The Future of Water Quality in
Coeur d’Alene Lake
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Committee on the Future of Water Quality in Coeur d’Alene Lake
Water Science and Technology Board
Division on Earth and Life Studies
Consensus Study Report
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This activity was supported by contracts between the National Academy of Sciences and the Idaho Department of Environmental Quality, Kootenai County, and the U.S. Environmental Protection Agency. Any opinions, findings, conclusions, or recommendations expressed in this publication do not necessarily reflect the views of any organization or agency that provided support for the project.
International Standard Book Number-13: 978-0-309-69041-6
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Digital Object Identifier: https://doi.org/10.17226/26620
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Suggested citation: National Academies of Sciences, Engineering, and Medicine. 2022. The Future of Water Quality in Coeur d’Alene Lake. Washington, DC: The National Academies Press. https://doi.org/10.17226/26620.
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COMMITTEE ON THE FUTURE OF WATER QUALITY IN COEUR D’ALENE LAKE
SAMUEL N. LUOMA (Chair), Institute of the Environment, University of California, Davis
ROBERT L. ANNEAR, Geosyntec Consultants, Portland, OR
WILLIAM A. ARNOLD, University of Minnesota, St. Paul
MICHAEL T. BRETT, University of Washington, Seattle
JAMES J. ELSER (NAS), Flathead Lake Biological Station, University of Montana, Polson
SCOTT E. FENDORF, Stanford University, Stanford, CA
ALEJANDRO N. FLORES, Boise State University, Idaho
PRIYA M. GANGULI, California State University, Northridge*
ROBERT M. HIRSCH, U.S. Geological Survey (retired), Reston, VA
LYNN E. KATZ, University of Texas, Austin
JAMES G. MOBERLY, University of Idaho, Moscow
S. GEOFFREY SCHLADOW, Tahoe Environmental Research Center and University of California, Davis
National Academies of Sciences, Engineering, and Medicine Staff
LAURA J. EHLERS, Senior Program Officer, Water Science and Technology Board
RACHEL SILVERN, Program Officer, Board on Atmospheric Sciences and Climate
CALLA ROSENFELD, Senior Program Assistant, Water Science and Technology Board
ERIC EDKIN, Manager of Internal Communications and Program Support, Division on Earth and Life Studies
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* Resigned from the committee in May 2022.
WATER SCIENCE AND TECHNOLOGY BOARD
CATHERINE L. KLING (NAS) (Chair), Cornell University, Ithaca, NY
NEWSHA AJAMI, Lawrence Berkeley National Laboratory, Berkeley, CA
PEDRO J. ALVAREZ (NAE), Rice University, Houston, TX
JONATHAN D. ARTHUR, American Geosciences Institute, Washington, DC
RUTH L. BERKELMAN (NAM), Emory University, Atlanta, GA
JORDAN R. FISCHBACH, The Water Institute of the Gulf, Pittsburgh, PA
ELLEN GILINSKY, Ellen Gilinsky, LLC, Seattle, WA
ROBERT M. HIRSCH, U.S. Geological Survey (retired), Reston, VA
VENKATARAMAN LAKSHMI, University of Virginia, Charlottesville
MARK W. LECHEVALLIER, Dr. Water Consulting, LLC, Morrison, CO
CAMILLE PANNU, Columbia University, New York, NY
DAVID L. SEDLAK (NAE), University of California, Berkeley
JENNIFER TANK, University of Notre Dame, Notre Dame, IN
DAVID WEGNER, Woolpert Engineering, Tucson, AZ
Water Science and Technology Board Staff
DEBORAH GLICKSON, Board Director
LAURA EHLERS, Senior Program Officer
STEPHANIE JOHNSON, Senior Program Officer
CHARLES BURGIS, Associate Program Officer
MARGO REGIER, Associate Program Officer
JONATHAN TUCKER, Associate Program Officer
JEANNE AQUILINO, Finance Business Partner
EMILY BERMUDEZ, Program Assistant
PADRAIGH HARDIN, Program Assistant
MILES LANSING, Program Assistant
OSHANE ORR, Program Assistant
Preface
Coeur d’Alene Lake (or the Lake) in northern Idaho is an invaluable recreational, economic, and natural resource asset for residents of Idaho, eastern Washington, and the nation. The issues that confront the Lake today reflect the history of other water bodies in the western United States. As the United States expanded westward, during the era of “manifest destiny,” what were once tribal homelands were confiscated across the west. In this case, it left the Coeur d’Alene Tribe with a fraction of its original homeland, including only the southern part of Coeur d’Alene Lake and remnants of what was once its breadbasket in the north. Although more recent agreements have granted some lands back to the Coeur d’Alene Tribe, those include wetlands and inshore areas so contaminated with lead and arsenic that the Tribal Authority has had to ban traditional practices like harvesting water potatoes in those parts of the northern Lake.
