45 Years Later, the Engineers Who Faced the Volcano Remember

This story appears in America’s Engineers: The People, Programs, and Projects of the U.S. Army Corps of Engineers (2025-2026 Edition)

When a volcano erupts hurling millions of cubic yards of sediment onto the surrounding area and into local rivers, how does a community deal with it, and where does all that sediment go?

On May 18, 1980, 52 miles northeast of Portland, Mt. St. Helens spewed forth ash, lava, and earth. Following several earthquakes, a bulge that had formed weeks prior, collapsed and the magma in the mountain began to flow, flattening everything that it came in contact with.

The collapse triggered the largest known debris avalanche in recorded history. Mudflows, known as lahars, were a result of mud, debris, snow and ice and careened down the mountain. These lahars decimated bridges and lumber camps along the Cowlitz and Toutle Rivers.

This catastrophic event changed the landscape of the Pacific Northwest permanently. What once was a forested valley through which the Toutle River flowed, became a desolate moonscape. Today, forty-five years after the fact, trees, aquatic plants, and various forms of wildlife have returned to the area.

Amid the widespread ecological and commercial damage, proximity and speed were on the side of the U.S. Army Corps of Engineers, Portland District. The district responded, serving as one of the first federal agencies responding to the crisis onsite. Existing federal legislation provided for the Corps of Engineers to, “immediately react to emergency requirements and to initiate actions especially related to protecting lives and property,” said Terry Connell, the former Portland District Commander at the time of the event.

A Threat of Flooding

Over 200 million cubic yards — enough to fill the Moda Center five and a half times — sediment choked the Cowlitz and Toutle Rivers, and waters threatened to overflow their banks. Engineers quickly identified that an overflow of the Cowlitz would be life threatening to the downstream population of places such as Kelso and Castle Rock.

The water levels of Spirit Lake began to rise as sediment and debris clogged the natural flow, leading to a rise in water levels, creating a potential flood threat, a threat that would add to the chaos in the aftermath of the eruption. The lake was poised for disaster if water, or more debris, came into the lake, or if the debris of this newly created dam shifted, water would overwhelm the already stressed river system. Along the Cowlitz River, USACE raised levees to contain the water and prevent any debris and sediment from spilling into the surrounding areas.

“We needed to take control of the situation before things got out of hand,” Connell explained.

Restoring Navigation

With the flood risk contained, the attention of USACE switched to restoring navigability of the waterways. Debris from the avalanche gridlocked the rivers, a vital source of transportation of goods and industry in the area and prevented any movement. To continue to support their efforts, USACE utilized four hopper dredges to help widen the channels and clear the waterways, three belonging to USACE and one belonging to the Port of Portland.

Within three weeks, narrow and confined travel was restored to the rivers. Within 90 days, the channel was restored at the authorized depth. Over the span of two to three months, USACE continued to increase the size of the width with supervision of the Coast Guard; a timeline that far exceeded the expectations of the agencies involved.

“The local population wanted to see results in real time, and we delivered,” said Connell.

Looking Back, 45 Years Later

Following the 45th anniversary of the eruption, a group of personnel who had been with USACE at the time of the eruption and those who helped facilitate USACE efforts years later, gathered at the Mt. St. Helens Visitor Center. The exchange of stories, smiles, and the sounds of these men and their families were almost palpable. After pleasantries were exchanged, introductions made, and a tentative convoy formation was laid out, they then traveled to the Sediment Retention Structure (SRS) to reminisce and to see what things are like now.

For Rick Goodell, returning to the Sediment Retention System was like an alumnus visiting his alma mater. Goodell was a Deputy Commander serving as the Contracting Officer, which then oversaw all contracts for the Portland District, at the time that the SRS was installed. The eruption had happened several years before, once the immediate issues were addressed, it was time to focus on what would happen to the millions of cubic yards of sediment that were still in the river system.

The solution was the SRS—an embankment, outlet works, and a spillway—that slowed the flow of water to allow debris to settle rather than be carried downstream. Stopping the sediment further up the river was much more cost effective as it prevented further problems, and it meant the costs would be much less for dredging.

Since 1986, when he was the deputy commander, Goodell has seen USACE use the lessons it learned during the eruption and subsequent restoration, to manage other emergency situations such as the flood of 1996.

“Portland District really comes together when there is an emergency, whether it is Mt. St. Helens or the flood of 96,” said Goodell.

This story appears in America’s Engineers: The People, Programs, and Projects of the U.S. Army Corps of Engineers (2025-2026 Edition)

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