A federal agency has officially given the Chicago Rockford International Airport the greenlight to restart construction on a $50 million expansion that is expected to bring new business and jobs to the city. Construction could resume as soon as Thursday.

But a conservation group is moving quickly to block the bulldozers. Activists want to put off a project they say threatens prized prairie habitat and is a home of the Rusty Patched Bumble Bee.

The fight over an 8,000-year-old remnant prairie in the middle of one of the country’s largest cargo airports has unfolded over the past two years and put the spotlight on Illinois’ dwindling prairie ecosystems.

Relations have soured over that time between airport officials and conservationists, who for decades shared a commitment to maintaining and promoting the prairie, known as the Bell Bowl. Now the two sides are barely on speaking terms.

On Friday, the Federal Aviation Administration approved a plan that would let the airport build a road through the middle of the highest quality section of the prairie. The plan preserves six acres of habitat, an attempt at compromise with conservationists.

But the Natural Land Institute, one of the key conservation groups in the region, opposes the plan. The group has said it is not opposed to airport expansion, just this particular design because a busy road bisects the prairie.

The institute has maintained that the airport began the project in 2021 without calling its former conservation partner. When the project began, the Bell Bowl consisted of about 25 acres, but previous construction reduced that amount to the current 15. The expansion is about two-thirds completed.

The airport continues to ignore the group’s concerns, said Kerry Leigh, the Natural Land Institute’s director, despite members going to dozens of airport meetings and offering alternative plans.

“Compromise is over with land protection,” said Leigh. “We have compromised away all of the prairie in Illinois. There is only 1/100 of 1% left. There’s no more compromise.”

After being told by an attorney that the airport intended to start construction later this week, Leigh’s group filed an emergency motion on Monday in a federal appeals court in Chicago to prevent the airport from excavating the prairie for the roadway. The institute also filed a separate petition on Saturday against the Federal Aviation Administration saying an environmental assessment completed last fall was flawed.

Federal and state agencies previously determined that the project would adversely affect the bumble bee but not endanger its existence because the bee would still have plenty of available habitat in the immediate area.

Through its public relations firm, the airport declined to comment “due to litigation.”

Conservationists would like to see the airport reroute its access road around the prairie, preserving all 15 acres.

The airport and FAA did not respond directly to the alternative suggestion. The feds agreed with the airport that design alternatives to preserve more prairie acreage would either result in a much smaller cargo warehouse, which is not economically desirable, or a road that would be more dangerous for heavy truck travel.

The self-proclaimed “fastest growing cargo airport on the planet” has been on an expansion boom driven by growth in international shipping and its role as a cargo hub for Amazon and UPS. For a depressed region that was once a Rust Belt poster child, the airport, which employs 8,500 people who move $3 billion in international goods annually, is an economic engine that has lifted the region.

The expansion plan would add another 50,000 square feet for new cargo tenants and 600 new permanent jobs, the airport has stated.

“[The airport] will retain more than six acres of the Bell Bowl Prairie,” the FAA said in a written statement. “This includes more than three acres of high-quality prairie. Any excavation and shrub and brush clearing work in the project area will occur between October 15 through March 15 to avoid impacts to the Rusty Patched Bumble Bee and avoid the prime nesting seasons for the black-billed cuckoo and the upland sandpiper.”

The preservation of six acres, only half of it considered “high quality” by conservationists, is of little consolation to them.

“They are putting a road through the middle of it,” said Amy Doll, director of Friends of the Illinois Nature Preserves. “The road will be harmful; there will be degradation.”

The airport will likely use salt on the road in the winter, she said. The noise, motion and exhaust of the trucks will disturb the plants, insects, birds and other animals.

“The smaller an ecological system or prairie is, the harder it is to maintain. It loses biodiversity and it’s harder to keep out invasive plants.”

The groups have asked Illinois Gov. JB Pritzker, who has hailed the economic benefits of the expansion in campaign commercials, to use state funds to help reroute the road.

Zachary Nauth is a freelance writer based in Oak Park.