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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2017. A Decision Framework for Managing the Spirit Lake and Toutle River System at Mount St. Helens. Washington, DC: The National Academies Press. doi: 10.17226/24874.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2017. A Decision Framework for Managing the Spirit Lake and Toutle River System at Mount St. Helens. Washington, DC: The National Academies Press. doi: 10.17226/24874.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2017. A Decision Framework for Managing the Spirit Lake and Toutle River System at Mount St. Helens. Washington, DC: The National Academies Press. doi: 10.17226/24874.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2017. A Decision Framework for Managing the Spirit Lake and Toutle River System at Mount St. Helens. Washington, DC: The National Academies Press. doi: 10.17226/24874.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2017. A Decision Framework for Managing the Spirit Lake and Toutle River System at Mount St. Helens. Washington, DC: The National Academies Press. doi: 10.17226/24874.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2017. A Decision Framework for Managing the Spirit Lake and Toutle River System at Mount St. Helens. Washington, DC: The National Academies Press. doi: 10.17226/24874.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2017. A Decision Framework for Managing the Spirit Lake and Toutle River System at Mount St. Helens. Washington, DC: The National Academies Press. doi: 10.17226/24874.
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Page viii Cite
Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2017. A Decision Framework for Managing the Spirit Lake and Toutle River System at Mount St. Helens. Washington, DC: The National Academies Press. doi: 10.17226/24874.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2017. A Decision Framework for Managing the Spirit Lake and Toutle River System at Mount St. Helens. Washington, DC: The National Academies Press. doi: 10.17226/24874.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2017. A Decision Framework for Managing the Spirit Lake and Toutle River System at Mount St. Helens. Washington, DC: The National Academies Press. doi: 10.17226/24874.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2017. A Decision Framework for Managing the Spirit Lake and Toutle River System at Mount St. Helens. Washington, DC: The National Academies Press. doi: 10.17226/24874.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2017. A Decision Framework for Managing the Spirit Lake and Toutle River System at Mount St. Helens. Washington, DC: The National Academies Press. doi: 10.17226/24874.
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Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

A DECISION FRAMEWORK FOR MANAGING THE SPIRIT LAKE AND TOUTLE RIVER SYSTEM AT MOUNT ST. HELENS Committee on Long-Term Management of the Spirit Lake/Toutle River System in Southwest Washington Committee on Geological and Geotechnical Engineering Board on Earth Sciences and Resources Water Science and Technology Board Division on Earth and Life Studies Board on Environmental Change and Society Division on Behavioral and Social Sciences and Education A Consensus Study Report of PREPUBLICATION Subject to further editorial revision

THE NATIONAL ACADEMIES PRESS 500 Fifth Street, NW Washington, DC 20001 This activity is supported by the U.S. Department of Agriculture’s U.S. Forest Service under Grant No. 16-DG-11261952-008. 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: International Standard Book Number-10: Digital Object Identifier: https://doi.org/10.17226/24874 Additional copies of this publication are available for sale from the National Academies Press, 500 Fifth Street, NW, Keck 360, Washington, DC 20001; (800) 624-6242 or (202) 334-3313; http://www.nap.edu. Copyright 2017 by the National Academy of Sciences. All rights reserved. Printed in the United States of America Cover: Front image: Mt. St Helen’s, 96 miles south of Seattle, Washington, boasts the deadliest and most economically destructive volcanic explosion in U.S. history when it erupted on May 18, 1980. Its original height of 9,667' was reduced to 8,363'. Spirit Lake, seen here, was raised approximately 200' in the eruption. The image is courtesy of Barry Maas and his images are available at https://www.flickr.com/photos/bmaas/. The rear cover is courtesy of C. Scott Cameron of GeoLogical Consulting, LLC, and a member of the Board on Earth Sciences and Resources. View is looking east to the upper Toutle River valley, Mt. St. Helens, and the 1980 blast zone, Spirit Lake, and in the distance, Mt. Adams. Taken October 31, 2017.. Suggested citation: National Academies of Sciences, Engineering and Medicine. 2017. A Decision Framework for Managing the Spirit Lake and Toutle River System at Mount St. Helens. Washington, DC: The National Academies Press. doi: https://doi.org/10.17226/24874. PREPUBLICATION Subject to further editorial revision

