# Colorado aquifers on the well permit register

> Which aquifer each of 600,017 Colorado wells draws on, and how deep you have to go to reach it.

## The aquifers

**175,512** permits draw on one of the four named Denver Basin aquifers, which have their own legal regime and their own depths.

| Aquifer | Permits | Share |
|---|---|---|
| [All Unnamed Aquifers](/aquifer/all-unnamed-aquifers.md) | 465,783 | 77.6% |
| [Not stated](/aquifer/not-stated.md) | 19,134 | 3.2% |
| [Dawson](/aquifer/dawson.md) | 14,024 | 2.3% |
| [Denver](/aquifer/denver.md) | 13,929 | 2.3% |
| [Alluvial](/aquifer/alluvial.md) | 13,890 | 2.3% |
| [Ogallala](/aquifer/ogallala.md) | 11,241 | 1.9% |
| [Arapahoe](/aquifer/arapahoe.md) | 9,456 | 1.6% |
| [Laramie Fox Hills](/aquifer/laramie-fox-hills.md) | 7,796 | 1.3% |
| [Upper Dawson](/aquifer/upper-dawson.md) | 6,943 | 1.2% |
| [Quaternary Alluvium](/aquifer/quaternary-alluvium.md) | 5,403 | 0.9% |
| [Lower Dawson](/aquifer/lower-dawson.md) | 4,944 | 0.8% |
| [Unconfined San Luis Vall](/aquifer/unconfined-san-luis-vall.md) | 3,975 | 0.7% |
| [Unconfined San Luis Valley Aquifer](/aquifer/unconfined-san-luis-valley-aquifer.md) | 3,520 | 0.6% |
| [Laramie-fox Hills](/aquifer/laramie-fox-hills.md) | 2,605 | 0.4% |
| [Confined San Luis Valley](/aquifer/confined-san-luis-valley.md) | 2,551 | 0.4% |
| [Upper Arapahoe](/aquifer/upper-arapahoe.md) | 2,224 | 0.4% |
| [Lower Arapahoe](/aquifer/lower-arapahoe.md) | 2,084 | 0.3% |
| [Dakota](/aquifer/dakota.md) | 1,758 | 0.3% |
| [Confined San Luis Valley Aquifer](/aquifer/confined-san-luis-valley-aquifer.md) | 1,683 | 0.3% |

### What each one is

#### [All Unnamed Aquifers](/aquifer/all-unnamed-aquifers.md)

the Division’s catch-all, and by far the largest group. It means the permit is not tied to one of the named Denver Basin formations.

#### [Not stated](/aquifer/not-stated.md)

an aquifer the Division records under this name.

#### [Dawson](/aquifer/dawson.md)

the shallowest of the four named Denver Basin aquifers.

#### [Denver](/aquifer/denver.md)

a named Denver Basin aquifer, below the Dawson.

#### [Alluvial](/aquifer/alluvial.md)

shallow water in river gravels — easy to reach and closely tied to the surface stream, which is why it is regulated differently.

#### [Ogallala](/aquifer/ogallala.md)

the great High Plains aquifer, under Colorado’s eastern counties.

#### [Arapahoe](/aquifer/arapahoe.md)

a named Denver Basin aquifer, deeper again.

#### [Laramie Fox Hills](/aquifer/laramie-fox-hills.md)

an aquifer the Division records under this name.

#### [Upper Dawson](/aquifer/upper-dawson.md)

an aquifer the Division records under this name.

#### [Quaternary Alluvium](/aquifer/quaternary-alluvium.md)

an aquifer the Division records under this name.

#### [Lower Dawson](/aquifer/lower-dawson.md)

an aquifer the Division records under this name.

#### [Unconfined San Luis Vall](/aquifer/unconfined-san-luis-vall.md)

an aquifer the Division records under this name.

#### [Unconfined San Luis Valley Aquifer](/aquifer/unconfined-san-luis-valley-aquifer.md)

an aquifer the Division records under this name.

#### [Laramie-fox Hills](/aquifer/laramie-fox-hills.md)

the deepest of the four named Denver Basin aquifers.

#### [Confined San Luis Valley](/aquifer/confined-san-luis-valley.md)

an aquifer the Division records under this name.

#### [Upper Arapahoe](/aquifer/upper-arapahoe.md)

an aquifer the Division records under this name.

#### [Lower Arapahoe](/aquifer/lower-arapahoe.md)

an aquifer the Division records under this name.

#### [Dakota](/aquifer/dakota.md)

an aquifer the Division records under this name.

#### [Confined San Luis Valley Aquifer](/aquifer/confined-san-luis-valley-aquifer.md)

an aquifer the Division records under this name.

Which aquifer a well draws on is not administrative detail: it decides how
deep the hole has to be, and it decides which rules apply.
[Depth and yield, county by county](/depth.md).

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Página: https://wells-co.pages.dev/aquifer/
Fonte: Well Application Permit — Colorado Division of Water Resources
Recolha: 2026-08-21