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Scientific Investigations Report 2010–5029

Prepared in cooperation with the U.S. Environmental Protection Agency, Great Lakes National Program Office

Concentrations and Estimated Loads of Nutrients, Mercury, and Polychlorinated Biphenyls in Selected Tributaries to Lake Michigan, 2005–6

By Stephen M. Westenbroek

Abstract

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The Lake Michigan Mass Balance Project (LMMBP) measured and modeled the concentrations of environmentally persistent contaminants in air, river and lake water, sediment, and fish and bird tissues in and around Lake Michigan for an 18-month period spanning 1994–95. Tributary loads were calculated as part of the LMMBP. The work described in this report was designed to provide updated concentration data and load estimates for 5 nutrients, total mercury, and total polychlorinated biphenyl (PCB) at 5 of the original 11 LMMBP sampling sites.

Samples were collected at five Lake Michigan tributary monitoring sites during 2005 and 2006. Annual loads calculated for the 2005–6 sampling period are as much as 50 percent lower relative to the 1994–95 time period. Differences between the loads calculated for the two time periods are likely related to a combination of (1) biases introduced by a reduced level of sampling effort, (2) differences in hydrological characteristics, and (3) actual environmental change.

Estimated annual total mercury loads during 2005–6 ranged from 51 kilograms per year (kg/yr) in the Fox River to 2.2 kg/yr in the Indiana Harbor and Ship Canal. Estimated annual total PCB loads during 2005–6 ranged from 132 kg/yr in the Fox River to 6.2 kg/yr in the Grand River.

Posted August 5, 2010

For additional information contact:
Director, Wisconsin Water
   Science Center
U.S. Geological Survey
8505 Research Way
Middleton, WI 53562
http://wi.water.usgs.gov/

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Suggested citation:

Westenbroek, S.M., 2010, Concentrations and estimated loads of nutrients, mercury, and polychlorinated biphenyls in selected tributaries to Lake Michigan, 2005–6: U.S. Geological Survey Scientific Investigations Report 2010–5029, 73 p.



Contents

Acknowledgments

Abstract

Introduction

Study Design and Methods

Estimated Loads of Nutrients, Mercury, and Polychlorinated Biphenyls

Treatment Efficiency of the Stormwater-Filtration Device

Summary and Conclusions

References Cited

Appendix 1.  Analytical Methods

Appendix 2.  Quality-Control Data Tables

Appendix 3.  Data Tables

Appendix 4.  Concentrations of Ammonia Nitrogen and Total Kjeldahl Nitrogen at Five Lake Michigan Tributary Monitoring Sites

Appendix 5.  Calculated Loads

Appendix 6.  Description of Beale Load Calculation and Jackknifing Procedure

Appendix 7.  Regression Model Details



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