This map loosely represents Western's customer service territories. The boundaries do not exactly match the areas covered by each region's and the management center's hydropower and transmission projects; the region and management center may serve customers outside their "customer service" boundary. The Upper Great Plains Region covers Montana, North and South Dakota, eastern Nebraska, and extreme western Minnesota and Iowa. The Rocky Mountain Region covers Wyoming, western Nebraska, western and northern Kansas and Colorado. The Desert Southwest Region covers the southern tip of Nevada, all but the northeast corner of Arizona, and southern California. The Sierra Nevada Region covers northern California and northern Nevada. The Colorado River Storage Project Management Center covers northeastern Nevada, Utah, New Mexico, west Texas, and the northeastern corner of Arizona.