Earlier this month, the National Transportation Safety Board released a marine accident brief on the 2013 grounding and sinking of the towboat Stephen L. Colby

The towboat struck hard bottom in the Upper Mississippi River (UMR) and partially sank off the right descending riverbank in LeClaire, Iowa, on Nov. 25, 2013, at 15:55 central standard time. Six of the nine crewmembers on board made it to the riverbank on their own. The nearby towing vessel Aaron F. Barrett recovered the remaining three crewmembers from the partially sunken vessel. No one was injured. The Coast Guard estimated the 2,096 bbls. of petroleum products were recovered from the vessel and river.

The area of the UMR where the Stephen L. Colby grounded is known to require particular caution during periods of low water because the bottom is hard rock with a stepped or shelf formation. On Nov. 16, 2013, the port captain for Marquette Transportation, owner of the towboat, sent an e-mail reminder to all company vessel operators to use caution while transiting two specific areas of the waterway: the area just below Lock & Dam 14 and the vicinity of UMR mile 497, just upstream of the accident site. The mate stated that he was not aware of this e-mail but he knew those areas of the UMR presented special risks. The accident caused about $3.9 million in damage.

The National Transportation Safety Board determined that the probable cause of the grounding and sinking of the Stephen L. Colby was the failure of the master and mate to ensure sufficient underkeel clearance for the intended transit through the accident area.