New promise for the preservation of Cumberland wetlands

Credit: (asturnut on Flickr; CC BY-NC 2.0)
Mauritius river

Bivalve’s historic oyster fleet, located at the mouth of the Mauritius River in Cumberland County, takes another step towards better protection against the onslaught of rising sea levels and erosion of marshes.

Last year, a team led by the American Littoral Society, based in the Highlands, received $ 4.8 million in federal funds to plan a $ 12 million project that would see the construction of a rock cover and breakwaters, as well as oyster reefs, mussel beds, and other natural barriers, in areas around the mouth of Mauritius which have been severely eroded in recent years.

This left team members on the hunt for an additional $ 7 million, which they hoped to get through a state game. This month, they learned they were halfway there: the state, using the recently passed budget, has earmarked $ 3.2 million in matching funds for the project. The award will launch the tender and contract award, as well as the first phase of construction.

“This is obviously a huge step forward,” said Tim Dillingham, executive director of the Littoral Society. “We have all the required state and federal permits in place, and now we have the funds to get us started.”

The project will address in three phases several endangered areas at the mouth of the river. The first priority is the critical erosion of Basket Flats, a salt marsh peninsula that stretches from the western shore of the mouth and protects the oyster docks of Bivalve and Matts Landing from the waves and currents of the open bay. Since 1985, Basket Flats have been winnowed for over a quarter of a mile, eliminating virtually an entire stretch – or bend – of the river.

The Basket Flats erasure also caused an increase in the amount and frequency of wave energy hitting Northwest Reach, on the opposite shore, resulting in a half-mile wide band of open water where There were once healthy marshy wetlands.

Initial phases

Basket Flats will be addressed in the early stages of the project, which Dillingham plans to launch early next year.

A rock covering approximately 8 feet high and 400 feet long will be constructed at the head of the Basket Flats Peninsula, curving to match the westward curve of the shore. On the bay side, nine 200-foot-long rock breakwaters will guard the open water just offshore and will be fortified by sub and intertidal oyster reefs. Along the shore, schools of mussels and Alterniflora spartine grass will be planted which can help the swamp grow faster.

The final phase involves Northwest Reach, where 18 breakwaters approximately the same length as those in Basket Flats will be constructed to reduce the erosive currents of the open bay. This area will also include oyster reefs and riparian areas planted with mussel beds and Alterniflora spartine.

In addition to stopping work in the spring and early summer for the annual shorebird migration and horseshoe crab spawning, work will continue until early 2023, when Dillingham estimates that the early phases of the project will be completed.

Credit: (mtstradling from Flickr; CC BY-NC 2.0)
Mauritius river near Bivalve

In addition to the $ 12 million in restoration work planned for Basket Flats and Northwest Reach, the Littoral Society hopes additional funds can be found to help shore up the eastern mouth of the rapidly endangered river, where the lighthouse Historic East Point, the second oldest light in New Jersey, sits dangerously close to the water’s edge.

For years, the state embarked on shoreline hardening projects at East Point that failed in terms of slowing the erosion of the narrow beach that stands between the lighthouse and the bay. Here too, a combination of breakwaters, rock coverings and living shorelines could be built to better protect the lighthouse.

“Much like Bivalve, East Point is an irreplaceable historical resource, and it is vulnerable and worn out,” Dillingham told NJ Spotlight News earlier this year. ” Something has to be done. “

The dredging project also seen as an aid

Shoreline replenishment is also underway with material dredged from the Mauritius River Canal, thanks to a separate project from the State Divisions of Fish & Wildlife and Coastal Engineering, and the Army Corps of Engineers, which is part of President Joe Biden’s budget for fiscal year 2022. year.

Although entirely separate from the work of the Littoral Society, the $ 4 million dredging project would provide another substantial boost to the protection of a waterway and marine ecosystem that has been historically neglected by governments. state and federal.

The Mauritius River channel has not been dredged since the 1990s, and shoals have become a danger there, especially for the larger boats that make up the bivalve oyster fleet. In its entirety, the project aims to create a channel 7 feet deep (from medium low water) and 150 feet wide across the mouth of the river. (Additional survey data from the area will be processed by the end of this month, when project partners will meet with local stakeholders to determine and define the most optimal dredging locations.)

The difference between this dredging effort and those of the past is the philosophy of the Corps and the New Jersey Department of Environmental Protection on the use of material removed from the seabed. In the past, channel sediments – which in the inner bay waters of southern New Jersey tend to be a mixture of fine-grained material with sand – were considered unusable and transported to facilities for Contained disposal located off-site.

New philosophy in play

In recent years, however, the State and Corps have experimented with using these materials to redistribute them to eroded shores and marshes adjacent to dredging projects. At test sites in neighboring Cape May County, the Corps, State, and local partner The Wetlands Institute have successfully created marshes and mudflats through “sediment enhancement,” a technique that uses a nozzle. spray to gradually distribute thin layers of dredged material. to elevate land while minimizing impacts on existing vegetation.

“The ultimate goal is not for some of these projects to be big construction projects, but nurturing endeavors, like fertilizing your garden,” said Monica Chasten, project manager in the Body Operations Division who is leading the work. of the agency at both Cape May County and Mauritius River Test Sites. “So maybe we could go through and pulverize some fine-grained material, throwing it back where it came from.”

Credit: (mtstradling from Flickr; CC BY-NC 2.0)
Mauritius river marshes

Once the initial dredging is complete, Chasten said, the hope is that the Corps will return regularly to perform smaller-scale maintenance dredging as well as to improve the sediment – a long-term effort that would both maintain the deep channel and to provide a consistent recharge of critical elements. shorelines like the northwestern section and other vulnerable swampy areas nearby.

At this point, the dredging must overcome a series of federal regulatory hurdles, so it will not begin until after the Littoral Society project. But Chasten and Dillingham agree that the combined efforts point to a new era for the once-forgotten Bayshore, especially the Mauritius River and its oyster fleet at Bivalve.

“Everything we learn about any of these projects,” said Chasten, “we all share as a community.”

Dillingham agreed. “We have to find better ways to adapt,” he said. “And I think these projects, because they’re on a larger scale, will give us a chance to prove that it can be done, and that it can be done collaboratively.”

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