Sediment Management Plan for Mount St. Helens Up for Comment

The U.S. Army Corps of Engineers is seeking public comments on proposed updates to its decades-old long-term sediment management plan for Mount St. Helens.

In an updated draft of the supplemental environmental impact statement for its plan, the Corps proposes the phased construction of two incremental spillway crest raises at the sediment retention structure on the North Fork Toutle River, followed by the construction of grade-building structures on the sediment plain upstream from the main structure.

Dredging of the lower Cowlitz River would also be performed as needed, USACE said.

The Corps has been fighting sediment erosion at Mount St. Helens since the volcano’s 1980 eruption triggered a debris avalanche, which deposited more than three billion cubic yards of sediment into the Toutle River basin.

Recognizing that erosion from the debris avalanche would result in elevated sediment loads for several decades, the Corps completed a long-term management plan.

The public comment period is intended to provide those interested in the proposed actions an opportunity to make their concerns or comments known.

Upon completion of the public comment period, the Corps will consider all comments submitted on both the original and this updated draft of the supplemental environmental impact statement before issuing the final document.

The final document will include responses to comments received on both the original and this revised draft.

The Corps will consider all comments received or postmarked by November 6.