When the mineral extraction boom began in the western United States in the last half of the 1800s, usually after discoveries of gold, the Coeur d’Alene basin was one of the centers of activity. Mining, milling, and smelting dominated the valley from 1880 through the 1960s over a large area 60 kilometers upstream from the Lake. Like elsewhere in the west, great riches were extracted from mineral deposits in the basin (dominated in this case by extraction of lead and silver). What was left behind seemed like a moonscape1 of unvegetated floodplain soils and mountainsides: lands so contaminated that little vegetation could grow. Riverbanks and riverbed sediments were heavily contaminated with lead, zinc, arsenic, and cadmium from wastes released directly to the South Fork of the Coeur d’Alene River, and barren mountainsides reflected the atmospheric fallout from smelter operations. Contaminated runoff made its first detectable impact on the sediments of Coeur d’Alene Lake around 1900. Contaminated waters and sediments continue to be deposited in the Lake today, reflecting the legacy of nearly 100 years of mineral extraction.
In 1983, the U.S. Environmental Protection Agency (EPA) listed the Bunker Hill Mining and Metallurgical Complex in northern Idaho as a Superfund site on the National Priorities List and remediation activities began shortly thereafter. In 1998, EPA began applying Superfund requirements beyond the original Bunker Hill boundaries to areas throughout the 1,500-square mile Coeur d’Alene River basin project area but did not select a remedy to address Coeur d’Alene Lake.
The latest phase in the development of the west includes increased population growth in the more rural communities, especially exceptionally scenic areas such as Coeur d’Alene Lake. In 2021, the Wall Street Journal
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1 My personal observation from visits to the region in the 1970s and 1980s.
declared that Coeur d’Alene represented the “hottest” real estate market in America. With population growth came concern about nutrient inputs and eutrophication that, in other water bodies, have resulted in a loss of ecosystem services critical to development, including loss of lake clarity, eutrophication, nuisance algal blooms, and loss of native fisheries. In 2002, EPA began plans for remedial actions to address mine waste contamination in the lower basin of the Coeur d’Alene River up to the Lake. But rather than select a remedy for the Lake itself, EPA agreed to have the state of Idaho and the Coeur d’Alene Tribe develop and implement a Lake Management Plan (LMP) outside of the Superfund process. The LMP was published in 2009. The goal of the plan was to manage nutrient loads entering the basin in an effort to sustain adequate oxygen levels in the Lake’s water column and minimize the potential for metals mobilization.
The issues of concern today represent the nexus of the issues that developed over this history. More than two decades of scientific studies of the Coeur d’Alene basin have built a body of data useful to evaluating the intersection of these issues. But geographic differences in jurisdictions appear to be one factor limiting collaborative syntheses of these studies. EPA-sponsored studies and ongoing U.S. Geological Survey (USGS) stream monitoring are concentrated in the watershed. The Tribal Authority conducts monitoring and special studies, mostly in the Lake south of the confluence of the Coeur d’Alene River. The Idaho Department of Environmental Quality (IDEQ) conducts monitoring and studies north of the confluence. Monitoring data are publicly available, data reports describing trends were joint authored by the Tribal Authority and the IDEQ until recently, and an impressive array of process studies were published by USGS and academia over a 10-year period (1995–2005) but have continued at a much slower pace since then.
Nevertheless, concerns remain about questions critical to the future of the Lake. Part of the concern appears to stem from differences in interpretations of the existing data, perhaps influenced by collisions among the interests of different constituencies (not surprising in a situation where the problem is complicated and the stakes are high). Thus, critical questions remain. Is remediation of the damage from mineral extraction in the upstream landscape benefitting the Lake? Are nutrient inputs from increasing development and urbanization affecting lake clarity, and will they ultimately result in eutrophication? Are there interactions between declining metal inputs to the Lake, as remediation proceeds, and the types of lake productivity that affect clarity and other signs of eutrophication? Can the native fisheries and wetland resources that once provided the Tribe’s breadbasket and traditional practices be recovered? Hence, the request was made to the National Academies of Sciences, Engineering, and Medicine to establish an ad hoc consensus committee to analyze available data and information about Coeur d’Alene Lake water quality and provide recommendations to address identified issues of concern.2
The study was commissioned specifically to evaluate the future of water quality in Coeur d’Alene Lake by three of the parties with closest connections to the well-being of the Lake: the IDEQ, EPA, and Kootenai County, Idaho. The remit was restricted to analyses relevant to the status and future of the Lake. The committee appointed by the National Academies began its task in January 2021, in the middle of the COVID-19 pandemic. The pandemic limited travel throughout the study period and forced the committee to meet virtually for five of its six meetings—an unprecedented approach for such panels. Although the committee was unable to visit the Lake as a group, we were aided greatly by a virtual course from the University of Idaho on the history of the Coeur d’Alene Tribe and a virtual film tour of key sites in the valley put together by Jamie Brunner of IDEQ and Ed Moreen of the EPA. The Coeur d’Alene Tribe, IDEQ, EPA, and USGS went out of their way, over and over, to find the data and reports we needed for the investigation. Our efforts included reviews of the relevant literature, analyses of raw data provided as above, and statistical analysis of trends. Details of analytical methods are presented in the report’s appendixes. This is an unusual report for the National Academies in that it includes original analysis and key conclusions that resulted from those analyses. In many cases, the conclusions stand alone and no recommendations were necessarily warranted.
