CENWP-PM-E-24
Issue Date: July 31, 2025
Expiration Date: August 15, 2025
15 Day Notice
Interested parties are hereby notified that the U.S. Army Corps of Engineers, Portland District (USACE) is providing public notification of a proposed discharge of dredged material as required by the provisions of section 401 and 404 of the Clean Water Act (CWA) via the Bonneville Dam Nav Lock 1 Maintenance Dredging and Placement, CWA Section 404(b)(1) Evaluation. The Preferred Alternative is a temporary project that would address the need for the replacement of steel stoplogs with new precast, pre-stressed concrete stoplogs to meet current USACE guidance, at Bonneville Dam in the Columbia River.
Replacement of the stoplogs requires approximately 2500 cubic yards of sediment buildup in the NL1 stoplogs slot/upstream concrete apron be removed via dredging and subsequent in-water placement of the removed sediment downstream (Columbia River Mile 141). The attached CWA 404(b)(1) evaluation describes any unavoidable impacts to non-wetland waters of the U.S. that would occur as a result of proposed actions related to Bonneville Dam Nav Lock 1 (NL1) Maintenance Dredging and In Water Sediment Placement and demonstrates USACE’s compliance with the 404(b)(1) Guidelines in the National Environmental Policy Act (NEPA) document prepared for the action.
USACE is evaluating the project via the Categorical Exclusion/Record of Environmental Consideration process as described by USACE’s regulations for implementing NEPA, 33 CFR §230.9, (b) Activities at completed Corps projects which carry out the authorized project purposes. This determination is based upon the authorized primary purposes for the Bonneville Lock and Dam being navigation and power generation, and maintenance dredging of NL1 (in order to perform required upkeep to ensure safety and full operability of the structure) is supportive of the authorized primary purposes as described in the 2020 Columbia River System (CRS) Operations Environmental Impact Statement (project system or non-routine maintenance) prepared in response to the need to review and update overall operations, maintenance, and configuration of the 14 CRS multiple purpose dams and related facilities. The proposed action is in accordance with the Categorical Exclusion 33 CFR §230.9(b) because it is necessary to carry out the authorized project purposes as a routine operation and/or maintenance activity.
The replacement of the NL1 steel stoplogs with new precast, pre-stressed concrete stoplogs would allow USACE to subsequently accomplish: lock dewatering, inspections, and deferred maintenance on the original Bonneville Dam Navigation Lock.
Important objectives of the project include:
- Dredging approximately 2500 cubic yards of sediment buildup in the NL1 upstream stoplog slot.
- In-water placement of the dredged sediment at Columbia River Mile 141.
- Installation of the new precast, pre-stressed concrete stoplogs at the NL1 upstream stoplog slot.
- Note: The Proposed Action covers the dredging and NL1 new stoplogs placement, any subsequent O&M inspections or NL repairs shall be addressed as required via future environmental analyses.
Agency Coordination:
USACE coordinated the proposed project through the Columbia River Fish Passage Operations & Maintenance (FPOM) coordination team, an intra-agency group that includes representatives from the: USACE, NOAA Fisheries, US Fish and Wildlife (USFWS), Bonneville Power Administration (BPA), state fish agencies (OR), tribes, and other interested parties. The Project was first coordinated and received concurrence from the FPOM group 31 May 2023. The project was paused and later revisited this year where it will again go to FPOM in July 2025.
Assessment of the Need for an Environmental Impact Statement:
The proposed action is categorically excluded from NEPA per 33 CFR §230.9(b). Based upon the review of the action, the action complies with all applicable federal cultural and environmental laws, regulations, and executive orders. No extraordinary circumstances have been identified and no further NEPA analysis is required.
Cultural Resources Consideration and Tribal Consultation:
Nation-to-Nation consultation was conducted with the following Federally recognized Tribe(s): Nez Perce Tribe, the Confederated Tribes and Bands of the Yakama Nation, the Confederated Tribes of the Warm Springs Reservation of Oregon, and the Confederated Tribes of the Umatilla Indian Reservation.
Water Quality Certifications:
The Preferred Alternative would involve activities resulting in the discharge of dredged material subject to Section 401 and 404 of the Clean Water Act. Section 404(b)(1) evaluation and Section 401 water quality certification is required. Section 401 water quality certification was submitted to WA Dept of Ecology on 26 Oct 2023, with technical updates provided 30 Nov 2023. Certification was granted on 6 June 2024. All work will be conducted during the established in-water work windows and any anticipated related dredging and discharge to be conducted by others shall be deconflicted (for water quality and aquatic species protection) by USACE Dredging and Waterways Maintenance office. Section 404(b)(1) evaluation was prepared and made available via the subject public notice in July 2025
Endangered Species Act Consultations:
Impacts of System/Unscheduled maintenance activities such as the NL1 upstream stoplog slots dredging have been considered in the 2020 Columbia River Power System Operations Biological Opinion. (CRSO, BiOp No. WCRO 2020-00113 and US Fish and Wildlife Service (USFWS) BiOp No. 01EWFW00-2017-F-1650). The BiOp states that "Unscheduled maintenance can occur any time there is a problem or unforeseen maintenance issue or emergency that requires a project feature, such as a generator unit, to be taken offline in order to resolve." and “These events are communicated through the appropriate teams under the Regional Forum, such as the FPOM coordination team and TMT, to minimize negative effects on fish.” All work will be conducted during the established in-water work window, and after the project has been coordinated with FPOM (BON NL1 FPOM coordinations completed 9 Nov 2023, pending 2025 FPOM date(s)). Therefore, a separate Section 7 Consultation is not required for this project.
Additional Information and Comments: Questions or comments regarding the draft document should be directed to Mrs. Jess Hamilton, (541) 506-8317, jessica.t.hamilton@usace.army.mil at the address below. Mailed comments must be postmarked by the above closing date and sent to:
District Engineer
U.S. Army Corps of Engineer District, Portland
Attn: CENWP-PM-E/Jess Hamilton
P.O. Box 2946, Portland, Oregon 97208-2946
In your response, please refer to the above public notice title, and date. A “no comment” response will be assumed if no response is received prior to or postmarked by the above expiration date.
Figure 1: Overview map of Bonneville Lock and Dam Project.
Figure 2: Image overview of the Bonneville Navigation Lock work area and project buildings.