Douglas County Groundwater Study

OF-15-10 Geology and Groundwater Resources of Douglas County

Citation:

Barkmann, P. E., F. Scot Fitzgerald, L. A. Sebol, W. Curtiss, J. Moore Pike, Annette Moore, and B. Taylor. “OF-15-10 Geology and Groundwater Resources of Douglas County.” Geology and Groundwater. Open File Reports. Golden, CO: Colorado Geological Survey, 2015.

Douglas 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 can be found in many different geologic settings. This report 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 to be beneficial to more technical users.

Available for download:

Report text with figures
ArcGIS shape files and layers

Individual figures and plates

1. Regional Location Map of Douglas County.
2. Stratigraphic column showing: 2a – Quaternary through Lower Cretaceous, 2b – Jurassic through Precambrian.
3. Structural Features of Douglas County.
4. Type Geophysical Log, Fox Hills Sandstone through Dawson Arkose.

List of Plates

1. Geologic Map.
2. Cross-section A-A’.
3. Precambrian Crystalline Bedrock Extent Map.
4. Older Paleozoic Sedimentary Unit Extent Map.
5. Older Paleozoic Sedimentary Unit Depth Map.
6. Lyons-Fountain Aquifer Extent Map.
7. Lyons-Fountain Aquifer Depth Map.
8. Dakota Group Aquifer Extent Map.
9. Dakota Group Aquifer Depth Map.
10. Laramie-Fox Hills Aquifer Extent Map.
11. Laramie-Fox Hills Aquifer Depth Map.
12. D1 Lower Fan Extent Map.
13. D1 Lower Fan Depth Map.
14. D1 Middle Unit Extent Map.
15. D1 Middle Unit Depth Map.
16. D1 Upper Fan Extent Map.
17. D1 Upper Fan Depth Map.
18. Dawson Arkose Aquifer Extent Map.
19. Dawson Arkose Aquifer Depth Map.
20. Alluvial Aquifer and Bedrock Elevation Map.

GIS information

An ArcGIS-based map (mxd) hosted on ArcGIS.com 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 in the map hosted in ArcGIS.com are as follows:

  • When you first open this project you will notice in the left hand corner “Contents” and the name “DouglasCounty Aquifercomb Final Map 2015”, click on this heading and then click “Layers” heading.
  • 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.
  • Selecting the House button inside the map will take you back to the initial start state of the map, which is the boundary of Douglas County.
  • Well files have a Total Depth (TD) and Water Level (WL) in feet. A “0” label mean that the depth or water level data were not included in the DWR database.

Disclaimer: These data are intended for use at 1:50,000 scale and are checked for accuracy accordingly. 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

Introduction

Background and Purpose

General Geology Of Douglas County

Regional Setting
Major Rock Units and Stratigraphy
Precambrian Igneous and Metamorphic Rocks
Paleozoic Sedimentary Units
Mesozoic Sedimentary Units
Cretaceous and Tertiary Laramide Sedimentary Units
Post-Laramide Volcanic and Sedimentary Units
Quaternary Deposits
Structural Geology
Rampart Range Fault Zone
Front Range Uplift
Denver Basin
Other Structural Features

Groundwater In Douglas County

Fractured Crystalline Rock Aquifers
Precambrian Igneous Rocks
Precambrian Metamorphic Rocks
Sedimentary Bedrock Aquifers and Confining Units
Older Paleozoic Unit
Lyons-Fountain Aquifer
Triassic-Jurassic Unit
Dakota Group Aquifer
Cretaceous Marine Shale Unit
Laramie-Fox Hills Aquifer
Laramie Formation
Denver Basin Group Hydrogeologic Units
Post-Laramide Hydrogeologic Units
Alluvial Aquifers
Other Near-Surface Groundwater

References