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A Decision Framework for Managing the Spirit Lake and Toutle River System at Mount St THE NATIONAL ACADEMIES PRESS This PDF is available at http://nap.edu/24874 SHARE A Decision Framework for Managing the Spirit Lake and Toutle River System at Mount St. Helens (2018) DETAILS 336 pages | 6 x 9 | PAPERBACK ISBN 978-0-309-46444-4 | DOI 10.17226/24874 CONTRIBUTORS GET THIS BOOK 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; FIND RELATED TITLES Division of Behavioral and Social Sciences and Education; National Academies of Sciences, Engineering, and Medicine SUGGESTED CITATION National Academies of Sciences, Engineering, and Medicine 2018. A Decision Framework for Managing the Spirit Lake and Toutle River System at Mount St. Helens. Washington, DC: The National Academies Press. https://doi.org/10.17226/24874. Visit the National Academies Press at NAP.edu and login or register to get: – Access to free PDF downloads of thousands of scientific reports – 10% off the price of print titles – Email or social media notifications of new titles related to your interests – Special offers and discounts Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the National Academies Press. (Request Permission) Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved. 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 of Behavioral and Social Sciences and Education A Consensus Study Report of Copyright National Academy of Sciences. All rights reserved. A Decision Framework for Managing the Spirit Lake and Toutle River System at Mount St. Helens 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 recommenda- tions 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: 978-0-309-46444-4 International Standard Book Number-10: 0-309-46444-7 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 2018 by the National Academy of Sciences. All rights reserved. Printed in the United States of America Cover: Front image: Mount St. Helens, 100 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 feet was reduced to 8,363 feet. Spirit Lake, seen here, was raised approximately 200 feet 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, Mount St. Helens, and the 1980 blast zone, Spirit Lake, and in the distance, Mount 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. Copyright National Academy of Sciences. All rights reserved. A Decision Framework for Managing the Spirit Lake and Toutle River System at Mount St. Helens 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 technol- ogy. 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, objec- tive 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. Copyright National Academy of Sciences. All rights reserved. A Decision Framework for Managing the Spirit Lake and Toutle River System at Mount St. Helens Consensus Study Reports published by the National Academies of Sciences, Engineering, and Medicine document the evidence-based con- sensus on the study’s statement of task by an authoring committee of experts. Reports typically include findings, conclusions, and recommen- dations based on information gathered by the committee and committee deliberations. Each report has been subjected to a rigorous and indepen- dent 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. Copyright National Academy of Sciences. All rights reserved. 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 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 A. SHABMAN, Resources for the Future, Washington, District of Columbia National Academies of Sciences, Engineering, and Medicine Staff SAMMANTHA L. MAGSINO, Senior Program Officer PAUL STERN, Scholar* EDMOND DUNNE, Program Officer* COURTNEY R. DEVANE, Administrative Coordinator NICHOLAS D. ROGERS, Financial and Research Associate *Until June 2017. v Copyright National Academy of Sciences. All rights reserved. A Decision Framework for Managing the Spirit Lake and Toutle River System at Mount St. Helens Copyright National Academy of Sciences. All rights reserved. A Decision Framework for Managing the Spirit Lake and Toutle River System at Mount St. Helens Preface The 1980 eruption of Mount St. Helens resulted in a massive debris ava- lanche 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 a large part of 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
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