When entering / exiting my marina, I pass under a low clearance bridge (+/- 13'6'). While not a problem for me, some the larger boats have 6 - 12 inches of clearance based on pool level. Clearance varies if TVA is generating power, recent rain fall, etc. The clearance can RAPIDLY disappear with wake from even the smallest boats. This area is not marked as a no wake zone. Are there any CG regs which apply or is it simply safe and courteous boating? I have seen other boats blast under the bridge at WOT.