Mount Saint Helens

Scope of Work

This project completed work on the original design and construction of an upstream and downstream fish passable, sediment collection structure made of natural and man-made materials.  No structure like this exists in the world. The original design was completed between our owner, Stephen Eagar, PE, and Tim Abbe, Ph.D., PE.

Coordination for this project involved meetings and permission from members of Congress, USACE Generals, US and Washington Department of Fish and Wildlife, NOAA Fisheries (NMFS), Washington DOT, County Commissioners, Weyerhaeuser, and local landowners, among others.

Work involved managing a multi-disciplinary team involving original design, value engineering, environmental compliance (NEPA), specification writing, plus construction oversight of the weir-and-baffle system feature and large woody debris “islands” within the sediment plain and braided river flow path.

These features were designed to build up sediment deposition high in the Mt. St. Helens sediment plain in the North Fork Toutle River Valley to help alleviate downstream flooding along communities of the Cowlitz and Columbia River systems.



  • Public involvement:  Town Hall Meetings, Press, Congressional visitation
  • Original Design and Innovative, Unique Construction
  • In-Water Work, within Government work period guidelines
  • Various natural and man-made features
  • Upstream and downstream fish passage
  • Soil Exploration and Analysis
  • Construction Oversight
  • Air crane (helicopter) assisted construction during the follow-on contract
  • Remote video surveillance and analysis



Results of the project provided what the design intended during the first wet weather season, and the initial project gave way to a greater understanding of the surrounding geomorphology, construction methods, and ecosystem in the Toutle River Valley.  

The results continued to be studied today by Dr. Colin Thorne of the University of Nottingham to help realize the effects of the structure on the sediment plain and sediment retention across the valley.

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