The study was established under the auspices of the Water Science and Technology Board of the National Academies. The Committee on the Future of Water Quality in Coeur d’Alene Lake included 11 individuals whose joint expertise covered the diversity of disciplines relevant to the study. The committee heard from many local experts about ongoing water quality monitoring and modeling in Coeur d’Alene Lake, climate in the Coeur d’Alene
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2 The formal study statement of task is found in the Summary.
region, and updates on the Bunker Hill Superfund site. I would like to thank the following individuals for giving numerous informative presentations to the committee: Dan McCracken, Jamie Brunner, Craig Cooper, and Robert Steed, IDEQ; Ed Moreen, Cami Grandinetti, and Kim Prestbo, EPA; Dale Chess, Rebecca Stevens, and Phil Cernera, the Coeur d’Alene Tribe; Lauren Zinsser, Dan Wise, and Chris Mebane, USGS; Chris Fillios, County of Kootenai; Tyler Jantzen, Jacobs; Guillaume Mauger, University of Washington; and Erin Brooks, University of Idaho. The committee also thanks the many individuals who spoke during open-mic sessions or submitted written comments to the committee during the course of the study.
Samuel N. Luoma, Chair
Committee on the Future of Water Quality in Coeur d’Alene Lake
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Acknowledgments
This Consensus Study was reviewed in draft form by individuals chosen for their diverse perspectives and technical expertise. The purpose of this independent review is to provide candid and critical comments that will assist the National Academies of Sciences, Engineering, and Medicine in making each published report as sound as possible and to ensure that it meets the institutional standards for quality, objectivity, evidence, and responsiveness to the charge. The review comments and draft manuscript remain confidential to protect the integrity of the process.
We thank the following individuals for their review of this proceedings:
James B. Cotner, University of Minnesota
Joseph L. Domagalski, USGS Sacramento
James N. Galloway (NAS), University of Virginia
Matthew Ginder-Vogel, University of Wisconsin
K. David Hambright, University of Oklahoma
Dennis P. Lettenmaier (NAE), University of California at Los Angeles
Ann S. Maest, Buka Environmental
Jerome O. Nriagu, University of Michigan
Kimberly J. Van Meter, Pennsylvania State University.
Although the reviewers have provided many constructive comments and suggestions, they were not asked to endorse the conclusions or recommendations nor did they see the final draft of the report before its release. The review of this report was overseen by Joan B. Rose (NAE), Michigan State University, and Richard G. Luthy (NAE), Stanford University. Appointed by the National Academies, they were responsible for making certain that an independent examination of this report was carried out in accordance with institutional procedures and that all review comments were carefully considered. Responsibility for the final content of this report rests entirely with the authoring Committee and the institution.
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Contents
Introduction to the CDA Region
Mining History and the Superfund Site
Federal, Regional, and Local Authority and Oversight
Current Water Quality Conditions
2 LONG-TERM MONITORING OF COEUR D’ALENE LAKE AND ITS WATERSHED
Published Summaries of Long-Term Monitoring Data
3 ANALYSIS OF INPUTS TO COEUR D’ALENE LAKE
Sources of Metal Input to Coeur d’Alene Lake
The Superfund Remedy and Its Effects on Metal Inputs
Sources of Phosphorus to Coeur d’Alene Lake
Analysis of Inputs to Coeur d’Alene Lake
Conclusions and Recommendations
4 IN-LAKE PROCESSES: HYDRODYNAMICS
Reservoir Modeling of Coeur d’Alene Lake
Conclusions and Recommendations
5 IN-LAKE PROCESSES: DISSOLVED OXYGEN AND NUTRIENTS
Eutrophication, Productivity, and Oxygen Depletion
Analyses of Dissolved Oxygen Trends
Conclusions and Recommendations
In-Lake Processes Relevant to Metals
Analysis of Trends in Dissolved Zinc
Analysis of Trends in Dissolved Cadmium
Analysis of Trends in Total Lead
Conclusions and Recommendations
Introduction to Biogeochemical Processes in Lake Sediments
Metal(loid) Dynamics Within CDA Lake Sediments
Key Issues About Sediment Processes Under Changing Conditions
Conclusions and Recommendations
8 GAPS IN LAKE AND WATERSHED MONITORING
Improvements to River Monitoring
Improvements to Lake Monitoring
Conclusions and Recommendations
9 RISKS OF METALS CONTAMINATION IN COEUR D’ALENE LAKE
Conclusions and Recommendations
10 FUTURE WATER QUALITY CONSIDERATIONS
Will Climate Change, Population Growth, and Land Use Reverse Water Quality Trends in CDA Lake?
Future Water Quality Scenarios