Oregon Revised Statutes Shipping and Navigation § 783.590

Any person or corporation operating any steamboat or other watercraft upon the Willamette River above the City of Portland, shall so construct the smokestacks upon such steamboat or other watercraft with hinges so arranged that the smokestacks thereon can be lowered to a level with the pilot house upon such steamboat or other watercraft when necessary to pass under any bridge at any time constructed across the Willamette River.