Public Notices

Draft SEIS: Mount St. Helens Long-Term Sediment Management Plan

Published Aug. 20, 2014

Public Notice


Mount St. Helens Long Term Sediment Management Plan

Cowlitz County, Washington


                                                                                                       Issue Date: August 15, 2014                                           Expiration Date: Sept 29, 2014




The U.S. Army Corps of Engineers, Portland District (Corps) is seeking public comment on the Mount St. Helens Sediment Management Plan Supplemental Environmental Impact Statement.  The Corps is evaluating several alternatives in the draft SEIS, outlining strategies to manage flood risk to established levels for the cities of Castle Rock, Lexington, Kelso and Longview, Washington through the year 2035.   The draft SEIS is available on the Corps webpage at:


The public comment period begins Aug. 22, 2014 and continues for 45 calendar days. Comments must be received via email, or via traditional mail, must be postmarked by Oct. 6, 2014.


The original Mount St. Helens Sediment Management plan, authorized in 1985, included construction of a sediment retention structure, levee improvements and dredging.  In addition, the original plan indicated that additional sediment management actions would be needed sometime after year 2000 and acknowledged other actions besides dredging might be more appropriate in the future. Current efforts focus on identifying remaining actions needed to complete the original MSH project and the associated impacts. 


Current data indicates additional sediment management actions are needed to prevent increased flood risks associated with sediment deposition in the lower 20 miles of the Cowlitz River.  Recent assessments show that unless further actions are implemented, sediment buildup in the lower Cowlitz River will continue and increase the flood risk for more than 50,000 people, their homes and businesses.  Flood risk levels for the communities of Lexington, Kelso, Castle Rock and Longview would continue to deteriorate as the river channel fills with sediment.  Without sediment management actions, the floodwaters could eventually overtop the levees and significantly impact the communities. 


Three alternatives were identified that would address the flood risks associated with sediment build up in the lower Cowlitz River through 2035.  They are:


1.       Cowlitz River dredging only

2.      SRS spillway and embankment raise

3.      A phased construction plan consisting of:

a.       SRS spillway crest raises

b.      Grade-building structures

c.       As needed dredging


Environmental impacts for the three alternatives have been evaluated and are reported in the draft SEIS.  The SEIS was prepared by the Portland District.  Formal consultation with the U.S. Fish and Wildlife Service (USFWS) and the National Marine Fisheries Administration (NMFS) is also being conducted for the preferred plan. 


The Corps has selected the phased construction alternative as its preferred alternative.  Based on research and analysis, the Corps determined that this alternative provides specific actions and necessary flexibility to manage the flood risk to cities near the Cowlitz River. For more information about the preferred alternative and all other alternatives, please see the draft SEIS document on the Corps’ website.


Public Comment: The public comment period is intended to provide those interested in or affected by this action, an opportunity to make their concerns known. Specifically, the Corps is seeking input that can inform our decision or analysis. After receiving public comments, the Corps will be addressing substantive comments and incorporating them into a final SEIS which will be made available to the public.  


Public Meetings: The Corps will be hosting two open house public meetings in September, in Toutle and Longview, Washington.


Public Meetings:

September 10, 2014, 5 p.m. to 7:30 p.m.

Cowlitz County Expo Center, 1900 7th Ave, Longview, WA 98632


September 17, 2014, 5 p.m. to 7:30 p.m.

Toutle High School multipurpose room, 5050 Spirit Lake Hwy, Toutle, WA 98645


Comment Timeframe: Comments on the draft SEIS will be accepted for 45 days from publication of the Notice of Availability in the Federal Register by the U.S. Environmental Protection Agency. The public comment period begins on August 22, 2014 and continues until Oct. 6, 2014. Comments must be received via email, or traditional mail must be postmarked by Oct. 6, 2014.

How to Comment: In your comments, please refer to the above public notice number (CENWP-PM-E-14-10), title and date. Written comments may be sent electronically to or by traditional mail to:

                                  Tim Kuhn

                                               U.S. Army Corps of Engineer District, Portland

                                               Attn:  CENWP-PM-F/Mount St. Helens draft SEIS

                                               P.O. Box 2946

                                               Portland, OR  97208-2946