Public Notices

Final Supplemental Enviromental Impact Statement

Published Aug. 8, 2018


Cowlitz County, Washington     

 Issue Date: August 9, 2018
   Closing Date: September 10, 2018

The U.S. Army Corps of Engineers (USACE), Portland District, is providing for public review, the Final Supplemental Environmental Impact Statement (FSEIS) for the Mount St. Helens Long-Term Sediment Management Plan. USACE is the lead agency for the FSEIS under the National Environmental Policy Act of 1969 (NEPA), 42 U.S.C. §§ 4321–4347. 

A Draft SEIS (DSEIS) was issued in October 2014. Following the completion of the public comment period for the DSEIS, USACE engaged in consultation with the National Marine Fisheries Service (NMFS) as required by the Endangered Species Act (ESA). This consultation resulted in the need to develop alternatives to ensure the sediment management plan would not jeopardize listed species or adversely modify or destroy the species’ critical habitat. USACE provided a second public comment period on a revised DSEIS to give the public an opportunity to comment on revisions to the DSEIS, including fish conservation measures.  In September 2017, USACE published for public comment the revised DSEIS to give the public and interested stakeholders an opportunity to comment on changes to the SEIS and on the fish conservation measures. The public comment period was from September 15, 2017 to November 6, 2017.

Proposed Action: In 1984, USACE issued an EIS which evaluated alternatives in managing sediment flowing downstream from the debris avalanche to avoid flooding in the Cowlitz River and disruption of navigation on the Columbia River caused by sediment buildup. The 1985 Mount St. Helens Sediment Management Decision Document included construction of a sediment retention structure (SRS), levee improvements and dredging. The 1985 Decision Document recognized the likely need for a future re-evaluation of the long-term sediment management measures based on changes in future conditions. The SRS was completed in 1989. Since the SRS began operating as a run-of-the-river structure in 1998, increased sediment from the North Fork Toutle River basin is being transported downstream and accumulating in the lower Cowlitz River.  USACE has conducted a limited re-evaluation of sediment management in the North Fork Toutle River and is proposing to implement updated sediment management measures to manage flood risk to established levels for the Washington cities of Castle Rock, Lexington, Kelso, and Longview through the year 2035. In addition to a No Action alternative, three sediment management alternatives were identified and evaluated that would address the flood risks associated with sediment build up through 2035. They are:
• Cowlitz River dredging only
• SRS spillway and embankment raise
• A phased construction plan (preferred alternative) consisting of:
o SRS spillway crest raises
o Grade-building structures
o Dredging, as needed

The FSEIS also includes an evaluation of the fish conservation measures that were developed to ensure the proposed sediment management plan will not jeopardize the continued existence of any endangered or threatened species or adversely modify or destroy the species’ designated critical habitat. Fish conservation measures evaluated include:
• Replace the fish collection facility on the North Fork Toutle River operated and maintained by the Washington Department of Fish Wildlife (WDFW) and establish a fish release site on Deer Creek
• Modify the fish collection facility on the North Fork Toutle River and establish a fish release site on Deer Creek

Environmental impacts of the no action, sediment management alternatives and fish conservation measures are evaluated in the FSEIS.

The FSEIS includes information on the discharge of dredged or fill material that may occur during construction of the preferred alternative, as well as information on waters of the United States present within the project area and the impacts on those waters under Section 404 of the Clean Water Act (CWA). If dredging is necessary in the lower Cowlitz River, it would include dredging, dredged material placement and storage, and monitoring.  Mechanisms for potential effects include the movement of sediment from the river channel, up through the water column, and onto upland storage stockpile locations.  Dredging activities would be conducted by two to three hydraulic dredges operating at various reaches of the lower Cowlitz River. Dredging would occur during the in water work window, as determined in coordination with WDFW.  Prior to dredge material placement, a field wetland determination would be conducted to confirm the absence or presence and acreage of wetlands.  A sample of past dredged material placement sites, that could potentially serve as future placement sites, were surveyed in 2013 for wetland and habitat conditions.  Of nine sites surveyed, only one site had wetlands.  Discharge of dredged or fill material will be evaluated using the guidelines under Section 404(b)(1) of the CWA. A Section 404(b)(1) analysis is found in Appendix G of the FSEIS.

Endangered Species:  USACE has completed formal consultation with the National Marine Fisheries Service (NMFS) as required by Section 7 of the ESA. NMFS issued a Biological Opinion (BiOp) in August 2017. The BiOp concluded that the preferred alternative was likely to jeopardize the continued existence of threatened Lower Columbia River (LCR) coho salmon and LCR steelhead and likely to result in the adverse modification of both species’ designated critical habitat.  The BiOp includes a Reasonable and Prudent Alternative (RPA) to ensure the preferred phased construction alternative does not jeopardize the continued existence of any endangered species or threatened species or result in the destruction or adverse modification of designated critical habitat.

After USACE received the NMFS BiOp and assessed potential effects of the RPA fish conservation measures, the informal consultation with U.S. Fish and Wildlife Service (USFWS) resumed in October 2017 and was completed on January 17, 2018. USFWS concurred with USACE that the effects of the preferred fish conservation measure would be not likely to adversely affect (NLAA) on bull trout.  USACE and USFWS agreed upon conservation measures that would be implemented for placement of dredged material, with the inclusion of these conservation measures, USFWS concurred with USACE’s NLAA determination for streaked horned lark and Nelson’s checkermallow.

Historic Properties/Cultural Resources: Section 106 of the National Historic Preservation Act of 1966, as amended (54 USC 306108), requires Federal agencies to consult with the appropriate State to take into account the effects of actions they undertake on historic properties listed in or eligible for listing in the National Register of Historic Places.  Due to the phased approach of this alternative, USACE, in consultation with State of Washington, Department of Archaeology and Historic Preservation, the Cowlitz Indian Tribe and other interested parties, is developing a programmatic agreement that will lay out a mutually agreed upon approach to the management of those NRHP-eligible resources potentially adversely effected by this action, continued consultation, and mitigation. The USACE will need to determine eligibility for each of the five resources that will be adversely affected within the sediment plain due to the SRS spillway crest raise. The SRS, a National Register eligible historic property, will not be adversely affected as the structure was designed to be raised as needed.

Public Review: The public review period is intended to provide those interested in or affected by this action an opportunity to review the FSEIS. Upon completion of the public review period, USACE will consider any comments submitted in the preparation of the record of decision (ROD). The ROD will document the USACE’s decision.

An electronic copy of the FSEIS is available for download at:

Additional information may be found at the project’s webpage:

All comments received will become part of the administrative record and are subject to public release under the Freedom of Information Act, including any personally identifiable information such as name, phone numbers and addresses.

The FSEIS will be available for public review for 30 days after publication of the notice of availability in the Federal Register by the U.S. Environmental Protection Agency.  Comments must be emailed or postmarked by September 10, 2018. 

Written comments may be sent via email to or by traditional mail to:

U.S. Army Corps of Engineers, CENWP-PM
ATTN: Mike Turaski
P.O. Box 2946
Portland, OR 97208-2946