The following is a marine accident brief from the National Transportation Safety Board (NTSB):
(WASHINGTON) — About 1200 local time on May 23, 2019, two loaded barges, MTC 7256 and LTD 11140, struck the Webbers Falls Dam. The barges had broken away the previous day from a fleeting area on the Grand River in Muskogee, Okla., during historic floodwaters and high river current. The two barges were total constructive losses. No pollution was reported. Total damages exceeded $4.7 million, including the amount spent to remove the barges and repair the dam ($3,956,249).
Probable cause
The National Transportation Safety Board determines that the probable cause of the barge breakaway and contact with the Webbers Falls Dam was the force of the river current acting on the moored vessels at the Grand River fleeting area, which exceeded the capacity of the mooring wires, due to the extreme rise and flow of water in the Grand River as the Fort Gibson Dam released major amounts of water in a short period of time.
Analysis excerpt
When the vessels broke free, the pilot and captain of the towing vessel Dennis Collins observed the upriver wire holding LTD 11140 parting first and the other wires parting seconds later. After the accident, investigators found parted cables attached to the mooring anchors. It is likely that the strain was not distributed evenly between the three wires, resulting in one line taking a large portion, or all the load, if the others had become slack. Once one line failed, the strain would be placed on the next line with the least amount of slack, which would also fail, until the breakaway occurred.
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