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State Engineer’s Office Info

Colorado Water Law

Colorado water law follows the system of prior appropriation.  The prior appropriation “doctrine” is a system of allocating water rights from a water body or source (surface water or groundwater) that has evolved in the American West since the mid-1800s due to the scarcity of water.

Surface Water

Surface water rights are regulated in Douglas County under the Doctrine of Prior Appropriation. The Doctrine of Prior Appropriation can be summarized in the following phrase: “first in time/first in right.” This means that the first person to “beneficially” use water from a body of water becomes the senior water rights holder (the water is appropriated), and has the right to continue to use that quantity of water for that purpose. The remaining water on that body of water can be used by subsequent users, the junior water rights holders, for their own beneficial purposes, provided they do not harm the rights of senior water users. Each water right has an appropriation date and a yearly quantity of water that may be used. In times of drought, senior water right holders can use their appropriated water provided the water source can supply it. This is regardless of whether or not there is enough water left for junior water holders; however, depending on the available water, junior water holders may receive a portion of their full allocation.

Acquiring a valid water right necessitates establishing intent to divert water, which is the act of diverting the water and applying it to a beneficial use. In addition, surface water rights are not connected to land ownership and can, with certain restrictions, be sold and acquired as surface property.

The term “beneficial use” is important because it historically establishes the foundation, measure, and limit of the water for that water right holder. The definition of beneficial use is commonly delineated for household, agricultural and industrial purposes. According to Colorado water law, beneficial use is broadly defined as a lawful appropriation that employs reasonably efficient practices to put that water to use without waste. In order to have enough water available to as many water rightholders as possible, avoiding water waste is the goal. The uses that are considered beneficial have evolved and increased in response to Colorado’s changing community and economic values. For example, an environmental and ecological purpose, such as maintaining the wildlife habitat that is dependent on a natural body of water, is now considered to be a beneficial use under Colorado water law.


Groundwater in Colorado is administered and managed under four categories identified below.  Designated groundwater, non-tributary groundwater, and Denver Basin groundwater are not subject to the Doctrine of Prior Appropriation discussed in detail under the surface water section.

  1. Tributary Groundwater
    Tributary ground water is water in an aquifer that is hydraulically connected to surface water, meaning if you pull water out of the ground you have an impact on the surface water flows of the stream.  Examples of tributary groundwater in Douglas County are the alluvial aquifers that underlie the South Platte River and Cherry Creek.  In contrast, deep groundwater is not measurably connected to surface water due to the confining layers that overly the aquifer.  The State Engineer’s Office issues or denies well permits for appropriation of tributary groundwater.
  2. Designated Groundwater
    Designated groundwater is managed by the Colorado Ground Water Commission.  There are no designated groundwater basins within Douglas County.  Please visit the Colorado Division of Water Resources, if you are interested in additional information.
  3. Non-Tributary Ground Water
    Non-tributary groundwater is water that is physically separated from surface water by impermeable layers in the aquifer.  It is also considered non-tributary when the groundwater is at such a great distance from the surface water that it has little or no hydraulic connection with it.  In a non-tributary aquifer, the landowner overlying the aquifer has the ability to pump the groundwater as long as it will not affect surface water levels at an annual rate greater than one-tenth of one percent of the annual rate of withdrawal within 100 years.  Under this system of water management, obtaining and exercising non-tributary groundwater rights emulates the basic concepts of beneficial use, non-waste, and anti-speculation.
  4. Denver Basin Ground Water
    Denver Basin groundwater is presumed not to be tributary in nature.  Water from the Denver Basin refers to deep groundwater withdrawn from one of its four aquifers – Dawson, Denver, Arapahoe, and Laramie-Fox Hills.  The Denver Basin contains two types of legally designated groundwater, non-tributary and not non-tributary Denver Basin groundwater is allocated to overlying landowners, and rights to withdraw water are subject to augmentation requirements under the two separate legal designations.  Not non-tributary groundwater is legally defined as groundwater located within those portions of the Denver Basin aquifers that are outside the boundaries of any designated basin and will, within 100 years, deplete the flow of a natural stream at an annual rate greater than one-tenth of one percent of the annual rate of withdrawal.  Pumping not-non-tributary groundwater requires an augmentation plan from the State Engineer’s Office and varies in the amount of required return flow based on the proposed aquifer and the location of the well with respect to the stream/aquifer connection.

Denver Basin Rules

The Denver Basin Rules (the rules) apply to the Dawson, Denver, Arapahoe and Laramie-Fox Hills aquifers in the Denver Basin, and provide estimated saturated thickness and specific yields of each aquifer.  The Office of the State Engineer uses the rules to evaluate and determine the amount of groundwater available for withdrawal where no specific site data is available.  Upon evaluation under these criteria, a well permit may or may not be issued.  The applicant can augment the values with site-specific well log data, which demonstrates that the actual aquifer characteristics are different from the general information given in the rules.

Groundwater Well Permitting

There are two statutes that govern the permitting of wells, CRS Sections 37-90-137 and 37-92-602.  Well permitting under Section 137 is for “non-exempt” wells and permitting under Section 602 is for “exempt” wells.

For more information visit https://dwr.colorado.gov/services/well-construction-inspection

Non-Exempt Wells

Non-exempt wells include municipal, irrigation, commercial and industrial wells, but sometimes include certain residential wells on tracts of 35 acres, or larger.  If a well on a 35-acre tract diverts more than 1-acre foot per year, then it is also considered a non-exempt well.  Additionally, residential wells on tracts less than 35 acres are non-exempt if the use is going to be greater than household use only.

The Colorado Division of Water Resources may impose specific well spacing standards to wells with high rates of pumping.  This is done to ensure that such wells do not interfere with other existing wells nearby.

Exempt Wells

Exempt wells include: (a) household use only wells (limited to a maximum pumping rate of 15 gpm, up to a maximum annual volume of 0.33-acre feet per year, and with no outside uses allowed); (b) commercial exempt wells (limited to a maximum pumping rate of 15 gpm, up to a maximum annual volume of 0.33-acre feet per year, and no outside uses allowed); and (c) domestic wells which by definition, means a single well on a 35-acre or larger tract that will be the only well on that tract and will not exceed a pumping rate of 15 gpm and an annual use of 1-acre foot. The reason that the exempt wells in (a) and (b) say “up to a maximum of 0.33-acre feet per year” is because that is the maximum allowed by statute, but if there is less than 0.33-acre feet per year legally available beneath the property, the permit could allow less water usage. If, by virtue of the location of the property, use of the proposed water supply needs an augmentation plan, the well has to be permitted as a non-exempt well regardless of parcel size or the volume of water that is desired to be extracted.

In summary, there is not a well spacing requirement for any individual residential well. If the permitted pumping rate is equal to, or less than 15 gpm, it will be permitted as an exempt domestic well, an exempt well in a cluster 35 development, or as a non-exempt residential well on a parcel of any size.