Statutory Ground-Water Categories
Under Colorado law, ground water is classified under five primary categories: geothermal, tributary, non-tributary, not non-tributary, and designated. All subsurface geothermal fluids are part of the state’s ground-water resources and are subject to the Colorado Geothermal Resources Act. Tributary ground water is water in the unconsolidated alluvial aquifer and water hydrologically connected thereto. Non-tributary ground water is ground water located outside the boundaries of any designated ground water basin in existence on January 1, 1985, the withdrawal of which will not deplete the flow of a natural stream at a specified rate over a specified time period. Not non-tributary is a special class of ground water specific to the Denver Basin that is similar to tributary ground water. Designated ground water is non-tributary ground water within the geographic boundaries of a designated ground water basin. The establishment and management of designated ground-water basins are delegated to the Colorado Ground Water Commission (http://water.state.co.us/cgwc/). Currently, there are eight designated basins (Figure 3.2) that contain 13 Ground Water Management Districts.
Figure 3.2 The Colorado Ground Water Commission has established
eight designated ground-water basins.