Region
Colorado River Watershed (Colo.-Mexico)
51
Colorado
6
Colorado River (Colo.-Mexico)
5
West (U.S.)
4
United States
3
Arizona
2
Columbia River Watershed
2
Utah
2
California
1
Glen Canyon Dam (Ariz.)
1
Glen Canyon Region (Utah and Ariz.)
1
Green River (Utah)
1
Hoover Dam (Ariz. and Nev.)
1
Missouri River Watershed
1
New Mexico
1
Pacific Coast
1
Pacific slope basins
1
Southwest, New
1
Wyoming
1