Billboard companies that have longed to clear out state-owned trees that stand between their signs and Georgia highway drivers won a big victory Monday, likely felling the last substantial barrier to doing that.

A unanimous state Supreme Court on Monday ruled that a new law and the state’s plan to allow the tree-cutting are constitutional.

Billboard company advocates said the ruling was a victory for their business and the thousands of Georgia workers whose jobs benefit from billboard advertising. Environmentalists were dismayed.

Billboard companies have long been able to cut some trees in front of their signs, but not all. Well established trees with thicker trunks — often meaning they’re tall, and most likely to block billboards – were protected from cutting. A law passed in 2011 changed that, but the new law was suspended when the city of Columbus sued, with support from environmental groups such as Trees Columbus and the Garden Club of Georgia. Monday’s ruling was their answer.

No trees may be cut until lower courts act to apply the Supreme Court ruling, a process that could take several weeks at least.

It’s a turnabout from 1995, when the state Supreme Court said that giving away state trees for nothing in return but billboards was an unconstitutional “gratuity” to the billboard companies. In the years since then, the Legislature has declared that billboards provide a substantial benefit to the traveling public, and the court has accepted that reasoning. Monday’s ruling affirmed that stance, and also said it’s valuable to the state if the companies take down old signs.

In a statement Monday, a billboard industry representative said the companies would be “responsible stewards” and noted that they would have to do certain landscaping after tree-cutting, grinding down stumps and mowing or scattering wood chips. The companies will also have to pay something for the removed trees.

“We look forward to increasing outdoor advertising’s ability to help local communities reach out to the traveling public,” said Conner Poe, executive director of the Outdoor Advertising Association of Georgia. He said more than 10,000 Georgia businesses use billboards.

The jobs argument was important. So was election spending: The AJC reported in 2011, just before the new law’s passage, that in the 2010 election cycle alone, billboard companies, their industry organization and individuals associated with them spent more than $200,000 on Georgia candidates and elected officials.

Monday’s ruling supporting the new law was bitter for the less well funded coalition of environmental groups who have fought for years to reduce billboards and multiply trees.

Mary Lovings, who used to chair the Garden Club of Georgia’s legislative committee, was one of the green-clad ladies who kept the billboard industry at bay through years of legislative hearings.

“Since the late 1920s we’ve been fighting that battle,” Lovings said, noting she was speaking for herself, not the club. “The bottom line is there’s really not anything we can do. Which is a hard cold fact but that’s where we are … I can jump up and down and scream and shout and it wouldn’t do a bit of good.”

Not every tree is on the chopping block. Trees such as approved “beautification” or historic trees are also protected, but the DOT would have to determine that a tree fit those categories.

That will be likely be wrestled with at DOT and in the courts on a case-by-case basis.

The city of Columbus and its private partners have planted trees across the area on I-185 and arterial roads for beautification projects, according to Columbus City Attorney Clifton Fay, and some were just approved verbally.

New rules issued by the DOT say that in the absence of paperwork a DOT official can determine that beautification trees were permitted by DOT “based on the totality of the circumstances.”

Fay acknowledged Monday’s decision was a significant blow.

“But we hope that counties like [ours] will be able to work with GDOT and get a lot of these things declared permitted beautification projects,” he said, “particularly where we spent hundreds of thousands of dollars of taxpayer money and private money on specific beautification projects.”

The law’s opponents could always appeal to the U.S. Supreme Court, but that is unlikely, Fay said. They’re thinking about whether to ask the Georgia court to reconsider the unanimous decision.