No towboat may tow any raft or boom of logs or piling that exceeds 1,500 feet in length from bow of towboat to stern of tow. No such tow may exceed 120 feet in width. When freshet stage of water in the Willamette River exceeds 10 feet, no tow may exceed 60 feet in width. The Harbor Master may allow larger tows than specified here if it is necessary and cannot be made smaller, but a patrol boat or some other craft must accompany the tow.