Conservation. The Last Water Hole in the West is the history of the largest transmountain diversion project ever built ---- the Colorado-Big Thompson (C-BT) --- designed to bring Colorado River water through a thriteen-mile tunnel under the Continental Divide to farmers in the South Platte River basin. The book also offers a detailed exploration of the Northern Colorado Water Conservancy District (NCWCD), the agency created to oversee the design, construction, water delivery, and payment of the monumental C-BT.