Groundwater Other Than Tributary

Different Types of Groundwater

Coloradans rely heavily on groundwater for a variety of municipal, agricultural, industrial and other uses. Tributary groundwater is connected to a natural stream system through either surface or underground flows and 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 nontributary 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 (see WEco’s Citizen’s Guide to Colorado 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 (DWR), also known as the State Engineer’s Office.

Designated Groundwater

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 15 years” prior to initiation of a designated basin.

There are currently eight designated basins located on 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. Within the Designated Basins there are 13 locally controlled Ground Water Management Districts which have some additional authority to administer groundwater within their boundaries.

Designated groundwater is administered under a separate legal regime from other waters of the state with the Colorado Ground Water Commission having administrative authority rather than the state’s courts. In 1965, the Colorado General Assembly created the Colorado Ground Water Commission, the regulatory and permitting agency authorized to manage and control groundwater use in designated groundwater basins and establish designated basins. The Commission may hold rulemaking and adjudicatory hearings, subject to judicial review by a groundwater judge. 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: www.courts.state.co.us.

Nontributary Groundwater

Nontributary groundwater is water outside of a designated groundwater basin, the pumping of which will not materially impact a surface stream in 100 years at a rate greater than 0.1 percent of the annual rate of withdrawal. An overlying landowner may obtain a permit to pump the amount of water underlying their land on the basis of a 100-year aquifer life, that is, one percent of that amount annually. This is not a guarantee that a 100-year supply of water actually exists beneath the land.

Geothermal Resources

All subsurface geothermal fluids are considered part of the state’s groundwater resources and are subject to the Colorado Geothermal Resources Act. Use of this resource requires a permit from the state engineer, as with all other types of groundwater extraction.

Denver Basin Groundwater: Not Nontributary and Nontributary

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.

Permit Requirements and 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. Use rights depend on the groundwater source and the type of beneficial use.

In order to obtain a permit to drill a well, one must file an application with the Division of Water Resources. To obtain a water right decree for tributary groundwater, one must file an application with 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. DWR also has authority to adopt and amend tributary, nontributary and Denver Basin groundwater rules and regulations that are subject to water court review.

The designated groundwater permit system was designed to protect and maintain reasonable groundwater pumping levels. DWR assists the Colorado Ground Water Commission in issuing designated groundwater permit applications. Designated groundwater is allocated and administered in a coordinated manner by DWR, the 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 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. The Denver Basin statutes and rules are in place because the Colorado General Assembly recognized that this groundwater is of great economic importance to overlying landowners and to local public water suppliers and therefore should be available for present and future use, to the extent that it exists.

Geothermal resources are administered and managed according to the Geothermal Well Rules by DWR.

For more information on well permits see the Beginner’s Guide to Well Permits published by DWR on its website: dwr. colorado.gov/services/well-permitting. Denver Basin Aquifers