The National Academy of Sciences was established in 1863 by an Act of Congress, signed by President Lincoln, as a private, nongovernmental institution to advise the nation on issues related to science and technology. Members are elected by their peers for outstanding contributions to research. Dr. Marcia McNutt is president. The National Academy of Engineering was established in 1964 under the charter of the National Academy of Sciences to bring the practices of engineering to advising the nation. Members are elected by their peers for extraordinary contributions to engineering. Dr. C. D. Mote, Jr., is president. The National Academy of Medicine (formerly the Institute of Medicine) was established in 1970 under the charter of the National Academy of Sciences to advise the nation on medical and health issues. Members are elected by their peers for distinguished contributions to medicine and health. Dr. Victor J. Dzau is president. The three Academies work together as the National Academies of Sciences, Engineering, and Medicine to provide independent, objective analysis and advice to the nation and conduct other activities to solve complex problems and inform public policy decisions. The National Academies also encourage education and research, recognize outstanding contributions to knowledge, and increase public understanding in matters of science, engineering, and medicine. Learn more about the National Academies of Sciences, Engineering, and Medicine at www.nationalacademies.org. PREPUBLICATION Subject to further editorial revision

Consensus Study Reports published by the National Academies of Sciences, Engineering, and Medicine document the evidence-based consensus on the study’s statement of task by an authoring committee of experts. Reports typically include findings, conclusions, and recommendations based on information gathered by the committee and committee deliberations. Each report has been subjected to a rigorous and independent peer review process and it represents the position of the National Academies on the statement of task. Proceedings published by the National Academies of Sciences, Engineering, and Medicine chronicle the presentations and discussions at a workshop, symposium, or other event convened by the National Academies. The statements and opinions contained in proceedings are those of the participants and not endorsed by other participants, the planning committee, or the National Academies. For information about other products and activities of the National Academies, please visit nationalacademies.org/whatwedo. PREPUBLICATION Subject to further editorial revision

COMMITTEE ON LONG-TERM MANAGEMENT OF THE SPIRIT LAKE/TOUTLE RIVER SYSTEM IN SOUTHWEST WASHINGTON GREGORY B. BAECHER, NAE (Chair), University of Maryland, College Park JOHN BOLAND, Johns Hopkins University, Baltimore, Maryland THOMAS DUNNE, NAS, University of California, Santa Barbara YOUSSEF HASHASH, University of Illinois at Urbana-Champaign JOHN KUPFER, University of South Carolina, Columbia NING LU, Colorado School of Mines, Golden BASIL STUMBORG, BC Hydro, Vancouver, British Columbia, Canada KATHLEEN TIERNEY, University of Colorado Boulder DESIREE TULLOS, Oregon State University, Corvallis GREG A. VALENTINE, University at Buffalo, The State University of New York COMMITTEE UNPAID CONSULTANT LEONARD SHABMAN, Resources for the Future, Washington, District of Columbia NATIONAL ACADEMIES OF SCIENCES, ENGINEERING, AND MEDICINE STAFF SAMMANTHA MAGSINO, Senior Program Officer PAUL STERN, Scholar* EDMOND DUNNE, Program Officer* COURTNEY GIBBS, Administrative Coordinator NICHOLAS ROGERS, Financial and Research Associate * Until June 2017. v PREPUBLICATION Subject to further editorial revision

Preface The 1980 eruption of Mount St. Helens resulted in a massive debris avalanche and pyroclastic flow into the Toutle River valley. This event caused sweeping changes to the hydrology of the Toutle River, and to the Cowlitz River into which the Toutle flows. The headwater of the Toutle River in Spirit Lake was blocked by volcanic debris hundreds of feet in depth, and the lake bottom itself was raised 200 feet. Catastrophic breaching of the blockage by high water in Spirit Lake could release more than 300,000 acre-feet of water and 2.4 billion cubic yards of sediment into the Toutle, Cowlitz, and Columbia Rivers, causing massive damage and loss of life. The U.S. Forest Service (USFS) is responsible for the region around and including Mount St. Helens and Spirit Lake. Following the eruption, several alternatives were considered for draining the lake and maintaining a safe water level. The solution chosen was to bore a tunnel through Harry’s Ridge into the Coldwater creek drainage and thus into Coldwater Lake. Now some 36 years later, that tunnel has undergone and is again in need of expensive repairs. While the tunnel is located on land managed by the USFS, it was constructed by the U.S. Army Corps of Engineers (USACE). Using funds provided by the USFS, USACE has inspected and repaired the tunnel since its construction. The U.S. Geological Survey (USGS) has responsibility for monitoring geologic activity in the region. The technical issues precipitated by the 1980 eruption include not only management of Spirit Lake and its drainage, but also of the massive volume of sediments resulting from the eruption. Those sediments continue to be transported down the North Fork Toutle River where they create hazards to the environment, flood risk, and navigation. In 1989, the USACE constructed a sediment retention structure (SRS) in the North Fork Toutle River to minimize sediment transport into the Toutle and Cowlitz Rivers by trapping that the sediment upstream of the SRS. Whereas the SRS provided a temporary solution for sediment management downstream, its existence and management affects other aspects of river management, for example, that of restoration of anadromous fish passage in the system and the protection of cultural and recreational resources. Today, a complex system of infrastructure exists to control water and sediment flow. This infrastructure is subject to multiple natural hazards including volcanic, seismic, and hydrologic, and is the responsibility of separate federal, state, and local agencies. The need for millions of dollars of repairs on the tunnel prompted members of Congress to request that the USFS, USACE, and USGS to develop a long-term plan to manage water levels. An ad hoc committee of the National Academies of Sciences, Engineering, and Medicine was ultimately convened at the request of the USFS to “recommend a framework for technical decision making related to long- term management of risks related to the Spirit Lake and Toutle River system in light of the different priorities of federal, tribal, state, relevant local authorities, and other entities.” The management of a system of this complexity requires a methodical framework suitable to the systems aspects of the problem and the uncertainties which attend it. Identifying such a framework has been the committee’s goal. The committee is grateful for the competence and efficiency of the National Academies staff assigned to this project. Complicated logistical arrangements were handled with ease and good humor by Nicholas Rogers, Financial and Research Associate, and Courtney Gibbs, Program Associate. Leonard A. Shabman, Resident Scholar
at Resources for the Future, served as an vii PREPUBLICATION Subject to further editorial revision

