversation based on a particular set of projections. “If you wait, the damage will only go up,” he said.

As the process continues, Mr. Merrill said, the discussion will include whether to take community-wide action, such as elevating roads, rail lines, and other infrastructure, augmenting or creating barriers along shorelines, or protecting open space as “living shorelines.” Individualized action, parcel-by-parcel, such as elevating buildings and flood-proofing, also have to be considered, he said, as well as town policies regarding, for instance, voluntary buyout programs for shorefront properties, providing incentives designed to get property owners to move buildings back from the shore, revising the zoning or building codes, or a transfer of development rights program.

Tuesday’s meeting was the first of a series of public sessions, Mr. Samuelson said. The presentation made at this week’s meeting will be posted on the town’s website.

Correction: This story has been updated from the original to correct an error regarding the possible monetary damages storms could cause in various shoreline areas. The estimates include potential damages from all storms that might occur through 2080, assuming there is 16 inches of sea level rise, and not just the damages from a 100-year storm.