Dredged bay mud and sand, once as welcome to communities as a trash dump, may be key to saving Delaware Bay beaches and wetlands from erosion and sea-level rise.
This is one concept researchers, advocates and officials are considering as they move ahead with aggressive and creative plans for restoring parts of Cumberland County’s bayshore while ensuring communities most at risk from sea-level rise can better handle flooding and storms.
Ideas for helping the bayshore have long floated around, but recovery from Hurricane Sandy — and the increased federal and philanthropic dollars flowing into New Jersey — has effectively put a spotlight on numerous projects and all but guarantees at least a few will move forward.
“These are projects that protect the natural habitat, but they also provide for natural resilience,” said Tim Dillingham, executive director of the American Littoral Society, which is leading multiple projects along with The Nature Conservancy.
In the wake of the storm, officials and residents from Commercial, Maurice River and Downe townships are working on a list of projects, ranging from educating local officials to building a system of dikes and levies.
Buried within the projects are ideas to use dredged mud and sand, long thrown away in spoils piles as worthless, to restore badly degraded beaches and salt marshes while, in effect, re-creating critical wildlife habitat and recreation spots and improving boat access.
Cumberland County — which could lose 10 percent of its entire land acreage by 2100 due to sea-level rise, according to a report by Climate Central — could become a state leader in finding ways to use nature to fortify its eroding shorelines.
“The bayshore is the perfect pilot project,” said Meghan Wren, executive director of the Bayshore Center at Bivalve. “It’s got small enough numbers for dealing with sea-level rise and future storm surges that we can test things out and figure out what Atlantic City or Miami are going to do.”
Residents, officials and environmental advocates for years all have wanted the same thing without realizing it, said Larry Niles, a wildlife expert and former head of the state Division of Endangered and Non-Game Species. Restored beaches provide recreation and attract tourism, he said. But the beaches also provide critical habitat in the spring for horseshoe crabs to spawn, providing food for migratory shorebirds that use the Delaware Bay as a rest stop on their way to Arctic breeding grounds.
Additionally, Niles said, watermen trying to navigate key tidal creeks and rivers to access fishing grounds and shellfish beds long have struggled with mud shoals. But the problem with dredging those waterways hasn’t just been funding. There also hasn’t been any place to put the spoils.
Dredged sand from these waterways can be used to restore the beaches. Silt and mud, because of the fine grain size, cannot.
Instead of putting the muck into piles, isolated from the environment and lost to the marshes forever, researchers want to spray the fine silt in a thin layer on the marshes to restore degraded wetlands and even build them up so they can survive higher waters.
Other states, including Delaware, Louisiana and New York, have experimented with spraying the muck in a thin layer over degraded salt marshes in an effort to restore the wetlands.
“It’s offsetting the lack of natural sediment in the system and helping the wetlands respond and keep ahead of sea level rise,” Dillingham said. “We know that the technique has had great success in marsh restoration in other areas, and we think it’s a good, needed tool to bring into play in New Jersey.”
Cumberland County has several areas that could be used as experiment sites, but those chosen will depend on dredging projects, Niles said.
One site of interest is the mouth of the Maurice River, where wetlands have been erased by erosion, and the navigation channel to a critically important commercial fishing fleet and shipyard area is in danger of filling in. A project on the long-term planning group’s list would, effectively, rebuild the entire mouth of the river.
The project, which includes multiple phases, would use shellfish reefs to reduce wave energy, living shorelines to stabilize marsh banks and dredged sediment to rebuild the marsh, said Ben Stowman, the chairman of Maurice River Township’s land use planning board and a member of a multi-jurisdictional recovery group along Cumberland County’s bayshore.
“We are in full agreement, our bayshore group, that we are willing to take on the beneficial use of the dredged material, whether from the Maurice River itself or from the larger Delaware Bay river dredging projects,” Stowman said.
Currently, the conceptual project is pegged to cost about $50 million, and funding from various grants and federal agencies is not yet in place. Stowman said the Department of Environmental Protection still has to sign off on a feasibility study. Once that study is approved, the project would be at least several years away from construction, he said.
No formal plans have been submitted to the DEP, agency spokesman Larry Hajna said.
“The idea has been discussed. It has potential, but it needs a lot more evaluation, and we need to make sure it has no adverse environmental impacts, but it’s all very early,” Hajna said. “This has not been done in New Jersey in the past, but it has been done in other states.”
The projects in Cumberland, however, could be the test sites for how projects could be done elsewhere in New Jersey, Niles said.
“What we’re doing overall is we’re proposing these projects with a real scientific effort to document the impact so we can clearly state what the problems are and if they can be fixed,” Niles said.
Contact Sarah Watson:
@acpresssarah on Twitter