Advanced maintenance dredging at the confluence of the lower Columbia and Cowlitz rivers to reduce risk to users by providing reliable passage of commercial and recreational traffic can proceed following a finding of no significant impact to the environment.
The U.S. Army Corps of Engineers, Portland District (USACE) developed an environmental analysis in accordance with the National Environmental Policy Act of 1969, as amended. The Final Environmental Assessment (EA) dated 21 October 2022, for Lower Columbia River Navigation Channel Advance Maintenance Dredging at Cowlitz River addresses the project purpose to facilitate navigation by removing shoals that restrict the movement of vessels. The project is located near river mile 68 in Cowlitz County, Washington. USACE currently conducts advance maintenance dredging in this location as part of the Lower Columbia River Federal Navigation Channel (LCR FNC) maintenance.
The proposed action, which is the preferred alternative, includes advance maintenance dredging to establish a sediment trap at the mouth of the Cowlitz River. USACE also considered the no action alternative. Under the no action alternative, USACE would not perform advance maintenance dredging of the Cowlitz River sediment trap. Instead, USACE would continue to maintain the navigation channel by dredging the sediment after it migrates from the Cowlitz River into the Columbia River and forms a shoal in the LCR FNC. The No Action Alternative would result in reactive dredging of the LCR FNC frequently throughout the year when shoaling develops. The limited dredge equipment available would not be able to quickly respond to address shoaling elsewhere in the 100-mile-long LCR FNC which could reduce channel reliability for users and result in shipping restrictions.
USACE prepared a Finding of No Significant Impacts (FONSI) under the authorities as outlined below. Congress authorized USACE to construct and improve federal navigation projects over time. Generally, Congress authorizes federal navigation channels by specific dimensions (depth and width). Congress has specifically authorized construction of, and improvement to, the LCR FNC by the Rivers and Harbors Acts (RHA) of 1878, 1892, 1902, 1912, 1930, and 1962, and most recently the Water Resources Development Act (WRDA) of 1999 and Consolidated Appropriations Act of 2004. Implicit in Congressional authorization to construct is a USACE non-discretionary duty to continue operating and maintaining project features. Congress also provides USACE with annual appropriations for LCR FNC operation and maintenance activities.
In carrying out LCR FNC maintenance dredging and placement activities to meet authorized dimensions, USACE complies with Sections 102 and 103 of the MPRSA of 1972, Sections 401 and 404 of the CWA of 1977, and regulations at 33 Code of Federal Regulations (CFR) parts 335 through 338 (“Operation and Maintenance of Army Corps of Engineers Civil Works Projects Involving Discharge of Dredged or Fill Material into Waters of the U.S. or Ocean Waters” and affiliated procedures, etc.). The Corps has determined that the Final EA, incorporated herein by reference, has appropriately assessed and disclosed the environmental impacts of the reasonable alternatives considered in the EA including the Proposed Action.
The draft EA was made available for a 15-day public review period, from September 30 through October 14, 2022. USACE requested comments from federal and state agencies, as well as interested parties including interest groups and tribes. Comments were received from the Environmental Protection Agency (EPA), US Fish and Wildlife Service, and Oregon State Marine Board. As a result of state and agency review, the final EA was revised to incorporate the relevant recommendations.