Birds vs. beachgoers?

Recent king tides undercut the dunes on Isle of Palms.

Folly Beach needs beach renourishment sand again. The Isle of Palms needs to renourish. Edisto Beach is planning another round. The work has become more frequent and enormously expensive.

Now there’s the worms.

Beach renourishment causes a long-term decline in the abundance of tiny worms in the sand that shorebirds eat, according to a recently released University of California at San Diego study. That could threaten the survival of protected species like red knots and plovers that migrate long distances and need the food to survive the trips.

That spells permitting trouble. Those scurrying birds in the tidewash could drastically curtail large-scale renourishment crucial to swarms of summer beachgoers, the tourism economy and residents of beach communities.

The impact on endangered or threatened species already is enough of an environmental concern that the projects approved must avoid work during sea turtle nesting season. Shorebird concerns have delayed and jeopardized projects, such as the restoration of nearly eroded- to-ruin Folly Beach County Park in 2013.

“Shorebirds tend to congregate at inlets, but they will use the entire length of island shoreline depending on the abundance and distribution of food resources,” said Melissa Bimbi, U.S. Fish and Wildlife Service biologist. “A lot of our developed beaches no longer provide suitable habitat for many species of shorebirds because they are not able to nest during the spring and summer or rest and feed undisturbed during migration and winter.”

Renourishment is getting tougher to implement just as the beach — and its billion-dollar tourism economy value to the state — is booming. The three beach communities in rapidly developing Charleston now contend with overflow summer daytrip crowds and are searching for solutions to traffic management and parking.

This study is the latest in a growing body of research that already has U.S. Fish and Wildlife Service permit opinions calling for renourishment strategies that minimize damage to the species, and for avoiding renourishment altogether in less developed and protected areas.

The permitting process already is a multiyear, time- and staff-consuming effort for local governments and businesses.

The service is one of a handful of agencies that must sign off on a renourishment project if it’s going to be approved. Conservation groups also weigh in. Now the groups really might dig in their heels to stop one or keep it to a minimum, particularly near inlet shorebirds grounds.

“Now that we know there is evidence of problems from renourishment, we will probably be asking more questions about permit applications. We will certainly be much more interested in the details and watching how each project plays out,” said Katie Zimmerman, Coastal Conservation League air, water and public health program director.

She said it’s possible that after review, the league could determine that an individual project is too damaging for species and fight it.

The beaches here are barrier islands, really not any more than big sandbars sifting and sliding through the surf. Sands erode and pile up downstream, continually reshaping even the most stable stretches. The beach that was there yesterday won’t be tomorrow. The beach you rebuild doesn’t stay put.

In recent years, seas have continued to shred them. Folly Beach has lost the upper tier of sand placed during the 2014 renourishment to create dunes. The inlets at Isle of Palms have been recurrent erosion problems, but storms and more frequent and higher king tides — extraordinarily high tides — are stripping dunes across the length of the island, including stretches considered to be accreting, or gaining sand.

In the wake of another round of king tides last week, “We have had some significant debris on our beach that is indicative of damage,” said Linda Tucker, Isle of Palms town administrator. The debris includes wood that appears to have come from dune walkovers, she said.

As of Thursday, 10 emergency orders were in effect to allow sandbags or wave dissipation devices at the Wild Dunes resort on the northeast end of Isle of Palms, according to Jim Beasley, S.C. Department of Health and Environmental Control spokesman. “Sandbags have been employed extensively in this area,” he said.

Also on Thursday, DHEC approved a permit modification that increased from 500,000 to 814,000 cubic yards the amount of sand that can be renourished from a beaching sandbar to shore up those properties, he said.

The expense of keeping a beach is skyrocketing. About a third of Isle of Palms’ 5-mile beach was renourished in 2008 from beaching sandbars, at a cost of $10 million. The new work is the latest of costly touch-up jobs that have been done since in the same stretch.

Folly’s cost climbed 200 percent since the 1990s to $30 million for the 2014 work from sand offshore. There are no estimates yet how much a new round would cost.

Federal legislators incrementally are backing away from the renourishment business, no longer willing to pay the lion’s share of that climbing cost. Beach communities are faced with paying more of the load on their own, and might well be forced to turn to beachgoers for the funds.

Then they have to deal with worms.

Reach Bo Petersen at (843) 937-5744, @bopete on twitter or Bo Petersen Reporting on Facebook.