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Applying U.S. Geological Survey Science to Understand Effects to Water Supply in the Upper Colorado River Basin

Fact Sheet 2025-3036
By:  and 
https://doi.org/10.3133/fs20253036

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Introduction

The Colorado River Basin is a vital source of water to more than 40 million people in the Western United States and Mexico, including in major cities like Denver, Las Vegas, Phoenix, Tucson, Los Angeles, and San Diego, and supports irrigation for about 16,000 square kilometers of agricultural land. Since 2000, the southwestern United States has been unusually dry due to low precipitation and warm air temperatures, contributing to extreme water level declines of the two large reservoirs on the Colorado River, Lake Mead and Lake Powell. In 2021, these reservoirs reached their lowest levels on record, resulting in unprecedented restrictions on water usage in the basin. As much as 90 percent of the annual runoff in the Colorado River Basin originates in areas upstream from Lake Powell (hereafter, these areas will be referred to collectively as the “Upper Basin”). Consequently, understanding the processes that can affect water supply in the Upper Basin could be crucial for supporting human, agricultural, and ecological needs across a large spatial scale.

The U.S. Geological Survey (USGS) does a wide variety of science in cooperation with resource managers, municipalities, tribes, and local, State, and Federal agencies to help improve understanding of processes, such as streamflow and water quality, potentially affecting water supply in the Upper Basin. This fact sheet describes three key potential factors affecting water supply in the Upper Basin—snow processes and water storage, wildfire and basin hydrology, and salinity concentrations and water quality—and highlights associated USGS research activities in the basin.

Plain Language Summary

The U.S. Geological Survey (USGS) cooperates with resource managers, municipalities, tribes, and local, State, and Federal agencies to help improve understanding of processes potentially affecting water supply in the Colorado River Basin. This fact sheet describes three key potential factors affecting water supply in the upper portion of the basin—snow processes and water storage, wildfire and basin hydrology, and salinity concentrations and water quality—and highlights associated USGS research activities in the basin. The Colorado River Basin is an important water source for more than 40 million people in the Western United States and Mexico, providing water to major cities and irrigating agricultural land. However, since 2000, the region has faced prolonged drought conditions, leading to record low levels in Lake Mead and Lake Powell and resulting in water usage restrictions. The USGS plays a key role in studying the Colorado River Basin water supply. Understanding the processes that can affect water supply in the upper portion of the basin could be crucial for supporting human, agricultural, and ecological needs across a large spatial scale.

Suggested Citation

Day, N.K., and Williams, C.A., 2025, Applying U.S. Geological Survey science to understand effects to water supply in the Upper Colorado River Basin: U.S. Geological Survey Fact Sheet 2025-3036, 4 p., https://doi.org/10.3133/fs20253036.

ISSN: 2327-6932 (online)

ISSN: 2327-6916 (print)

Study Area

Table of Contents

  • Plain Language Summary
  • Introduction
  • Snow Processes and Water Storage
  • Wildfire and Basin Hydrology
  • Salinity Concentrations and Water Quality
  • Summary
  • References Cited
Publication type Report
Publication Subtype USGS Numbered Series
Title Applying U.S. Geological Survey science to understand effects to water supply in the Upper Colorado River Basin
Series title Fact Sheet
Series number 2025-3036
DOI 10.3133/fs20253036
Publication Date August 05, 2025
Year Published 2025
Language English
Publisher U.S. Geological Survey
Publisher location Reston VA
Contributing office(s) Colorado Water Science Center
Description 4 p.
Country United States
State Arizona, Colorado, New Mexico, Utah, Wyoming
Other Geospatial Colorado River basin
Online Only (Y/N) N
Additional publication details