This map shows the four regions that make up our service territory. The Sierra Nevada Region includes the northern two thirds of California and most of Nevada. The Desert Southwest Region includes the southern tip of Nevada, all of Utah, Arizona and New Mexico, and the western edge of Texas. The Rocky Mountain Region comprises the eastern two-thirds of Wyoming, all of Colorado, the western third of Nebraska and the western third and top half of Kansas. The Upper Great Plains Region includes the eastern two-thirds of Montana, all of North and South Dakota, the eastern two-thirds of Nebraska and parts of Iowa and Minnesota.