Using Regional Watershed Data to Assess Water-Quality Impairment in the Pacific Drainages of the United States

Scientific Investigations Report 2021-5087
National Water Quality Program



Two datasets containing the first complete estimates of reach-scale nutrient, water use, dissolved oxygen, and pH conditions for the Pacific drainages of the United States were created to help inform water-quality management decisions in that region. The datasets were developed using easily obtainable watershed data, most of which have not been available until recently, and the techniques that were used provide a framework for integrating watershed data to assess water-quality impairment across other large hydrologic regions in the United States. These datasets were used to summarize regional nutrient and water-use conditions within impaired water bodies and to summarize regional dissolved oxygen concentrations and pH conditions for free-flowing stream reaches. Two examples are also presented that show how the datasets can be applied to specific water-quality management issues: (1) nutrient conditions in water bodies that have recently experienced problems with harmful algal blooms; and (2) dissolved oxygen and pH conditions in stream reaches likely to be populated by steelhead trout (Oncorhynchus mykiss irideus) during their summer run. The nutrient and water-use estimates could help inform actions aimed at managing water-quality conditions in impaired water bodies while the dissolved oxygen and pH predictions could be useful as screening tools to identify water bodies experiencing potential impairment.

Suggested Citation

Wise, D.R., 2021, Using regional watershed data to assess water-quality impairment in the Pacific Drainages of the United States: U.S. Geological Survey Scientific Investigations Report 2021–5087, 29 p.,

ISSN: 2328-0328 (online)

Study Area

Table of Contents

  • Acknowledgments
  • Abstract
  • Introduction
  • Methods
  • Results
  • Water-Quality Management Applications
  • Discussion
  • Conclusions
  • References Cited
Publication type Report
Publication Subtype USGS Numbered Series
Title Using regional watershed data to assess water-quality impairment in the Pacific Drainages of the United States
Series title Scientific Investigations Report
Series number 2021-5087
DOI 10.3133/sir20215087
Year Published 2021
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Oregon Water Science Center
Description vii, 29 p.
Country United States
State California, Idaho, Montana, Nevada, Oregon, Utah, Washington, Wyoming
Online Only (Y/N) Y
Google Analytic Metrics Metrics page
Additional publication details