If the state Department of Transportation’s board tries to stop the completion of Interstate 526 from moving forward, it could be on the hook for $117 million, according to Charleston County Council Chairman Teddie Pryor.

He thinks that’s at least one of the reasons the DOT’s commission on Thursday backtracked on an attempt to stop the project.

Projects funded by the S.C. Transportation Infrastructure Bank, such as the $558 million extension of I-526 across Johns and James islands, require local matching funds, Pryor said. But instead of cash, the county was allowed to use the cost of improvements it made to state-owned roads within its borders as the local match for I-526, he said.

If the DOT doesn’t follow through in its role to build the road, it could end up having to pay back the $117 million to Charleston County, Pryor said.

The road improvements used as a match money for the Mark Clark extension were among the items voters approved in a 2004 half-cent sales tax referendum, which included roads, public transportation and green space projects, according to Pryor.

He and other local leaders say it was common knowledge that the referendum included projects that subsequently would be used to leverage money to extend I-526. But some project opponents say that’s not true, and they never would have voted for the referendum if they had known they were helping fuel the plan to build the Mark Clark extension.

County Councilwoman Colleen Condon said she was running for County Council in 2004 when the referendum was being developed, but she didn’t take her seat until 2005. Condon, one of four council members who voted against the I-526 project last year, said she voted for the referendum, but she didn’t know at the time that some projects were being used as a match for I-526.

Robin Welch, founder of the opposition group Nix 526, said she and many other opponents didn’t know that if they voted in favor of the 2004 referendum, they were supporting matching funds for the controversial road. “No opponent would have voted for that,” she said.

According to county officials, the match projects were:

$70 million for widening and intersection improvements to Johnnie Dodds Boulevard in Mount Pleasant.

$18 million for widening and intersection improvements to Harborview Road on James Island.

$7.5 million to upgrade the intersection of the Glenn McConnell Parkway and I-526 in West Ashley.

$15 million for widening Maybank Highway on Johns Island.

$6.5 million to upgrade the intersection of Folly Road and the James Island connector, a project that subsequently was dropped from the list.

State Rep. Leon Stavrinakis, D-Charleston, who was on County Council in 2004, said the county intentionally included those projects in the referendum to provide matching funds for I-526.

I-526 wasn’t specifically mentioned on the ballot, which simply included the list of projects, Stavrinakis said. But county and other local leaders publicly discussed the I-526 match, he said. “Everybody knew.”

County Council Vice Chairman Elliott Summey said he also thinks everybody knew they were voting for matching projects for I-526. “It was a constant part of the discussion,” Summey said.

County Councilman Dickie Schweers said it doesn’t matter if people talked about I-526. It wasn’t mentioned on the referendum ballot. “Show me. Show me where it is,” he said. “It’s not.”

Meanwhile, DOT and Charleston County staff members will begin meeting to finalize a new contract on the project, and DOT commissioners likely will vote on the contract at a December meeting.