Undeveloped oil and gas leases are tying up more than half a million acres of public land in the Cowboy State.

According to a report released Tuesday by The Wilderness Society, almost 600,000 acres are sitting idle because oil and gas companies who bought the leases never developed them.

Nada Culver with The Wilderness Society says the Bureau of Land Management (BLM) improperly suspends many leases.

"One of the most egregious examples we saw were four leases that were suspended in 1994," said Culver. "The reason for that suspension expired three years later in 1997, but those suspensions stayed in place until 2004 for three of them and one still seems to be in place."

Researchers say it's a problem when public land accrues no benefit to the taxpayer, plus the leases prevent the BLM from developing the properties for wind or solar, or managing them for recreation or conservation.