An urban ‘chain of pearls.’ Land deal struck to protect 650 acres near Congaree River.

A Columbia area family has sold nearly 650 acres to a conservation group as part of a deal to create a large urban nature preserve just west of the Congaree River in Lexington County.

The Open Space Institute purchased the property for $7 million from the Taylor family last week after months of negotiations, the organization said. The non-profit land preservation group plans to resell the property for the same price to the S.C. Department of Natural Resources for expansion of the Congaree Creek Heritage Preserve.

If that happens, the Congaree Creek preserve would encompass more than 1,200 acres, roughly double its existing size. The Congaree Creek site would be bigger than most of the state heritage preserves in South Carolina.

State funding to acquire the land is expected to come from the S.C. Heritage Trust program and the state Conservation Bank.

The existing 630-acre preserve lies between the 12th Street Extension and Charleston Highway in Cayce, just a short distance from downtown Columbia. Congaree Creek, a major stream, runs through the preserve on its way to the Congaree River nearby.

The property being purchased is adjacent to the current preserve and is filled with creeks, high bluffs, swamps, a rare white cedar forest and plant-rich bogs. One bog alone has 14 rare species, said L.L. “Chick’’ Gaddy, who has surveyed plants on the land. The property also has plenty of wildlife, including wood ducks, deer and birds of prey. And it has archaeological significance, in keeping with the historical importance of the existing Congaree Creek site, state officials said.

“It is sort of a chain of pearls in an urban area,’’ Gaddy said of the land.

Taylor family members had been seeking to sell the land for preservation, but development remained a possibility on part of the property if the deal fell through. The sale closed last Thursday, solidifying the agreement that has been under discussion.

Edmund Taylor, whose family traces its roots in Columbia to the American Revolution, said the public should enjoy the property.

“We’re tickled to death there are not going to be houses on it.,’’ Taylor said, noting that DNR archaeologists had been helpful in putting the deal together. “It’s going to be a wonderful resource for Columbia and Lexington County.’’

Ken Prosser, assistant deputy director for wildlife and freshwater fisheries at the DNR, said the land acquisitions should be taken up by the state Joint Bond Review Committee and the State Fiscal Accountability Authority later this summer. Those boards must examine proposed land deals.

“The plan is to make it part of the Congaree Creek Heritage Preserve,’’ Prosser said. “It obviously is of importance to DNR or we would not be pursuing it..’’

Funding details must still be worked out. But the S.C. Conservation Bank, an organization that buys land for protection, would likely provide some of the money, bank board Chairman Mike McShane has said.

Last week’s deal had been questioned by state Treasurer Curtis Loftis, who raised concern about the appraisal for the land and the price the state could pay. He also had questioned whether utilities might need some of the property to extend pipes.

But Loftis said his concerns have been mollified after discussions with those familiar with the transaction.

“We asked a lot of questions, we got tons of good answers back,’’ said Loftis, who lives in Lexington County. “Everybody acted in good faith (and) to my knowledge, we felt comfortable with the transaction. Any of these complex transactions are not exactly how one would do it themselves, but you can understand it.’’

In a statement Tuesday, the Open Space Institute said it looks forward to South Carolina taking control of the land for public use. The expanded preserve would make for a significant public recreational spot and would “give Lexington County one of South Carolina’s largest, most accessible public green spaces,’’ the institute said in a statement Tuesday.