A Decision Framework For Managing The Spirit Lake And Toutle River System At Mount St Helens

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.

With a long history and deep connection to the Earth’s resources, indigenous peoples have an intimate understanding and ability to observe the impacts linked to climate change. Traditional ecological knowledge and tribal experience play a key role in developing future scientific solutions for adaptation to the impacts. The book explores climate-related issues for indigenous communities in the United States, including loss of traditional knowledge, forests and ecosystems, food security and traditional foods, as well as water, Arctic sea ice loss, permafrost thaw and relocation. The book also highlights how tribal communities and programs are responding to the changing environments. Fifty authors from tribal communities, academia, government agencies and NGOs contributed to the book. Previously published in Climatic Change, Volume 120, Issue 3, 2013.

In the last one hundred years, a number of catastrophic events associated with rockslide dam formation and failure have occurred in the mountain regions of the world. This book presents a global view of the formation, characteristics and behaviour of natural and artificial rockslide dams. Chapters include a comprehensive state-of-the-art review of our global understanding natural and artificial rockslide dams, overviews of approaches to rockslide dam risk mitigation, regional studies of rockslide dams in India, Nepal, China, Pakistan, New Zealand, and Argentina. Rockslide dams associated with large-scale instability of volcanoes are also examined. Detailed case histories of well-known historic and prehistoric rockslide dams provide examples of investigations of rockslide dam behaviour, stability, and characteristics. The formation and behaviour of rockslide-dammed lakes ("Quake Lakes") formed during the 2008 Wenchuan Earthquake, China are also comprehensively summarised. The formation, sedimentology and stability of rockslide dams is examined in several analytical papers. An analysis of break-out floods from volcanogenic lakes and hydrological methods of estimating break-out flood magnitude and behavior are reviewed. The use of remote sensing data in rockslide-dammed lake characterisation is explored and a new approach to the classification of rockslide dams is introduced. Finally, a unique section of the book summarises Russian and Kyrgyz experience with blast-fill dam construction in two papers by leading authorities on the technology. The volume contains 24 papers by 50 authors from 16 countries including most of the recognised world authorities on the subject.

The 1980 eruption of Mount St. Helens caused tragic loss of life and property, but also created a unique opportunity to study a huge disturbance of natural systems and their subsequent responses. This book synthesizes 25 years of ecological research into of volcanic activity, and shows what actually happens when a volcano erupts, what the immediate and long-term dangers are, and how life reasserts itself in the environment.