Rio Grande Natural Area Act

Directs the Commission to assist the Secretary in implementing such management plan by carrying out authorized activities to preserve and interpret the Area's natural, historic, cultural, scientific, scenic, wildlife, and recreational resources which include allowing the Commission to: (1) assist the State of Colorado in preserving State land and wildlife within the Area; (2) encourage the political subdivisions of the State to adopt and implement land use policies that are consistent with the Area's management and such management plan; and (3) encourage and assist private landowners in the Area in the implementation of the management plan.

(Sec. 6) Directs the Secretary to prepare a management plan relating to the management of Federal land in the Area. Requires the Commission to submit its management plan for the management of the non-Federal land in the Area to the Secretary for approval or disapproval. Instructs the Secretary and the Commission to cooperate to ensure that the management plans are consistent.

Sets forth specified requirements regarding the preparation of the management plans. Requires the Secretary to publish notice of such plans in the Federal Register.

(Sec. 7) Requires the Secretary to administer the Federal land in the Area in accordance with the laws applicable to public land and the management plan for such land and in a manner that provides for: (1) the purposes described in this Act; (2) the continued use of the Area for education, scientific study, and limited public recreation purposes in a manner that does not substantially impair the purposes for which the Area was established; (3) the protection of the wildlife habitat of the Area; (4) a prohibition on the construction of water storage facilities in the Area; and (5) the reduction in the use or removal of roads in the Area and the reduction in or prohibition against the use of motorized vehicles in the Area, including the removal of roads and a prohibition against motorized use on Federal land in the area on the western side of the Rio Grande River from Lobatos Bridge south to the New Mexico State line.

Encourages the Secretary to negotiate with the State, the Rio Grande Water Conservation District, and affected water users in the State to determine if changes in the streamflow that are beneficial to the Area may be accommodated.

Applies the management plan for the non-Federal land to private land in the Area only if the private landowner agrees to be bound by such plan.

Withdraws all Federal land in the Area from: (1) all forms of entry, appropriation, or disposal under the public land laws; (2) location, entry, and patent under the mining laws; and (3) disposition under the mineral leasing laws (including geothermal leasing laws).

Permits the Secretary to acquire land or an interest in land within the Area from willing sellers. Requires any acquired land or interest to be administered in accordance with the management plan for the Federal land and this Act.

Prohibits applying to the Area Wild and Scenic Rivers Act requirements that Federal agencies consider potential national wild, scenic, and recreational river areas in planning for the use and development of water and related land resources.

(Sec. 8) States that nothing in this Act: (1) amends, modifies, or is in conflict with the Rio Grande Compact; (2) authorizes the regulation of private land in the Area; (3) authorizes the imposition of any mandatory streamflow requirements; (4) creates an express or implied Federal reserved water right; (5) imposes any Federal water quality standard within or upstream of the Area that is more restrictive than would be applicable had the Area not been established; or (6) prevents the State from acquiring an instream flow through the Area under the terms, conditions, and limitation of State law to assist in protecting the natural environment to the extent and for the purposes authorized by State law.

(Sec. 9) Authorizes appropriations.

(Sec. 10) Terminates the Commission ten years after the enactment of this Act.