SALT LAKE CITY, Utah (AP) — Four Utah ski resorts are backing out of proposed land swaps that would have set aside some of their mountainside terrain for conservation in exchange for public lands near their bases.

The resorts made the decision after determining their lands on the steep slopes are worth so much less that they would have trade 100-200 acres for a single acre near the bases, The Salt Lake Tribune reports.

The breakdown of the proposal illustrates the difficulty of working out land swaps for public lands that have high commercial value.

Executives with Solitude, Brighton, Snowbird and Alta resorts informed the Central Wasatch Commission of their decision in a Nov. 1 letter. They encouraged the commission to instead focus efforts on to improve transportation methods and reduce traffic up the Little and Big Cottonwood Canyons.

“We take seriously our stewardship of the private and public lands within our permitted area,” said Solitude President Kim Mayhew. “We are open to all kinds of different conversations with our partners that will support minimizing the impact on the delicate environment of Big Cottonwood Canyon.”

Solitude will implement one such measure this ski season as it charges for parking, including a $20 fee for people not carpooling.

The resorts would still like to get more lands around the bases but it’s difficult to find a way that happens, said Central Wasatch Commission Executive Director Ralph Becker.

Some critics of the land swaps considered them “land grabs” that would benefit the ski resorts and not help the environment much. Much of the lands the ski resorts were set to exchange have mine shafts and tailing piles.