The Rio Grande Natural Area (RGNA) is a distinctive landscape in south central Colorado, in the Sangre de Cristo National Heritage Area near the New Mexico border. It includes the Rio Grande River corridor and its breathtaking cliffs, bluffs, canyons, and river views. This remote area is where Don Diego de Vargas, the Spanish governor of colonial New Mexico made the earliest documented entrada into present day Colorado in 1694.
The RGNA was established by the Rio Grande Natural Area Act in 2006 in order to conserve, restore, and protect natural, historic, cultural, scientiﬁc, scenic, wildlife, and recreational resources of the natural area. Stretching 33 miles, its boundaries include the Rio Grande, from the southern boundary of the Alamosa National Wildlife Refuge to the New Mexico state line, plus lands extending one quarter of a mile on either side of the river bank. The RGNA encompasses approximately 8,800 acres, of which 5,900 acres (67%) is private land and 2,900 acres (34%) is federal lands managed by the Bureau of Land Management (BLM). The RGNA includes a 33-mile stretch of the Rio Grande River, which is also the boundary line between Conejos County to the west and Costilla County to the east. On the Costilla County side, the land is mostly privately owned except for a parcel of county owned land near State Highway 142. The Conejos County side is split approximately 75-25 between BLM and private ownership.