It looks likely that eight super-exclusive, very pricey homes — lots alone run between $3.5 million and $5.5 million — will be built on Sea Island on a sliver of beach and marsh knows as “the spit.”

But will the homes survive a rising Atlantic Ocean and the erosion that has already claimed alarming chunks of beach in just the past 10 years?

The Sea Island Co. wants to build another groin — a wall in the ocean that protects a beach — and has approval from the state. But a lawsuit by environmental groups opposing the groin will be heard by an administrative law judge May 9. A federal agency has already recommended that the groin not be built, citing “adverse impacts to the natural environment and protected species.”

It could take five years for the regulatory and legal issues to be resolved. Meanwhile, the Sea Island Co. is expected to get Glynn County’s approval Thursday to begin selling the lots.

“The fix is in on the development,” Megan Desrosiers, the executive director of the coastal nonprofit One Hundred Miles, said Wednesday. “The County Commission and the island have some sort of understanding that development there is OK. The battleground right now is over the groin.”

No end is in sight to the two-year quest by the company that runs the island, a favorite destination for well-heeled Atlantans, and touts the spit as “one of the most exclusive real estate opportunities ever offered at Sea Island.”

That’s saying something: Old World mansions and pricey condos sit alongside The Cloister hotel, where a one-bedroom suite this weekend runs $1,000 a night. Ever since Sea Island emerged from bankruptcy in 2010, developers have eyed the spit, an achingly beautiful, mile-long strip of sand, marsh and pine scrub favored by horseback riders, sea turtles and shorebirds.

The company is marketing eight home sites on 8-plus acres — the development’s footprint grew recently by 1.3 acres — just below the Cloister and sandwiched between the ocean and the Black Banks River. The remaining 80 acres were placed into a conservation easement.

Scott Steilen, the president of the Sea Island Co., said via email Wednesday that the construction won’t harm the environment. He also expects Glynn County commissioners to sign off Thursday on the updated construction plat for The Reserve at Sea Island.

“Our plan complies with all county requirements,” Steilen said. “This is a routine process that is not dissimilar to other developments in the county. … We look forward to proceeding with the development of eight lots, which will be bounded to the south by land that will never be developed.”

Glynn planning officials have given their blessing to the Reserve’s new bridge, road, water and sewer lines. The commissioners’ vote is largely perfunctory. The lots could be up for sale next week, said David Hainley, the county’s community development director.

Protecting those homes from the sea's surge, though, is another matter. Between 2003 and 2013, the beach alongside the planned development shrank by 108 feet — a rate more than double the mean erosion rate, according to a Georgia Southern University geologist. The beach practically disappears at high tide. The spit is the only spot on Sea Island ineligible for federal flood insurance.

Sea Island wants to build a 350-foot-long rock groin, a quarter-mile below an existing Sea Island jetty, perpendicular to the spit to keep sand in place. A 120-foot wall parallel to the beach would also be constructed. A sand dune, with up to 120,000 cubic yards of sand, would be added to further buffer the homes from tides and waves.

"The groin is a bad idea because it would cause additional erosion down-drift of the groin," said Steve Caley, the legal director for GreenLaw, an Atlanta-based nonprofit. "Typically, groins are approved to protect existing homes. But this is an undeveloped piece of land that Sea Island wants to develop in order to make a bunch of money."

The state’s Shore Protection Committee approved the project in December. But GreenLaw, One Hundred Miles and other environmental groups sued to overturn the decision. An administrative law judge will hear the case next month in Brunswick. Hainley, the county planner, said the case could drag through the courts for five or six years. (Caley estimates three years.)

Federal agencies are reviewing the groin permit and, depending on their decisions, could prompt further legal challenges. The U.S. Fish and Wildlife Service reported in November that “another groin will have negative impacts to sea turtles and have possible adverse impacts to the Sea Island spit which is utilized habitat for federally listed shorebirds and sea turtles.”

It recommended denying the groin permit. The U.S. Army Corps of Engineers is investigating biological and endangered species impacts, as well as possible sand-shifting effects on neighboring St. Simons Island.

“The project will enhance wildlife habitat by creating beach area where none currently exists, and by protecting the shoreline from storm damage,” Steilen said. “None of the species listed as endangered or threatened by the federal government are likely to be adversely affected.”