The Columbia River is of course migratory habitat for endangered species including Salmon and Steelhead, so construction of the IBR has to be sensitive to these issues.
Among the permitting agencies, the U.S. Army Corps of Engineers publishes as standard in-water work window of November to February. The IBR project however has argued that this would unjustifiably lengthen the number of years required for construction. A Biological Assessment published last year suggests the project would seasonably restrict some activities:
But the same document proposes no restrictions on other activities:
Of particular interest are vibratory hammers and oscillators. ODOT is currently using oscillators to drive pilings for the Abernethy Bridge on I-205 at Oregon City. Interestingly, the Army Corps only appears to be allowing use of oscillators on the Abernethy from July 1 to December 31.
Why are the fish in the Columbia deserving of less protection? Will the Army Corps issue IBR a permit for year-round use of oscillators and vibratory hammers?