International Dredging Review

International Dredging Review

The Corps New York District’s beneficial re-use program takes dredged sand from the harbor deepening program and uses it to rebuild habitats. One of these projects is nearing completion in Jamaica Bay. Travelers using the John F. Kennedy Airport can see the bay as they take off or land.

By JoAnne Castagna Ed.D.

Last summer Melissa D. Alvarez a senior project biologist with the Corps of Engineers New York District was inspecting Elder’s Point East a marsh island in Jamaica Bay the Corps of Engineers and other agencies had restored in 2006.

“I saw movement in the water as the tide was draining one of the creeks. I looked closer and saw something I’ve never seen there. There were dozens of juvenile horseshoe crabs swimming within the tidal creek. They were the size of a quarter but this meant so much more. It means that the restored island is now providing successful breeding for horseshoe crabs” said Alvarez.

She continued “Later in the year I also found a nest of diamondback terrapins a New York State protected species. This once again represents the success we’ve had at Elders Point East and will soon have at Elders Point West.”

The partners are now restoring nearby Elders Point Island West using lessons learned in the first restoration.
The two islands form a marsh island complex within the 26-square mile Jamaica Bay Park and Wildlife Refuge that was the country’s first national urban park and one of the Gateway National Recreation Areas.

The refuge is in an urban area that includes portions of Brooklyn Queens and Nassau Counties New York. The area’s shorelines are bordered by heavily-developed lands including John F. Kennedy International Airport the Belt Parkway and several landfills.

The island complex was once a single 132-acre marsh island named Elders Point but years of degradation split the island into separate islands that are now connected by muddy land.

Today a restored Elders East is 49 acres and Elders West is expected to be approximately 34 acres after restoration is completed this summer.

The once-vibrant marsh islands in Jamaica Bay have been disappearing at a rate of 44 acres per year – faster in the last decade. It’s believed that a great deal of this degradation is due to urbanization and that the islands would disappear by 2012 if it is not halted.

According to Alvarez a certified professional wetlands scientist maintaining the health of the marsh islands is critical to the well being of the wildlife and the 20 million people that live and work in this urban region.
“The benefits of the Jamaica Bay marsh island ecosystem vary depending on scale. From a smaller scale perspective the marsh islands are a home for a variety of wildlife including fish and shellfish which are an important food source for birds and help improve water quality by removing things like nitrogen and phosphates” said Alvarez.

She continued “From a larger perspective the marsh islands provide stability and water storage during storm and flood events. The islands also act as filters or natural cleanser to the water as the plants capture and cycle different nutrients and particles out of the water. By restoring Elders Point and other marsh islands we may even protect the more interior islands and hopefully slow their erosion.”

“For the public this means less erosion to personal property more species available for recreational fisheries better water quality and preservation of the Gateway National Recreation Area that is visited by millions of people each year.

“Bottom line- The marsh islands are an irreplaceable natural resource that provide so many benefits to the surrounding region.”

To restore these islands the U.S. Army Corps of Engineers New York District has teamed up with partnering agencies including The National Park Service Natural Resource Conservation Service New York City Department of Environmental Protection Port Authority of New York & New Jersey and the New York State Department of Environmental Conservation.

In 2006 the agencies restored Elders East by pumping 250000 cubic yards of dredged sand onto the island to proper elevations of a marsh island and hand planted native plant species that included saltmarsh cordgrass salt hay and spike grass that were grown from seed collected from Jamaica Bay.

The sand came from the Corps’ beneficial re-use program that takes dredged sand from the New York District’s New York Harbor Program and area waterways and uses it to rebuild habitats. In the past this sand would have been dumped into the ocean so this program is a win-win for the environment and taxpayers.

Last fall the team began work on Elders West. Recently they pumped 240000 cubic yards of beneficially used dredged sand onto the island which is primarily composed of mud and graded the island to the appropriate elevations for a marsh.

One thing the team learned from East is that when sand is placed on the island it will settle differently in various areas based on the composition of the mud. Because of this different amounts of sand will be placed at different areas of West to achieve proper planting elevations.
The team also learned from East that the side slopes of the placed sand need to be more gradual in order to prevent movement and loss of sand. Steeper slopes resulted in continuous erosion.

To build up East the team placed sand by hand around existing plants and placed the newly grown nursery plants in this new sand.

They learned that this was not good for a number of reasons. Besides being time-consuming and expensive the island was very muddy and the new sand was not thick enough for the newly grown nursery plants and existing plants to grow successfully. When they planted the new plants their roots grew deeper than the new sand layer – choking the plant.

On Elders West the team removed three acres of existing vegetation on the island placed enough fresh sand to ensure plant survival then transplanted the plants back into the fresh sand on the island’s new higher elevations.
At Elders East the team learned that relocating existing plants is just as effective as purchasing and planting vegetation grown in a nursery. They also learned that these transplants did better when they are removed from muddy bay bottom and placed in clean sand.

On the higher elevations of the island they’re going to establish high marsh using vegetation collected from surrounding islands in Jamaica Bay and grown at the Cape May Plant Materials Center part of the U.S. Department of Agriculture’s Natural Resource Conservation Service.
On East seeding was successful so the concept will be expanded to a larger scale on West in the hopes of developing a large scale commercial method that can be replicated on future marsh island restorations. This method has the potential to save money and make marsh restoration more efficient.

On West they will transplant more salt grass instead of seedlings and place the transplants further apart. This will save money because this will require fewer plants.
Work on West will be completed by early this summer.
Will the Corps and their partnering agencies return to Jamaica Bay again?

Mark Lulka Project Manager U.S. Army Corps of Engineers New York DistrictHarbor Branch believes restoration will continue “As we obtain additional experience and funding we hope to build a few other marsh islands as the years go by” he said.

Marsh island restoration in Jamaica Bay advances the goals of the Hudson Raritan Estuary Comprehensive Restoration Plan. The primary goal of the plan is to develop a mosaic of habitats that provides maximum ecological and societal benefits to the region.

This plan was developed in partnership with the Corps’ New York District and more than 60 organizations and stakeholders.

Dr. JoAnne Castagna is a technical writer-editor for the U.S. Army Corps of Engineers New York District. She can be reached at She suggests: “To learn more about the Hudson Raritan Estuary Comprehensive Restoration Plan and the Elders Point Restoration projects please visit”