KIAWAH ISLAND -- In the high-stakes battle over the future of Capt. Sam's Spit, state regulators gave the island's developer a green light this week to build an unusual underground wall below the spit's dunes.

The state's approval earned plaudits from the developers, who have vowed to build on the spit in an environmentally sensitive manner. Opponents vowed to appeal. "I can't even understand why they're doing it," said Sidi Limehouse, head of Friends of The Kiawah River. "I do know we're going to fight it to the very end."

Kiawah Development Partners has said it plans to build up to 50 homes on the spit next to Charleston County's two-acre Beachwalker Park. According to permitting documents, the company wants to install the 340-foot-long underground sheet pile wall to protect a future road and utilities.

It's the latest chapter in a saga that features prominent developers who are proud of their environmental stewardship, a congressman who unsuccessfully tried to help them and one of the most beautiful undeveloped beaches in the state.

The developers' plans first came to light last year after Post and Courier Watchdog revealed that U.S. Rep. Henry Brown, R-S.C., introduced a bill to remove the spit from a federal zone designed to protect fragile coastal lands. By removing the property, future homeowners would be eligible for federal flood insurance, making the land more marketable. The bill triggered an outcry, and Brown killed his bill under pressure from constituents.

Kiawah Development Partners vowed to continue their development effort. As part of their plans, they sought a permit to build a 2,513-foot-long sloping revetment along the Kiawah River to prevent what nature has done several times over the centuries -- cut through to the ocean and flush sand toward Seabrook Island's beaches. Erosion already has eaten into the spit near the county park's parking lot.

In a setback to the developers, the state said no to the 2,513-foot revetment but approved a 270-foot-long structure near the county park. Kiawah Development Partners appealed that decision to an administrative court, leading to a trial this summer.

During the trial, Leonard Long, Kiawah Development Partner's executive vice president, testified that the company took out a $50 million mortgage against the property two or three years ago. The company used the money to help fund a new resort on the Caribbean island of St. Kitts. Long testified that without the revetment, the land wouldn't be as marketable.

In an e-mail Friday, Trenholm Walker, an attorney for Kiawah Development Partners, said the $50 million loan had nothing to do with its efforts to secure permits. "If someone has that hunch or is suggesting this, they are wrong."

He added that testimony in the trial showed that the state denied the revetment permit to block residential development on the spit. The agency "used its permitting power for the revetment to deny vested rights of the owner without paying the owner a cent," he said.

A judge is expected to make a decision in that case later this year.

Meanwhile, earlier this year, the company sought a separate permit to plant a 340-foot-long barrier below the dunes. The company said the wall would be dug into high ground away from the water and was needed in the event a storm cut through the spit.

On Tuesday, the state Office of Ocean and Coastal Management granted the permit, saying it was consistent with state regulations. The permitting documents also said that if erosion causes the fence to be exposed, the state could require that it be removed.

Walker said his clients were pleased with the state's decision. They were concerned that the state would block the sheet pile wall for the same reasons it did in the revetment case. He said it's "plain as day" that a below-ground barrier wouldn't cause an erosion problem.

Limehouse, an outspoken Johns Island farmer, said that someday "the river will reach it, and there it is." He said Friends of the Kiawah River is organizing a kayak trip to the spit Sunday morning. "Once you see the place in person, you realize what's at stake."

Reach Tony Bartelme at 937-5554 or tbartelme@postandcourier.com.