(a) The draw of the Burlington Northern Grassy Point railroad Bridge, mile 5.44, shall open on signal except that, from December 15 through March 15 the draw shall open if at least 12-hour notice is given.

(b) The draw of the Canadian National Combined Railroad and Highway Bridge, mile 13.91, need not be opened for the passage of vessels. The owner shall return the draw to operable condition within a reasonable time when notified by the District Commander to do so.