viii PREFACE unpaid consultant to the committee. Paul Stern, a National Academies Scholar contributed to the committee’s meetings and report, as did Edmond Dunne. We also would like to thank National Academies staff member David Policansky for providing comments on the draft report. The staff director for the project has been Sammantha Magsino, Senior Program Officer with the Board on Earth Sciences and Resources. Without her, this study would not have been successful. She has an ability to convert energetic discussion into consensus, miscellaneous prose into coherent text, and rambling discourse into a rational report. Gregory B. Baecher Chair PREPUBLICATION Subject to further editorial revision

Acknowledgments This Consensus Study Report 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 study charge. The review comments and draft manuscript remain confidential to protect the integrity of the deliberative process. We thank the following individuals for their review of this report: Shane J. Cronin, The University of Auckland and GNS Science Ltd., New Zealand Robin Gregory, Decision Research, Halfmoon Bay, British Columbia, Canada William Hansmire, NAE, WSP USA, Los Angeles, California James K. Mitchell, NAE/NAS, Virginia Polytechnic Institute and State University, Blacksburg Doug Plasencia, Moffatt & Nichol, Phoenix, Arizona Bob Royer, Gallatin Public Affairs, Seattle, Washington Jeff Rubin, Tualatin Valley Fire and Rescue, Tigard, Oregon Colin Thorne, University of Nottingham, Vancouver, Washington Thomas Yancey, Texas A&M University, College Station Although the reviewers listed above provided many constructive comments and suggestions, they were not asked to endorse the conclusions or recommendations of this report nor did they see the final draft before its release. The review of this report was overseen by John Christian, an Independent Consultant and Catherine Kling of Iowa State University. They were responsible for making certain that an independent examination of this report was carried out in accordance with the standards of the National Academies and that all review comments were carefully considered. Responsibility for the final content rests entirely with the authoring committee and the National Academies. The committee met four times over a six-month period: three times in Kelso, Washington, and a final meeting in Washington, DC. In the course of those meetings, the committee consulted with interested and affected parties including those from the private and public sectors. The committee would like to thank, in alphabetical order: Gene Crocker, Cowlitz Game and Anglers Club; Gregory Drew, Drew’s Grocery, Toutle; Joe Gardener, Cowlitz County Board of Commissioners; Ashley Helenberg, Port of Longview; Dave Howe, Regional Habitat Program, Washington Department of Fish and Wildlife; Claudia Hunter, Toutle Valley Community Association; Steve Ogden, Pacific-Cascade Region, Washington Department of Natural Resources; Nathan Reynolds, Natural Resources Department, Cowlitz Indian Tribe; Ernie Schnabler, Cowlitz County Emergency Management; Ray Yurkewycz, Mount St. Helens Institute. The committee also met with and heard presentations from representatives of local, state, and federal agencies. They included, alphabetically, from USACE Sean Askelson, Jeremy ix PREPUBLICATION Subject to further editorial revision

x ACKNOWLEDGMENTS Britton, Chris Budai, Angela Duren, Tim Kuhn, David Scofield, and Paul Sclafani; from USGS Jon Major, and from USFS Charlie Crisafulli, Gordon Grant, Tedd Huffman, Gina Owens, and Jim Peña. During its open session meetings, town hall discussions, and site visits in the region, the committee had the opportunity to interact and learn from numerous individuals from affected communities and various interest groups. Individuals also provided written feedback to the committee. Their voluntary engagement with the committee is an indication of the importance placed on the sound and responsive management of the Spirit Lake and Toutle River system. PREPUBLICATION Subject to further editorial revision

