San Juan Mountains Wilderness Act

San Juan Mountains Wilderness Act- (Sec. 3) Designates specified lands in the Grand Mesa, Uncompahgre, and Gunnison National Forests and specified land of the Bureau of Land Management (BLM) in Colorado as parts of the Lizard Head Wilderness and of the Mount Sneffels Wilderness in the National Wilderness Preservation System.

Designates certain BLM land as the McKenna Peak Wilderness.

(Sec. 4) Designates specified lands in such National Forests and San Juan National Forest as the Sheep Mountain Special Management Area (the Special Management Area).

Requires the Secretary of Agriculture (USDA) to manage the Special Management Area in a manner that: (1) conserves, protects, and enhances the resources and values of such Area; and (2) maintains or improves its wilderness character for potential inclusion in the System.

Prohibits the use in the Special Management Area of: (1) permanent roads; (2) motor vehicles, motorized equipment, or mechanical transport, except for administrative purposes; and (3) the establishment of temporary roads, except also for administrative purposes.

Permits the continuation within the Special Management Area of any activities (including helicopter access for recreation and maintenance) authorized by permit or license. Prohibits the designation of the special management area from affecting the issuance of permits related to those activities after the enactment of this Act.

Requires water and water rights in the Area to be administered in accordance with the Colorado Wilderness Act of 1993.

(Sec. 5) Allows the Secretary to continue to authorize the competitive running event permitted since 1992 in the vicinity of the Special Management Area, the Liberty Bell East Special Management Area, and the Liberty Bell addition to the Mount Sneffels Wilderness designated by this Act in a manner compatible with the preservation of those areas as wilderness.

Declares that nothing in this Act affects the jurisdiction or responsibility of the state of Colorado respecting fish and wildlife.

Declares that nothing in this Act creates a protective perimeter or buffer zone around the wilderness areas and the Special Management Area designated by this Act (the covered land). Declares that the fact that a nonwilderness activity or use on land outside of the covered land can be seen or heard from within the covered land shall not preclude the conduct of the activity or use outside the boundary of the covered land.

Allows the Secretary or the Secretary of the Interior, as appropriate, to acquire any land or interests in land within the boundaries of the Special Management Area or the designated wilderness areas only through exchange, donation, or purchase from a willing seller.

Requires continued permission of livestock grazing already established on the covered land.

Withdraws the covered land, the land identified as the proposed Naturita Canyon Mineral Withdrawal Area, and the proposed Liberty Bell East Special Management Area from: (1) entry, appropriation, and disposal under the public land laws; (2) location, entry, and patent under the mining laws; and (3) operation of the mineral leasing, mineral materials, and geothermal leasing laws.

Prohibits the use of motor vehicles, motorized equipment, or mechanized transport in the proposed Liberty Bell East Special Management Area.

Releases certain parts of the Dominguez Canyon Wilderness Study Area that were not designated as wilderness by this Act from further study for designation as wilderness.