The federal government has agreed to dredge Mattituck Inlet this fall — a project 15 years in the making — and to use the dredged material to rebuild the heavily eroded Sound beach to the east of the stone jetties on either side of the inlet.
The work, which calls for removing close to 100,000 cubic yards of material from the inlet, where shoals pose a threat to commercial fishing boats, is to begin in October at a price of $3.4 million, said Congressman Tim Bishop.
Nearby residents and town officials have been calling for the dredging since 1998.
The inlet is a federal waterway and as such the U.S. Army Corps of Engineers is responsible for routine dredging. But the new project comes under Section 111 of the 1968 federal River and Harbor Act, which requires the corps to mitigate erosion caused by its projects.
In this case, the culprit is the stone jetties, which by extending out into the Sound interrupt the natural west to east movement of sand, known as the littoral drift. As a result a large amount of sand has collected against the west side of the west jetty. But with currents starved of sand, the Sound has scoured away the beach to the east.
In agreeing to the dredging, and the price tag that comes with it, under Section 111, the Army Corps is conceding that the jetties cause the downdrift erosion, said Congressman Tim Bishop.
“That is one of the reasons why this was so hard to get,” Mr. Bishop said. “This is the Corps acknowledging that they have an obligation if there is an ongoing need to replenish the beach east of the inlet.”
The dredging work will both widen and deepen the inlet channel to a depth of 11 feet below mean low water. The dredged sand will be placed on the beach in a 20-foot-wide strip of about 4,500 feet long from the eastern jetty.