Just a few miles off New Jersey’s coast is a series of underwater hills on the ocean floor, made of perfect-quality beach sand tens of thousands of years old.

Once those hills existed above the waterline as beaches, dunes and barrier islands, before rising seas covered them as the last ice age ended.

Now they are home to small, benthic organisms such as clams, worms and other tiny creatures that live in them. The hills attract fish, which feed off the organisms, preferring a contoured ocean bottom to a flat one.

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And the fish attract fishermen.

But the shoals also attract government agencies, which dredge sand for beach-replenishment projects that fight natural erosion and protect billions of dollars in barrier-island real estate.

The value of these ancient sand hills to sea life, fishermen, scientists and beach-building engineers has set up a fight between those who would protect them and those who would mine them. And that battle is expected to intensify as rising sea levels are expected to magnify.

Meanwhile, every beach on New Jersey’s 127-mile coast will soon have been engineered or replenished after 2012’s Hurricane Sandy, with the U.S. Army Corps of Engineers promising to keep replenishing them for another 50 years.

Only two projects are left to do — the Absecon Island project covering Longport through Atlantic City and the Monmouth/Ocean counties project covering Manasquan to Barnegat inlets.

Both have been postponed by lawsuits from homeowners who don’t want large dunes built near their properties, but contracts recently were awarded and the projects are expected to start soon.

Similar projects are happening up and down the East Coast.

All that pumping can’t help but affect ocean life, said Rob Young of the Program for the Study of Developed Coastlines at Western Carolina University.

“In my opinion, we have never really done a good enough job of examining exactly what the long-term impacts are in all of the places we are now borrowing sand to do beach replenishment,” Young said.

He said studies have shown those small, benthic animals that live in the shoals are killed during the pumping process and smothered on the beach.

The small animals are the food for crabs and fish. And when they are lost from pumping, it can take years for them to return to the dredge site, if they do at all, research has shown.

Sometimes the dredge area — also called the borrow zone — fills in with silt-like material from elsewhere on the ocean bottom, and the type of life that ends up there is totally different, Young said.

Fishermen have been concerned about sand mining for years on the shoals, which they call lumps or ridges.

They say some of the best commercial- and sport-fishing areas have been lost or are being lost because of all the dredging.

“We’re objecting to lumps picking, especially those closest to inlets — the ones used the most by the public,” said Kenneth Warchal, vice president of the Jersey Coast Anglers Association, a trustee of the Manas-quan River Marlin and Tuna Club and co-founder of the Ocean Reef Foundation of New Jersey.

“They want them for the same reason we do. They are easier to get to,” Warchal said.

He said various fishing and environmental groups met last year with the state Department of Environmental Protection, which is working with the Army Corps on beach-replenishment projects, to discuss how to minimize damage to fishing grounds and find alternative sources for sand.

Another meeting is supposed to be held soon, he said.

The Army Corps works closely with other government agencies and fishing interests to minimize damage to fisheries, said Keith Watson, project manager for the Army Corps’ New Jersey Storm Damage Reduction Project.

He said shoals are mined only in part, and their contours are left in place, although lower.

“We are committed to being the best stewards we can,” Watson said

But the Army Corps’ mission to protect life and property must be its first priority.

And it’s not like the corps has a lot of choice.

Sand placed on the beach has to be of a similar grain size to what is already there, said Jeffrey Reidenauer, chief of the Marine Minerals Branch of the federal Bureau of Ocean Energy Management.

“Only certain areas of the sea floor have compatible sand,” he said. “Too fine a sand is washed away too quickly, while too coarse a sand makes the beach profile too steep and hazardous.”

BOEM oversees dredging anywhere in federal waters, which off the Atlantic Coast starts at 3 miles out, while the DEP oversees it in state waters up to three miles out.

Compatible beach sand is a finite resource, Reidenauer said.

It is made of eroded rock carried from the mountains of the northeastern states by rivers and streams, according to The New Jersey Sea Grant Consortium, an educational group that advances knowledge and stewardship of the marine environment.

“These sand deposits are then carried up and down the coast by the longshore current to form the beaches that you see,” NJSGC materials say.

West Carolina University’s Young said dredging and beach engineering don’t just threaten life on the shoals. They also diminish life on the beaches and in the intertidal zones that should be teeming with life.

“On beaches that are renewed for decades, it’s just not alive like a beach that has never been nourished,” Young said. “The only animals you see are foraging gulls looking for french fries.”

He’s not opposed to beach replenishment, he said. He just wants more research done before we plow ahead with the plan to keep replenishing beaches up and down the East Coast for the next 50 years.

“We are moving tens of millions of cubic yards of sand in New Jersey and New York alone, impacting huge swaths of ocean bottom, and we do not know what the cumulative impacts of that is,” Young said.

Contact: 609-272-7219 MPpost@pressofac.com Twitter @MichelleBPost Facebook.com/EnvironmentSouthJersey

In my first job after college got paid to read the New York Times and summarize articles for an early online data base. First reporting job was with The Daily Record in Parsippany. I have also worked in nonprofits, and have been with The Press since 1990.

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