Coloradans rely heavily on groundwater for a variety of municipal, agricultural, industrial and other uses. Tributary groundwater is recharged from precipitation including seasonal runoff from snowmelt and irrigation return flows. All groundwater in Colorado is presumed to be tributary unless shown to be non-tributary to a surface stream. Colorado’s prior appropriation system regulates tributary groundwater.
Groundwater other than tributary groundwater is allocated and administered as designated, nontributary, or Denver Basin groundwater. Geothermal groundwater is another classification of groundwater; it can be tributary or nontributary and is regulated by the Geothermal Resources Act and administered by the Colorado Division of Water Resources.
Managed by the Colorado Ground Water Commission, Colorado statutes define designated groundwater as groundwater “which in its natural course would not be available to and required for the fulfillment of decreed surface rights.” It also includes groundwater “in areas not adjacent to a continuously flowing stream wherein groundwater withdrawals have constituted the principal water usage for at least fifteen years” prior to initiation of a designated basin.
In 1965, the Colorado General Assembly authorized the Colorado Ground Water Commission to create eight designated groundwater basins in Colorado’s Eastern Plains: Kiowa Bijou, Southern High Plains, Upper Black Squirrel Creek, Lost Creek, Camp Creek, Upper Big Sandy, Upper Crow Creek and Northern High Plains.
Appeals in designated groundwater basin cases go before groundwater judges appointed by the Chief Justice of the Colorado Supreme Court. To learn more, see “water courts” on the Colorado Judicial Branch website.
Nontributary groundwater is water outside of a designated groundwater basin, the pumping of which is presumed not to materially impact a surface stream. An overlying landowner may obtain a permit to pump this water assuming a 100-year period, subject to limitations intended to prevent streams from being depleted at an annual rate greater than one-tenth of one percent of the annual rate of withdrawal. This is not a guarantee that a 100-year supply of water actually exists beneath the land.
Denver Basin Groundwater: A Special Case
Denver Basin groundwater is water within the Dawson, Denver, Arapahoe and Laramie-Fox Hills aquifers located on Colorado’s Eastern Slope between Greeley and Colorado Springs, and bounded by the foothills to the west and Limon to the east. There are two types of Denver Basin groundwater and both require some measure of protection for water rights decreed for surface streams.
“Not nontributary” is closer to surface streams and its use requires at least 4 percent of the water pumped to be returned to the surface stream and in some instances, actual replacement of depletions. Use of “nontributary” groundwater in the Denver Basin aquifers requires relinquishment of 2 percent of the water pumped.
An overlying landowner may obtain a permit to pump this water assuming a 100-year period, subject to limitations intended to prevent a natural stream from being depleted at an annual rate greater than one-tenth of one percent of the annual rate of withdrawal.
All subsurface geothermal fluids are considered part of the state’s groundwater resources and are subject to the Colorado Geothermal Resources Act. Geothermal resources are administered and managed according to the “Geothermal Well Rules” by the Colorado Division of Water Resources.
Permit Requirements & Use Rights
According to the 1965 Ground Water Management Act, every new well in Colorado that diverts tributary, nontributary, designated groundwater, Denver Basin groundwater or geothermal resources must have a permit. Groundwater use rights depend on the source of the groundwater and the type of beneficial use.
In order to obtain a permit to drill a well, one must file an application with the Colorado Division of Water Resources. To obtain a water right decree for tributary groundwater, one must file required documentation to the regional water court. When well permit applications are submitted, division staff determine the amount of groundwater available, the potential for groundwater use to injure other existing water rights and whether or not the withdrawal will be unreasonably wasteful.
Designated groundwater is allocated and administered in a coordinated manner by the Division of Water Resources, Colorado Ground Water Commission and local groundwater management districts. The regional water court issues decrees for the non-designated aquifers of the Denver Basin.
Statutes also allow public entities, such as cities and water districts, to claim and use Denver Basin groundwater underlying the lands of others if the entity makes water service available to the landowners and if the landowners have not already claimed the groundwater rights by obtaining a court decree or a well permit from the State Engineer.
For a detailed description of the well permit application process, different types of wells and other subjects related to groundwater management, see the Guide to Colorado Well Permits, Water Rights and Water Administration published by the Colorado Division of Water Resources on its website: www.water.state.co.us/groundwater.