Environmentalists want federal land managers to suspend efforts to amend a plan that would guide oil and gas development and other activities near Chaco Culture National Historical Park.

Lawmakers from the country's largest American Indian reservation may have thrown a wrinkle into efforts aimed at establishing a permanent buffer around Chaco Culture National Historical Park, as New Mexico's congressional delegation, environmentalists and other tribes try to keep oil and gas development from getting closer to the World Heritage site.

Navajo Nation President Jonathan Nez and Vice President Myron Lizer extended their appreciation to U.S. House Assistant Speaker Ben Ray Luján (D-N.M.) for securing a one-year moratorium on oil and gas drilling near the Chaco Culture National Historical Park.