The Santa Clara/Gunlock Area of Critical Environmental Concern is a 1,998-acre property that is severely at-risk because of rampant off-road motorized vehicle travel in the area. On the property are numerous Ancestral Puebloan riverine sites, abandoned Southern Paiute sites and several locations dense with petroglyphs and pictographs. As this property straddles the Santa Clara River, it is also essential habitat for the Virgin spinedace minnow and potential habitat for the federally-endangered Southwestern willow flycatcher.

The property is stretched out along the Santa Clara River valley between Gunlock Reservoir and the Shivwits Indian Reservation, about eleven miles northwest of St. George.