Turtle-blocking seawall coming down
July 7th, 2016
By Sammy Fretwell
COLUMBIA, SC A series of experimental seawalls that had blocked sea turtles from nesting on parts of the South Carolina coast must come down before the end of the month.
The S.C. Department of Health and Environmental Control ordered the walls’ removal after learning about wildlife concerns from the S.C. Department of Natural Resources, according to a letter Friday from DHEC to a Citadel engineering professor involved in the experimental work.
“We will continue to gather additional information to further assess these concerns,’’ the agency’s letter said.
DHEC officials said engineers at The Citadel must remove the walls by July 28. The seawalls, known as wave dissipation devices, are located at Isle of Palms near Charleston and Harbor Island in Beaufort County. They were installed in front of buildings considered most vulnerable to damage from the ocean. They protect four different spots. DHEC took action after two environmental groups threatened to sue the agency because of the walls’ impact on sea turtles during nesting season. Sea turtle volunteers have snapped photographs the past two summers showing turtle tracks leading to the base of wave dissipation devices.
The S.C. Environmental Law Project praised DHEC’s decision Friday. “These walls have resulted in numerous ‘false crawls,’ where the turtles crawl onto the beach but then turn around before laying their eggs once they encounter the walls,’’ the law center said. The non-profit legal group is representing the Sierra Club and the S.C. Wildlife Federation.
Wave dissipation devices, developed through work at The Citadel, are plastic structures pitched as a way to keep the ocean from hitting buildings on eroding beaches without making erosion worse. They contain openings between plastic slats that are supposed to allow seawater to wash through them, which backers said limits beach erosion. But the walls also are touted as safe for wildlife because they can be taken down, unlike concrete and rock seawalls, during sea turtle nesting season. In this case, wave dissipation devices in three spots -- two at Isle of Palms and one at Harbor Island -- have been in place through all or parts of two nesting seasons, DHEC records show.
Loggerhead sea turtles, which are federally protected because of threats to the species, typically nest from May through late summer on South Carolina beaches. If the big reptiles can’t find places to lay eggs, they often will return to sea and sometimes deposit eggs in other places that are unsuitable for nests. Since June 12, 2015, wave dissipation walls have blocked sea turtles from nesting on at least six different occasions, according to a June 22 letter from DHEC director Catherine Heigel to DNR chief Alvin Taylor. Four were at Harbor Island, she said, in asking the wildlife agency to determine how the blockage was affecting the species. Taylor’s agency responded June 27, saying long wave dissipation walls could hurt nesting.
Rep. Mandy Powers Norrell, D-Lancaster, said a key reason the Legislature approved wave dissipation devices was that they were portable and could be taken down. The Legislature voted to allow their use about two years ago as an experiment. New seawalls are otherwise banned in South Carolina because they can speed up erosion when pounded by waves. “These things should not be allowed to stay up during nesting season,’’ said Powers Norrell, who served on a House committee that examined whether to allow wave dissipation devices.
But state. Sen. Chip Campsen, the major proponent of the systems, said Friday he was disappointed with DHEC’s decision. Campsen said without the wave dissipation devices, property owners will use sandbags to protect their investments. “I don’t think it’s a prudent decision,’’ Campsen, R-Charleston, said. “Wherever these devices were, we’ll have sandbags. And they’ll have the same impact on turtles as wave dissipation systems did.’’ Campsen also noted that sea turtles aren’t as likely to nest on highly developed beaches like those protected by the wave dissipation devices. He said DHEC should have waited until two wave dissipation studies were complete before deciding whether the walls should be removed.
Both The Citadel and DHEC are conducting studies to assess how well the experimental seawalls have worked at Harbor Island and Isle of Palms. Some buildings in both places are precariously close to the ocean during storms and periods of high erosion. DHEC expects to finish its report in the fall. The Citadel’s will be done by Aug. 28, according to plans.
Mike Lewis, a resident of Harbor Island for nearly two decades, said wave dissipation systems prevented two houses from being destroyed during last fall’s historic storms and high tides. “Without the wave dissipation system, it would have been even worse,’’ he said of the storm’s impact on Harbor Island, a gated community of more than 450 developed properties near Hunting Island State Park. “They performed exactly as the originators ... had discussed.’’ Lewis also said that while some turtles have been blocked by the devices at Harbor Island, multiple sea turtles have nested successfully this year