Some of the group’s money has come from corporations, or wealthy donors with corporate ties. The group has been dogged for decades by questions about whether it is too close to those corporate interests, as well as whether it has permitted too much development and other economic use of its lands.

The Texas property, known as the Texas City Prairie Preserve, has a complex history.

Mobil Oil donated the 2,300-acre property, near Galveston Bay, to the Nature Conservancy in 1995, in a bid to save the Attwater’s prairie chicken. That bird, known for its colorful mating dance, was once widespread on the Texas coastal prairies, but was devastated by hunting and destruction of its habitat.

Gas and oil were being produced on the Texas City property at the time the land was donated, but relatively far from the breeding grounds of the prairie chicken. In 1999, the Nature Conservancy’s Texas chapter decided to permit new drilling there, with the idea of dedicating the money to prairie chicken conservation. It sought out a deal with an energy company and a new well was drilled, about a half-mile from the primary breeding grounds.

The drilling was exposed by The Los Angeles Times in 2002, and explored in more detail a year later by The Washington Post, in a series of articles that raised broad questions about the activities the Nature Conservancy was permitting on conservation lands. A two-year Senate investigation sharply criticized the Nature Conservancy.

The group instituted reforms, including a pledge by its then-president that it would not permit new oil drilling or mining on its lands, and the managers of the organization have largely been replaced in the intervening years. The no-new-drilling pledge had one important caveat: that the conservancy would honor existing legal agreements.

Documents show that the well on the Texas City preserve petered out in 2003, and efforts to revive it were abandoned in 2004. The oil company holding the lease sought to drill a replacement well.

Mr. Petterson said the Nature Conservancy was reluctant to allow that, given the no-drilling pledge, and sought a legal opinion. An outside lawyer ruled that the terms of a 1999 lease, as well as a related legal settlement over royalties, effectively gave the oil company the right to drill again.