Park County Groundwater Study

OF-15-11 Geology and Groundwater Resources of Park County


Barkmann, P. E., L. A. Sebol, F. S. Fitzgerald, and W. Curtiss. “OF-15-11 Geology and Groundwater Resources of Park County.” Geology and Groundwater. Open-File Reports. Golden, CO: Colorado Geological Survey, 2015.

Park County has experienced considerable population growth in recent decades with development becoming increasingly reliant on local groundwater resources. A diverse geologic setting characterizes the county and groundwater may be found in many of those settings. This product compiles the most recent geologic mapping and interpretations focusing on groundwater occurrences in the various geologic formations found in the area. It is intended to provide a regional overview with the general public in mind, although it contains detailed background that may be beneficial to more technical users.

Available for download:

Report text with figures (does not include plates!)
ArcGIS shape files and layers

Individual figures and plates

1. Regional Map of Park County.
2. Park County Stratigraphic Column.
3. Structural Setting of Park County.
4. Principal Structural Features in Park County.
5. Pre-South Park Formation Outcrop Patterns.
6. Map of Structural Zones in Park County.
7. Average Annual Precipitation over Park County.
8. Generalized Direction of Groundwater Flow in Park County.

List of Plates

1. Geologic Map of Park County.
2. Cross-sections Through Park County.
3. Hydrogeologic Unit Map: Precambrian Crystalline Bedrock.
4. Hydrogeologic Unit Map: Tertiary and Cretaceous Intrusive and Volcanic Igneous Rocks.
5. Hydrogeologic Unit Map: Older Paleozoic Formations.
6. Hydrogeologic Unit Map: Belden Formation.
7. Hydrogeologic Unit Map: Minturn Formation.
8. Hydrogeologic Unit Map: Maroon Formation.
9. Hydrogeologic Unit Map: Garo Sandstone.
10. Hydrogeologic Unit Map: Morrison Formation.
11. Hydrogeologic Unit Map: Dakota Sandstone.
12. Hydrogeologic Unit Map: Benton/Niobrara.
13. Hydrogeologic Unit Map: Pierre Shale.
14. Hydrogeologic Unit Map: Laramie-Fox Hills Aquifer.
15. Hydrogeologic Unit Map: Laramide Sedimentary Units.
16. Hydrogeologic Unit Map: Tallahassee Creek Conglomerate.
17. Hydrogeologic Unit Map: Antero Formation.
18. Hydrogeologic Unit Map: Wagontongue-Trump Formation.
19. Hydrogeologic Unit Map: Unconsolidated Quaternary Deposits.

GIS information

An ArcGIS-based map (mxd) hosted on here allows the viewer to alternate between layers to understand the three-dimensional characteristics of the regions.

ArcGIS shape files and layers are available as geodatabases, plus as a map package with ArcGIS 10.0+ compatibility.

The ArcGIS-based map is zoomable and layers may be turned on and off to view the various geologic layers. General instructions/helpful hints for navigating on maps hosted by are as follows:

  • When you first open this project you will notice in the left hand corner “Contents” and the name “ParkCounty AquiferComb 15 06 30 online”, click on this heading.
  • Next you will notice many different categories in which you can also click on to see further data under those headings.
  • Each group or layer can be turned off and on by checking or unchecking the box next to it. Click on the name of the layer to expand the sub-layers, as needed.
  • The Group is hierarchical with the header being the highest point and can turn on everything underneath if everything is checked in that group.
  • One can zoom in or out using the + and – sign in the top left hand corner of the Geography box or by using a scrollable mouse wheel.
  • Clicking the House button will take you back to the initial start state of the map, which is the boundary of Park County.
  • Well files have a Total Depth (TD) and Water Level (WL) in feet. The “nl” labels mean that the depth or water level were “Not listed” in the DWR database.

Disclaimer: These data are intended for use at 1:50,000 scale and are checked for accuracy accordingly. The CGS does not assume responsibility for the use of these data.

The report is organized as follows:

Table Of Contents

List Of Figures
List Of Plates
List of Tables


Background and Purpose

General Geology Of Park County

Regional Setting
Major Rock Units and Stratigraphy
Precambrian Crystalline Rocks
Paleozoic through Early Mesozoic Sedimentary Units
Cretaceous Seaway Sedimentary Units
Laramide Sedimentary Units
Tertiary and Cretaceous Igneous Intrusions
Post-Laramide Volcanic Rocks and Sedimentary Units
Quaternary Alluvium and Glacial Deposits
Structural Geology
Structural Evolution of Park County
Post-Laramide and Neogene Tectonism
Evaporitic Tectonism in South Park
Primary Structural Features

Groundwater In Park County

Crystalline Rock Aquifers
Precambrian Crystalline Bedrock
Tertiary And Cretaceous Igneous Intrusions
Tertiary Volcanic Rocks
Sedimentary Bedrock Aquifers And Confining Units
Paleozoic And Early Mesozoic Hydrogeologic Units
Cretaceous Seaway Hydrogeologic Units
Laramide Hydrogeologic Units
Post-Laramide Sedimentary Units
Unconsolidated Quaternary Deposits
Groundwater Flow Conditions