In discussions with water managers throughout the state, Mr. Tom Cech of the Central Colorado Water Conservancy District promoted the compilation of a ground-water atlas as a tool for water management district planners and as an educational resource for water users, legislators, and the public. The benefits of such a compendium were realized by Mr. Dan McAuliffe of the Colorado Water Conservation Board ( who solicited the Colorado Geological Survey (CGS) to create an atlas of Colorado’s ground-water resources. After consultation with the Colorado Division of Water Resources/State Engineer’s Office, the Colorado Ground-Water Association, and other vested private and public organizations, it was clear that a map-based atlas of Colorado’s ground-water resources would be beneficial to many decision-makers, planners, developers, ground-water professionals, and the public. Utilizing funds from the Colorado Department of Natural Resources Severance Tax Operational Fund, the Colorado Water Conservation Board authorized implementation of this project in 2001.

The Ground Water Atlas of Colorado is intended to be a comprehensive reference of the state’s ground-water resources: summarizing the location, geography, geology, water quality and hydrologic characteristics of its major aquifers. The information presented herein was collected, compiled, and analyzed by hydrogeologists within the Colorado Geological Survey. The atlas draws heavily on the well permit database established and maintained by the Colorado Division of Water Resources. The atlas also draws on the research of other scientists, especially the work of the U.S. Geological Survey. The information is presented in a graphical format supported by descriptive narratives and tables to better facilitate the reader's understanding of the material. Chapters 1 through 3 provide an introduction to ground water and its geological, hydrological, and legal context. These chapters lay a foundation on which to build an understanding of the state’s ground-water resources. Specific discussions of the hydrologic characteristics of the major aquifers and aquifer systems in Colorado are presented in Chapters 4 through 7. A glossary is included as Appendix A to aid the reader’s understanding of specific water terminology used in this publication.

This atlas is intended to benefit the community of policy-makers, water managers, and their respective technical staffs in making difficult decisions concerning ground water. The general public and ground-water professionals will also find this publication educational and beneficial. The information, maps, and tables in the atlas portray general, regional conditions. Local hydrogeologic conditions vary significantly, especially given Colorado’s complex geology and varied geography. A knowledgeable hydrogeologist or ground-water professional should be consulted for information or decisions on site-specific conditions.

This internet version of the Ground Water Atlas of Colorado contains only a portion of the content of the published book, essentially summarizing the primary points of each section and excluding some of the more technical information. Many references were used to compile the information contained in the Atlas. We have chosen to not include citations of references in this internet version of the Atlas for the sake of readability. The citations and references are available in the comprehensive published book, available from CGS. It can be ordered through the online bookstore

Matthew A. Sares
Chief, Environmental Geology Section

Vincent Matthews
Division Director and State Geologist