Delaware Bay communities get new defenses from rising seas

New project to combine coastal defense with natural measures to help coastal resiliency
Credit: Larry Niles
Looking west toward Delaware Bay over Basket Flats at the mouth of the Maurice River

New Jersey’s efforts to defend its coasts from rising seas will take another step forward under a new plan to build breakwaters and restore marshland at the mouth of the Maurice River in Cumberland County.

A team led by the American Littoral Society has been awarded $4.8 million in federal funds as part of a $12 million project to build some 6,600 feet of breakwaters and rock barriers that will resist storm surges while helping the shoreline to regenerate naturally after being battered by Superstorm Sandy in 2012.

The rock breakwaters are being designed as “hybrid living shorelines” that will include oyster reefs, mussel beds and plantings of marsh grass to defend a peninsula called Basket Flats — an area of coastline that lies between the Delaware Bay and the coastal towns of Bivalve and Shell Pile in Commercial Township on the west side of the river, and Leesburg and Heislerville in Maurice River Township on the east side.

The work, in three phases over the next two to three years, will also build breakwaters at a nearby area of coast called Northwest Reach, and at East Point Lighthouse, a historic building whose peninsula is being eroded by advancing seas. The idea is to combine a traditional approach to hardening the coast with nature-based solutions that allow the shoreline to adapt to the challenges of higher waters and bigger storms that are already coming with climate change. The project will integrate the technique of “living shorelines” — barriers made of natural materials such as plants, sand or rock — with rock-built breakwaters.

Credit: American Littoral Society
This map shows the main elements of the plan to defend the mouth of the Maurice River. It replaces an earlier map that incorrectly showed a feature not covered by the new grant.

The mouth of the Maurice River is one of eight landscapes nationally that were awarded a total of some $37 million for resiliency projects by the National Fish and Wildlife Foundation, which allocates public funds to private environmental groups.

‘A critical project’

“It’s a critical project at a critical time,” said Tim Dillingham, executive director of the New Jersey-based American Littoral Society, an environmental nonprofit. “This is a case study where climate impacts and coastal resiliency, and opportunities for ecological restoration come together.”

He said the project is designed in part to prevent the continued erosion of Basket Flats, which has protected the nearby towns against storm surges from the bay but is less able to do so as seas rise and storms intensify.

By diminishing the wave pressure on the shore, the breakwaters will also help the regeneration of a 200-acre coastal marsh — an important part of the shore’s natural defense against storm surge — which was destroyed by Sandy.

The project also aims to restore beaches that were used for spawning by horseshoe crabs, which underpin the ecology of the Delaware Bay but which have been diminished over the last 30 years by overfishing and bleeding by the biomedical industry.

“We’re going to put back the natural resiliency capacity of the ecological features that have been long lost and combine them with some engineering approaches to protect these towns and everything that depends on them,” Dillingham said.

Credit: American Littoral Society
Basket Flats

The integration of natural solutions with traditional breakwater techniques is an alternative to “hardening” measures such as groins, bulkheads and concrete sea walls that are commonly used, especially on the ocean side of New Jersey, to protect coastal developments but which naturalists say only divert waters, and do nothing to help the shoreline develop its own defenses such as the regeneration of marshes.

Trying to add to the natural system

“This is unique because we are trying to create real protection in a way that will add to the natural system, not to destroy it for the sake of protection,” said Larry Niles of Wildlife Restoration Partnerships, a consultant who is leading the science and planning for the project. “It is unique because all protective structures in a natural environment must be adapted to the place.”

Defending the coastline from encroaching seas should not be a choice between “hardening” or nature-based solutions, Niles said.

“Can we create safe resilient structures that provide real protection but also improve ecological productivity by adding habitat to species like oysters, horseshoe crabs, and mussels for the benefit of the bay’s unique animal communities?” he asked. “Hardening without consideration for the land around it will destroy the livelihoods of the people who depend on natural resources to make a living and deprives all of the benefit of a robust ecosystem like Delaware Bay.”

The new breakwaters will be made of small rocks that will not only be less expensive than concrete hardening techniques but are also designed to absorb rather than repel wave energy, said J. Richard Weggel, a retired civil engineering professor from Drexel University in Philadelphia, who is leading engineering on the project. Smaller rocks will be used because they have small spaces between them that don’t trap horseshoe crabs, unlike the larger boulders that are commonly used for jetties and breakwaters, he said.

Preventing further erosion

“The whole idea of the breakwater is to prevent the further erosion of the wetlands, to maintain an area where Spartina grass will thrive and not be eroded by an incoming wave,” he said

Niles, a former Department of Environmental Protection biologist who has led efforts to protect shorebirds on Delaware Bay beaches for the last 25 years, said the new project is also distinguished by its inclusion of shore communities, whose fishing- and tourism-based economies are threatened by rising seas in an era of climate change.

Ken Whildin, deputy mayor of Maurice Township, said his community wholeheartedly supports the project although it has not been able to help with funding because it can’t spend money on the marsh that belongs, not to the township, but to the DEP.

“This coastal resiliency plan from the Littoral Society is paramount to saving this area,” Whildin said.

The partners aim to start work in early 2021. Although it has yet to receive another $7 million from the DEP, Dillingham said he is confident of receiving it.

Dillingham said he hopes the project will become a template for coastal defense and restoration in New Jersey and across the country.

“We know that New Jersey and the world has to respond and adapt to the impacts of climate that are already built into the atmosphere,” he said. “We don’t want to see the entire coast of NJ simply armored against the threats. The idea of integrating the ecological components is pretty much with an eye to the future.”