Groundwater is simply water that occupies the pore spaces, crevices, or fractures within soil or rock. Some materials have a greater ability to store and transmit water than others. An aquifer is a groundwater reservoir composed of geologic units that are saturated with water and sufficiently permeable to yield water in a usable quantity from wells and springs. Sand and gravel deposits, sandstone, limestone, and fractured crystalline rocks are examples of geologic units that form aquifers. The USGS identifies seven principal aquifers or aquifer systems in Colorado: South Platte Aquifer, Arkansas Aquifer, High Plains Aquifer, San Luis Valley Aquifer System, Denver Basin Aquifer System, Piceance Creek Basin Aquifer, and the Leadville Limestone Aquifer of west-central Colorado.
Groundwater use in Colorado dates back to before the turn of the 20th century augmented by the advent of the deep-well turbine pump. Nineteen of Colorado’s 63 counties rely solely on this important water resource for potable supplies and domestic uses. Groundwater withdrawals by private wells and public water supply systems serve an estimated twenty percent of the state’s population. Agriculture is the largest user of groundwater, primarily for irrigation, however, it is also used to meet nearly all livestock and rural domestic water needs as well.
Sufficient water for a single household may be relatively easily obtained from wells in the bedrock aquifers, even the crystalline Precambrian rocks of the mountains. However, as households multiply, creating increased demands from many wells, a local aquifer with very limited storage that was sufficient for a few users, may be quickly depleted or polluted. Through wise water-management policies, protective regulations, and conservation activities, we can assure both the availability and the suitability of groundwater for future use.
The recently published ON-010 Colorado Groundwater Atlas has comprehensive information about every aspect of groundwater across the state.
Association of American State Geologists (AASG) – AASG Hydraulic Fracturing Statement — A position paper on “fracking” including its impact on water resources.
Colorado’s Decision Support System — A water management system developed by the Colorado Water Conservation Board (CWCB) and the Colorado Division of Water Resources (CDWR) for each of Colorado’s major water basins.
Colorado Division of Water Resources (CDWR) — Information related to the state’s groundwater resources, including administration, well permitting, well contractor licensing, and groundwater level reports.
Colorado Ground Water Commission — Information and resources related to groundwater resources in designated basins.
Colorado’s Water Plan — Comprehensive long-term plan for all facets of water use across the state.
Denver Basin Rules (DWR) — Well-permitting resources for the Denver Basin region.
EPA Groundwater & Drinking Water — Basic groundwater info, as water well information and data on quality standards for the United States.
EPA Information on Artificial Recharge (AR) and Aquifer Storage and Recovery (ASR) — Federal clearinghouse for AR and ASR regulation.
International Commission on Stratigraphy’s International Chronostratigraphic Chart — Detailed stratigraphic information.
Oregon State University Well Water Program “Understanding Groundwater” — Excellent educational resource on the basics of groundwater.
USGS Colorado Water Science Center’s Groundwater Information & Data — Information relating to Colorado’s groundwater supplies, including real-time monitoring data, data mapper, and general groundwater knowledge.
USGS Colorado Active Water Level Network — Interactive map/data resource with real-time and periodic data feeds on more than 400 wells and springs across the state.
USGS Groundwater Information — Information related to national groundwater resources and aquifers, including general background, as well as more detailed science on specific aquifers.
USGS Groundwater Watch — Clearinghouse for national groundwater data and statistics. Statewide and county data is also presented.
ON-OF-15-10 — Geology and Groundwater Resources of Douglas County, Colorado — County-based groundwater survey that addresses in detail all aquifers utilized in each county including those in alluvial, sedimentary, and crystalline formations.
ON-OF-15-11 — Geology and Groundwater Resources of Park County, Colorado — County-based groundwater survey that addresses in detail all aquifers utilized in each county including those in alluvial, sedimentary, and crystalline formations.
ON-OF-16-04 — Geology and Groundwater Resources of Chaffee County, Colorado — County-based groundwater survey that addresses in detail all aquifers utilized in each county including those in alluvial, sedimentary, and crystalline formations.
ON-OF-17-01 — Geology and Groundwater Resources of Mesa County, Colorado — County-based groundwater survey that addresses in detail all aquifers utilized in each county including those in alluvial, sedimentary, and crystalline formations.
ON-OF-18-12 — Geology and Groundwater Resources of Elbert County, Colorado — County-based groundwater survey that addresses in detail all aquifers utilized in each county including those in alluvial, sedimentary, and crystalline formations.
ON-010 — Colorado Groundwater Atlas — This web-based report, including many graphics and tables, explores the most current state of Colorado’s groundwater.
ON-010D — Colorado Groundwater Atlas (Data) – v20210304 — The most current (20 May 2020) downloadable GIS dataset, also includes a full set of high-resolution Figures and Tables from the Atlas.
ON-010M — Colorado Groundwater Atlas (Map) – v20210304 — Includes the full extent of GIS-based groundwater data currently available. This complex map is the GIS half of our new web-based Groundwater Atlas.
ON-010-02D — ON-010-02D Colorado Statewide Alluvial Aquifer (Data) — GIS dataset of alluvial deposits along streams and rivers throughout Colorado — deposits with the potential for forming alluvial aquifers in direct hydraulic connection with surface water.