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Groundwater-Level Elevations in the Bedrock Aquifers of the Denver Basin Aquifer System, Elbert County, Colorado, 2015–23

Scientific Investigations Report 2026-5115
Prepared in cooperation with the Elbert County Board of County Commissioners
By: , , and 
https://doi.org/10.3133/sir20265115

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Abstract

Water users in Elbert County, Colorado, rely on groundwater from bedrock aquifers in the Denver Basin aquifer system (upper Dawson, lower Dawson, Denver, Arapahoe, and Laramie-Fox Hills aquifers) for approximately half of their water uses. Withdrawals from the bedrocks aquifers have increased to meet the water use needs of expanding regional population growth and development. The U.S. Geological Survey, in cooperation with the Elbert County Board of County Commissioners, began a study in 2015 to monitor groundwater levels within Elbert County. The primary purpose of this report is to present a summary of groundwater levels measured during the study period (2015–23) and present results from statistical analyses of changes in groundwater-level elevations through time.

Discrete groundwater levels were measured at 36 wells within Elbert County. Seven of those wells contained equipment to make and record continuous groundwater-level measurements at hourly intervals. All aquifers, except the lower Dawson aquifer, had only declining groundwater-level elevations in discrete measurements for wells with statistically significant trends. Of the eight statistically significant trends in the lower Dawson aquifer, two wells indicated increasing groundwater-level elevation from discrete measurements. The groundwater-level elevation trend medians in the upper Dawson, lower Dawson, Denver, Arapahoe, and Laramie-Fox Hills aquifers were −0.23, −0.66, −0.64, −0.39, and −0.63 feet per year, respectively, for discrete groundwater-level elevation measurements. Trends in continuous groundwater-level elevations were in agreement with statistically significant trends in discrete groundwater-level elevations for all wells. The groundwater-level elevation trend medians in this study, compared to the overall trends in a 2015−2018 study, both indicated declining groundwater-level elevations except in the upper Dawson aquifer, where the trend direction was opposite, a positive trend from 2015 to 2018 and a negative trend (declining groundwater elevations) from 2015 to 2023. The change in trends within the upper Dawson aquifer may be affected by differences in the study period and the trend analysis applied. Trends during the 2015–23 study period were compared to departures from the median 2015 groundwater-level elevation for each site in each aquifer. In general, the departures from the 2015 median supported trends observed at each site and correlated spatially with greater departures near the western border of Elbert County. Additionally, 30-year precipitation data showing wet and dry periods were overlaid with the departure from the 2015 median to assess groundwater-level patterns in wells in the five aquifers. Departures from the 2015 median groundwater-level elevations appeared greatest during the dry period between 2020 and 2023. Potentiometric-surface maps of the upper and lower Dawson aquifers created from static April 2023 groundwater elevations indicated groundwater-flow direction is generally from the south to the north. Results of this study could be used to guide additional groundwater monitoring in Elbert County and could aid in long-term planning of water resources.

Suggested Citation

Palko, K.M., Russell, C.A., and Pieseski, N.J., 2026, Groundwater-level elevations in the bedrock aquifers of the Denver Basin aquifer system, Elbert County, Colorado, 2015–23: U.S. Geological Survey Scientific Investigations Report 2026–5115, 41 p., https://doi.org/10.3133/sir20265115.

ISSN: 2328-0328 (online)

Study Area

Table of Contents

  • Acknowledgments
  • Abstract
  • Introduction
  • Study Methods
  • Groundwater-Level Elevations in the Denver Basin Bedrock Aquifers of Elbert County
  • Potential Additional Work
  • Summary
  • References Cited
  • Appendix 1. Groundwater-Well Measurement Diagram
  • Appendix 2. Hydrographs Showing Groundwater-Level Elevation Through Time for Wells in Elbert County Groundwater-Level Monitoring Network
  • Appendix 3. Descriptions and Equations of Mann-Kendall Test, Seasonal Mann-Kendall Test, and Theil-Sen Slope Estimate
Publication type Report
Publication Subtype USGS Numbered Series
Title Groundwater-level elevations in the bedrock aquifers of the Denver Basin aquifer system, Elbert County, Colorado, 2015–23
Series title Scientific Investigations Report
Series number 2026-5115
DOI 10.3133/sir20265115
Publication Date January 29, 2026
Year Published 2026
Language English
Publisher U.S. Geological Survey
Publisher location Reston VA
Contributing office(s) Colorado Water Science Center
Description Report: vii, 41 p.; Database
Country United States
State Colorado
County Elbert County
Online Only (Y/N) Y
Additional publication details