This environmental impact statement addresses the construction and subsequent operation of a new navigation lock at Bonneville Dam on the Oregon shore, south of the existing lock and powerhouse. The new lock would match the dimensions of the seven other locks on the Columbia-Snake River navigation system. Relocations required by the action would involve one building at the Corps of Engineers Hydraulic Lab and approximately one-quarter mile of the Union Pacific Railroad main line and siding. Lock construction would require the excavation of about 3.7 million cubic yards of earth and rock which would be placed on the low, downstream islands of Ives and Pierce. This action would eliminate existing vegetation and wildlife on these islands, and would raise large portions of the islands above the 10-year flood plain. Fish passage will not be significantly affected. Non-structural alternatives considered include: no action; modification of powerhouse operation to improve lock approach; and imposition of a congestion fee. Structural alternatives considered include: various alignments and dimensions for a new lock; rebuilding the existing lock; possible disposal sites for excavated materials; and delaying construction of a new lock by imposition of a congestion fee. Keywords: Locks(waterways); Excavation; Disposal; Waterway transportation; Inland waterways.