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Temporal trends in water-quality constituent concentrations and annual loads of chemical constituents in Michigan watersheds, 1998–2013

Scientific Investigations Report 2017-5147
Prepared in cooperation with the Michigan Department of Environmental Quality
By: , , and 
https://doi.org/10.3133/sir20175147

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Abstract

In 1998, the Michigan Department of Environmental Quality and the U.S. Geological Survey began the Water Chemistry Monitoring Program for select streams in the State of Michigan. Objectives of this program were to provide assistance with (1) statewide water-quality assessments, (2) the National Pollutant Discharge Elimination System permitting process, and (3) water-resource management decisions. As part of this program, water-quality data collected from 1998 to 2013 were analyzed to identify potential trends for select constituents that were sampled. Sixteen water-quality constituents were analyzed at 32 stations throughout Michigan. Trend analysis on the various water-quality data was done using either the uncensored Seasonal Kendall test or through Tobit regression. In total, 79 trends were detected in the constituents analyzed for 32 river stations sampled for the study period—53 downward trends and 26 upward trends were detected. The most prevalent trend detected throughout the State was for ammonia, with 11 downward trends and 1 upward trend estimated.

In addition to trends, constituent loads were estimated for 31 stations from 2002 to 2013 for stations that were sampled 12 times per year. Loads were computed using the Autobeale load computation program, which used the Beale ratio estimator approach to estimate an annual load. Constituent loads were the largest in large watershed streams with the highest annual flows such as the Saginaw and Grand Rivers. Likewise, constituent loads were the smallest in smaller tributaries that were sampled as part of this program such as the Boardman and Thunder Bay Rivers.

Suggested Citation

Hoard, C.J., Fogarty, L.R., and Duris, J.W., 2018, Temporal trends in water-quality constituent concentrations and annual loads of chemical constituents in Michigan watersheds, 1998–2013: U.S. Geological Survey Scientific Investigations Report 2017–5147, 79 p., https://doi.org/10.3133/sir20175147.

ISSN: 2328-0328 (online)

ISSN: 2328-031X (print)

Study Area

Table of Contents

  • Abstract
  • Introduction
  • Approach
  • Water-Quality Trend Results
  • Constituent Load Results
  • Comparison of Upper and Lower Watershed Yields
  • Summary
  • References Cited
  • Appendixes 1–2
Publication type Report
Publication Subtype USGS Numbered Series
Title Temporal trends in water-quality constituent concentrations and annual loads of chemical constituents in Michigan watersheds, 1998–2013
Series title Scientific Investigations Report
Series number 2017-5147
DOI 10.3133/sir20175147
Year Published 2018
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Michigan Water Science Center
Description vi, 79 p.
Country United States
State Michigan
Online Only (Y/N) N
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