Contents SUMMARY ....................................................................................................................................1 1 INTRODUCTION............................................................................................................12 The Charge to the Committee ............................................................................................14 Committee Membership.....................................................................................................17 Institutional Setting ............................................................................................................17 Natural Hazards Affecting Region Management ...............................................................18 The Current Decision Landscape .......................................................................................19 Defining Terms in the Statement of Task ..........................................................................20 Committee Approach to Its Task .......................................................................................23 Report Organization ...........................................................................................................26 2 REGIONAL SETTING ...................................................................................................27 Geographic Setting.............................................................................................................27 Geologic Setting.................................................................................................................32 Groundwater Flow .............................................................................................................38 Ecological Setting ..............................................................................................................41 Hydraulic Infrastructure .....................................................................................................45 Socio-Demographic and Economic Setting .......................................................................50 How the Setting Affects System Risk Assessment and Long-Term Management ............52 3 INSTITUTIONAL SETTING: DEVELOPING A COMMON UNDERSTANDING54 Pre-Eruption (1980) Management Context: Spirit Lake and Mount St. Helens ................54 Land Ownership in the Broader Toutle River Valley Circa 1980 .....................................57 Post-Event Management Responses to the Eruption (1980-1989) ....................................57 Ongoing Management Setting (1990-Present)...................................................................63 Interested and Affected Parties ..........................................................................................73 A Common Understanding for System Management ........................................................78 4 NATURAL HAZARDS ...................................................................................................82 Meteorological Input and Chronic Flooding......................................................................83 Volcanic Hazards ...............................................................................................................87 Seismic Hazards .................................................................................................................90 Catastrophic Flooding and the Spirit Lake Debris Blockage.............................................93 Ongoing Monitoring ..........................................................................................................97 5 THE ENGINEERED LANDSCAPE ..............................................................................99 Spirit Lake Water Levels and Risk of Catastrophic Flooding ...........................................99 Managing Sediments ........................................................................................................111 Managing Chronic Flood Risk .........................................................................................115 Short- and Long-Term Management ...............................................................................118 Operational Risk ..............................................................................................................119 Integration Using Probabilistic Risk Analysis .................................................................121 xi PREPUBLICATION Subject to further editorial revision

xii CONTENTS Leveraging Resources and Expertise ...............................................................................124 6 CHOOSING A DECISION FRAMEWORK AND IDENTIFYING THE DECISION PROBLEM.................................................................................................126 Choosing a Decision Framework .....................................................................................129 The Decision Problem......................................................................................................130 7 IDENTIFYING DECISION OBJECTIVES AND ALTERNATIVES .....................142 The Objectives .................................................................................................................142 The Alternatives ...............................................................................................................150 8 DECISION CONSEQUENCES AND TRADEOFFS .................................................157 What Are the Consequences? ..........................................................................................157 What Are the Tradeoffs? ..................................................................................................163 Compatibility of a PrOACT-Like Process with Agency Processes .................................169 9 APPLYING THE DECISION FRAMEWORK..........................................................171 Changing Mindsets ..........................................................................................................172 System Thinking ..............................................................................................................174 First Steps.........................................................................................................................174 Implementing the Framework ..........................................................................................176 REFERENCES ...........................................................................................................................178 APPENDIXES A Biographical Sketches of Committee Members ..............................................................187 B Meeting Agendas .............................................................................................................191 C Board Rosters ...................................................................................................................198 D Congressional Request Letter ..........................................................................................201 PREPUBLICATION Subject to further editorial revision

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The 1980 eruption of Mount St. Helens in southwest Washington State radically changed the physical and socio-economic landscapes of the region. The eruption destroyed the summit of the volcano, sending large amounts of debris into the North Fork Toutle River, and blocking the sole means of drainage from Spirit Lake 4 miles north of Mount St. Helens. As a result of the blockage, rising lake levels could cause failure of the debris blockage, putting the downstream population of approximately 50,000 at risk of catastrophic flooding and mud flows. Further, continued transport of sediment to the river from volcanic debris deposits surrounding the mountain reduces the flood carrying capacity of downstream river channels and leaves the population vulnerable to chronic flooding.

The legacy of the 1980 eruption and the prospect of future volcanic, seismic, and flood events mean that risk management in the Spirit Lake Toutle River system will be challenging for decades to come. This report offers a decision framework to support the long-term management of risks related to the Spirit Lake and Toutle River system in light of the different regional economic, cultural, and social priorities, and the respective roles of federal, tribal, state, and local authorities, as well as other entities and groups in the region. It also considers the history and adequacy of characterization, monitoring, and management associated with the Spirit Lake debris blockage and outflow tunnel, other efforts to control transport of water and sediment from the 1980 and later eruptions, and suggests additional information needed to support implementation of the recommended decision framework.

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