Rocky Mountain National Park Wilderness and Indian Peaks Wilderness Expansion Act - (Sec. 3) Designates certain lands in Rocky Mountain National Park, Colorado, as wilderness (the Wilderness) and as a component of the National Wilderness Preservation System. Provides for the inclusion of specified potential wilderness land in the Wilderness. Excludes specified land from such Wilderness.
Sets forth provisions: (1) for the administration of any land designated as wilderness under this section or added to the Wilderness after enactment of this Act; and (2) regarding water rights and fire, insect, and disease control.
(Sec. 4) Sets forth provisions: (1) governing continued operations at the Grand River Ditch; and (2) concerning the Alva B. Adams Tunnel and other Colorado-Big Thompson Project facilities.
(Sec. 5) Directs the Secretary of the Interior to establish an alignment line and identify the boundaries for the East Shore Trail within the East Shore Trail Area. Authorizes necessary adjustments in such boundaries to protect resources, if the adjustment would not place any portion of the Trail in such Wilderness. Includes any portion of the Area that is not traversed by the Trail, that is not west of the Trail, and that is not within 50 feet of the centerline of the Trail in such Wilderness.
Prohibits any use of motorized vehicles and other motorized machinery in the Area that was not permitted on March 1, 2006. Requires the Area, until the Secretary authorizes the construction of the Trail and the use of it for non-motorized bicycles, to be managed to: (1) protect any wilderness characteristics; and (2) maintain the suitability of the Area for inclusion in the Wilderness.
(Sec. 6) Amends the Indian Peaks Wilderness Area, the Arapaho National Recreation Area and the Oregon Islands Wilderness Area Act to adjust the boundaries of: (1) the Indian Peaks Wilderness Area; and (2) the Arapaho National Recreation Area.
(Sec. 7) Applies provisions governing leases of National Park System buildings and property to property known as the Leiffer tract near the Park's eastern boundary in Larimer County, Colorado.