Geography of the Upper Colorado River Planning Area

The Upper Colorado River Planning Area encompasses about 11,860 square miles (sq. mi.) and includes the Big Sandy, Bill Williams, Detrital Valley, Hualapai Valley, Lake Havasu, Lake Mohave, Meadview, Peach Springs and Sacramento Valley basins. Basin boundaries, counties and prominent cities, towns and places are shown in Figure 4.0-2.  The planning area is bounded on the north by the Colorado River, the state of Nevada and by the Western Plateau Planning Area, on the east by the Central Highlands Planning Area and the Prescott Active Management Area, on the south by the Lower Colorado River Planning Area and a portion of the Central Highlands Planning Area and on the west by the Colorado River and the states of California and Nevada. (See Arizona Planning Areas Map)  The planning area includes all or part of five watersheds, which are discussed in Section 4.0.2. Within the planning area, the Fort Mojave Indian Reservation encompasses about 23,500 acres and the Hualapai Indian Reservation encompasses about 553,000 acres.  Elevation ranges from 450 feet along the Colorado River near Lake Havasu City to 8,417 feet at Hualapai Peak south of Kingman.

Figure 4.0-2  Upper Colorado River Arizona Planning Area

Figure 4.0-3 Physiographic Provinces of Arizona

Arizona’s three physiographic regions are found in the planning area (Figure 4.0-3).  Most of the planning area is within the Basin and Range physiographic province, which is characterized by northwest-southeast trending mountain ranges separated by broad alluvial valleys.  The Detrital Valley and Sacramento Valley basins are representative of this province. The northeastern portion of the planning area, primarily the Peach Springs Basin, falls within the Colorado Plateau physiographic province, characterized by high desert plateaus and incised canyons.  The central eastern portion of the planning area that includes the eastern, upland areas of the Big Sandy and Bill Williams basins is located within the Central Highlands transition zone, characterized by rugged mountains of igneous, metamorphic and sedimentary rocks. 

Unique geographic features of the planning area include the the Colorado River and associated lakes impounded by several dams.  The river and lakes influence cultural uses, groundwater conditions and habitat in a significant portion of the planning area.

For more information on Geography see individual basins in the directory to the right.

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