Florida International University is pursuing a complicated land swap that would allow it to expand into the county fairgrounds next door.

The key to the deal: 350 acres of West Miami-Dade wetlands the state bought 13 years ago for $3.7 million as part of an Everglades restoration project since scrapped by the South Florida Water Management District.

FIU’s plan calls for securing the parcel at an attractive price — a free, 99-year lease — and then giving it to Miami-Dade County in exchange for the existing 87-acre fairgrounds. A new home for the 60-year-old Miami-Dade County Fair & Exposition, as well as a county park, would then be constructed on the new site.

FIU pitches the proposal as a win-win, helping a university with a fast-growing medical school that has run out of real estate while also preserving undeveloped land near the Everglades.

Environmentalists haven’t been won over.

They contend the plan would destroy wading bird habitat, encourage building beyond the county’s urban development boundary and short-change the state’s cash-strapped Everglades restoration efforts. They’re also concerned FIU is trying to fast-track a deal that has undergone little public scrutiny, pointing to legislative language circulating in Tallahassee that would authorize the transfer.

“FIU is flexing its political muscle to try to push this,” said Laura Reynolds, executive director of The Tropical Audubon Society.

Sandra Gonzalez-Levy, FIU’s senior vice president for external relations, said she wasn’t certain who wrote the proposed legislation but insisted FIU was not trying to ram through a deal. She also acknowledged the proposal faces legal and political hurdles, including possible conservation covenants and wetlands development restrictions. Under the county charter, voters would have to approve the plan in a countywide referendum before FIU could build on the old fairground .

“We are in a discovery and exploratory phase right now, so there are many questions that are still unanswered,” she said, adding that FIU welcomed public review of the proposal.

With the school projecting attendance to grow by 10,000 over the next five years, she said FIU must find more space. Even with planned additions at its North Miami campus, FIU needs more room for labs, its new Herbert Wertheim College of Medicine and med student housing.

For FIU, the fairground has an obvious advantage of being next door to its main campus at the junction of Tamiami Trail and Florida’s Turnpike. The fair moved there in 1972, a few years after FIU’s establishment.

The university broached the expansion about a year ago, meeting with Miami-Dade’s Parks and Recreation Department, which owns the fairgrounds, and the non-profit company that runs the fair under a 90-year lease signed in 1995. Both agreed to join a group to evaluate potential new fairground locations, evaluating 16 sites that fit the criteria of at least 250 acres, most needed for parking up to 18,000 cars. The fair, which attracts more than 500,000 patrons each March and ranks as the largest in the state, also rents three exhibition halls many weekends.

Manny Rodriguez, chairman of the board of Miami-Dade Fair & Exposition Inc. and a regional director for Florida Power & Light, said the fair’s board was open to helping FIU — “a valuable entity in this community” — if the right spot could be found.