COLUMBIA, SC — A tiny state agency that has awarded billions of dollars for highways and bridges in South Carolina should be abolished and its duties taken over by the S.C. Department of Transportation, a leading conservationist said.

Speaking at a briefing for state senators Wednesday, Charleston environmentalist Dana Beach said the state Infrastructure Bank is little more than a “slush fund’’ for legislators, doesn’t work as anticipated and needs tighter controls.

The bank was established in 1997 to operate independent of the DOT. Its mission is to borrow money so major road projects can be built quickly. Boosters say it has helped finance badly needed projects, including a new bridge over the Cooper River in Charleston and early work on the Carolina Bays Parkway near Myrtle Beach.

But the Infrastructure Bank is controlled by a politically appointed seven-member board that has awarded most of the money to three counties: Charleston, Horry and Greenville, records show. Some 60 percent to 70 percent of the funding commitments have gone to those counties, the bank reports.

Since 1997, the Infrastructure Bank has committed about $3 billion for roads and bridges.

“When it was conceived, it actually used that money effectively in some early projects, but it very quickly deteriorated into what is essentially a slush fund for the people who control the money,” Beach told senators.

He urged lawmakers to put the bank under the DOT and to prevent the bank from committing future bonding capacity beyond what the state already has agreed to borrow.

A bill is expected to be introduced that addresses those issues, as well as changes at the DOT that could include more emphasis on fixing existing roads. Conservation groups upset with what they see as destructive and expensive road projects are expected to back the legislation.

“There is no reason on earth we should have a shadow DOT Commission ... making decisions entirely independent of the existing DOT,’’ Beach said.

The Infrastructure Bank’s focus on the coast and Greenville is a sore spot in other parts of the state — including Columbia, where city leaders need money to relocate train tracks on Assembly Street and build a connector to the Columbia Metropolitan Airport.

“The transformation of Assembly Street and relocation of railroad lines that regularly disrupt traffic and commerce is a major metropolitan priority,’’ Columbia Mayor Steve Benjamin said. “Effective leadership at the Infrastructure Bank is key to making it happen as soon as is possible.”

State Sen. John Courson, R-Richland, suggested after Wednesday’s meeting that too much had been spent on Charleston County projects.

“If we put any more money for bridges and highways into Charleston County, it will sink into the Atlantic Ocean,’’ Courson said.

Beach, who heads the S.C. Coastal Conservation League, said the extension of the Mark Clark Expressway in Charleston is a prime example of the Infrastructure Bank’s misguided priorities.

The bank has committed to borrowing more than $500 million for the freeway extension, but many people oppose it and South Carolina has more important road priorities, such as improving traffic-clogged Interstate 26 between Charleston and Columbia, Beach said.

Project opponents say the road, which is not a state priority, will chew up scenic slices of the Lowcountry and open development corridors in environmentally significant areas, such as John’s Island.

Beach said after the meeting that, although he’s not happy with the DOT and favors reforming that agency, putting the Infrastructure Bank under the road agency would provide greater checks and balances on the board’s spending priorities.

Four of the seven board members are appointed by the top leaders in the House and Senate — and those lawmakers have pushed for the Mark Clark extension in Charleston, Beach said, referring to House Speaker Bobby Harrell, R-Charleston, and former Senate pro-tem Glenn McConnell, R-Charleston. Two of the members are Sen. Hugh Leatherman, R-Florence, and Rep. Chip Limehouse, R-Charleston. The governor also has two appointments to the bank board.

Boosters of the Mark Clark extension, which include Harrell and McConnell, have said it is needed to complete a local loop around Charleston that was planned decades ago when Interstate 526 was first envisioned. Supporters say it will help move traffic through the bustling port city.

Senators at Wednesday’s briefing didn’t say much about Beach’s plan to put the Infrastructure Bank under the DOT, and some are likely to oppose such efforts. But Courson said the idea has merit.

Courson, who became Senate pro-tem when McConnell became lieutenant governor last year, has asked new bank board member Joe Taylor to look at moving the Infrastructure Bank into the Department of Transportation, he said after the meeting. Courson recently appointed the former state commerce secretary to the board to replace a McConnell appointment, who represented Charleston.

Lt. Gov. McConnell, a Charleston Republican who formerly held the Senate pro tempore post, said the bank was created because the DOT couldn’t fund “mega” projects quickly. Areas that have gotten bank money have been the most aggressive at seeking the funds, he said. He accused Beach of trying to change the bank’s oversight to kill the expressway project. He opposes putting the bank under the DOT.

“We need to improve our infrastructure and we need to maintain the road system, so destroying the Infrastructure Bank doesn’t take us forward – it takes us backward,’’ McConnell said. “Putting things purely under the DOT is not going to remove politics.’’

Beach’s presentation came as part of the Conservation Voters of South Carolina’s annual meeting with senators to present the group’s agenda for the legislative session. More than half the Senate’s 46 members attended the session.

During the meeting, the Conservation Voters also urged senators to support legislation:

To make it easier and cheaper for homeowners to put solar panels on their homes, to save money on energy bills.

To protect isolated wetlands that don’t receive federal protection.

To study South Carolina’s river basins.