thumbnail

Summary of Selenium in the Lower Gunnison River Basin, Colorado—Information and Data Gaps

Circular 1559
Prepared in cooperation with the Colorado Water Conservation Board, the Bureau of Reclamation, the Colorado River Water Conservation District, the U.S. Fish and Wildlife Service, the Bureau of Land Management, and the Natural Resources Conservation Service
By: , , and 
https://doi.org/10.3133/cir1559

Links

Abstract

The Cretaceous Mancos Shale is a geologic source of selenium in the lower Gunnison River Basin. Natural weathering processes and human activity mobilize selenium from the Mancos Shale and derived materials, and surface water, groundwater, and sediment all affect the transport of selenium from source areas to receiving streams and biota. Selenium accumulates through the aquatic food chain, and its toxic effects can result in invertebrate mortality and mortality, decreased reproduction, and deformities to fish and birds. The Bureau of Reclamation, in cooperation with the State of Colorado and Gunnison River Basin water users, is implementing a Selenium Management Program to reduce selenium concentrations in the lower Gunnison River Basin of Colorado. Goals of the Selenium Management Program are to (1) achieve compliance with the State of Colorado chronic aquatic-life standard for dissolved selenium (4.6 micrograms per liter) in the Gunnison River near Grand Junction, Colorado; (2) sufficiently improve water-quality conditions to assist in the recovery of endangered species in the Gunnison and Colorado Rivers by reducing selenium concentrations; and (3) support continued water uses in the basin.

Many previous studies have contributed to the understanding of selenium in the environment; however, monitoring and research data gaps exist in the lower Gunnison River Basin. The purpose of this report is to summarize information regarding selenium in the lower Gunnison River Basin and describe strategies for scientific research and monitoring to potentially improve understanding of selenium sources; processes affecting the mobilization, transport, and fate of selenium; and the effects of selenium-mitigation projects in the lower Gunnison River Basin. Monitoring and research data gaps discussed in this report include geologic mapping and geochemical source characterization, long-term and ongoing monitoring of the surface-water and groundwater networks, developing and refining statistical models, characterizing selenium on suspended sediment, modeling selenium in the food web, evaluating best management practices, and more.

Suggested Citation

Gidley, R.G., Leib, K.J., and Williams, C.A., 2025, Summary of selenium in the lower Gunnison River Basin, Colorado—Information and data gaps: U.S. Geological Survey Circular 1559, 44 p., https://doi.org/10.3133/cir1559.

ISSN: 2330-5703 (online)

Study Area

Table of Contents

  • Abstract
  • Introduction
  • Study Area Description
  • Selenium Geochemistry
  • Conceptual Model of Selenium Occurrence in the Lower Gunnison River Basin
  • Monitoring and Research Data Gaps
  • Summary
  • References Cited
Publication type Report
Publication Subtype USGS Numbered Series
Title Summary of selenium in the lower Gunnison River Basin, Colorado—Information and data gaps
Series title Circular
Series number 1559
DOI 10.3133/cir1559
Publication Date September 12, 2025
Year Published 2025
Language English
Publisher U.S. Geological Survey
Publisher location Reston VA
Contributing office(s) Colorado Water Science Center
Description vi, 44 p.
Country United States
State Colorado
Other Geospatial Lower Gunnison River basin
Online Only (Y/N) Y
Additional publication details