Water clarity of the Colorado River—Implications for food webs and fish communities

Fact Sheet 2016-3053
By: , and 



The closure of Glen Canyon Dam in 1963 resulted in drastic changes to water clarity, temperature, and flow of the Colorado River in Glen, Marble, and Grand Canyons. The Colorado River is now much clearer, water temperature is less variable throughout the year, and the river is much colder in the summer months. The flow—regulated by the dam—is now less variable annually, but has larger daily fluctuations than during pre-dam times. All of these changes have resulted in a different fish community and different food resources for fish than existed before the dam was built. Recent monitoring of water clarity, by measuring turbidity, has helped scientists and river managers understand modern water-clarity patterns in the dam-regulated Colorado River. These data were then used to estimate pre-dam turbidity in the Colorado River in order to make comparisons of pre-dam and dam-regulated conditions, which are useful for assessing biological changes in the river over time. Prior to dam construction, the large sediment load resulted in low water clarity almost all of the time, a condition which was more favorable for the native fish community.

Suggested Citation

Voichick, N., Kennedy, T.A., Topping, D.J., Griffiths, R.E., and Fry, K.L., 2016, Water clarity of the Colorado River—Implications for food webs and fish communities: U.S. Geological Survey Fact Sheet 2016–5053, 4 p., http://dx.doi.org/10.3133/fs20163053.

ISSN: 2327-6932 (online)

Study Area

Table of Contents

  • Water Clarity in Grand Canyon
  • Comparing Pre-Dam and Dam-Regulated Water Clarity
  • Measuring Water Clarity
  • Water Clarity, Temperature, and Biology
  • References Cited

Additional publication details

Publication type Report
Publication Subtype USGS Numbered Series
Title Water clarity of the Colorado River—Implications for food webs and fish communities
Series title Fact Sheet
Series number 2016-3053
DOI 10.3133/fs20163053
Year Published 2016
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Southwest Biological Science Center
Description 4 p.
Country United States
State Arizona, California, Colorado, Nevada Utah, New Mexico
Other Geospatial Colorado River basin
Online Only (Y/N) Y
Google Analytic Metrics Metrics page
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