Abstract The Groundwater Appropriators of the South Platte River Basin, Inc. (GASP) was a non-profit well-augmentation company, the first organization of its kind in Colorado. Founded in 1972, its purpose was to offset depletions to the South Platte River caused by pumping of the South Platte valley-fill aquifer. At its peak, GASP served more than 3,000 wells in northeastern Colorado. As state regulation of this activity was modified, the company ceased operations in 2003 and sold the last of its...