The Tulsa District of the U.S. Army Corps of Engineers reports that there was minimal structural damage to Webbers Falls Lock and Dam after two uncontrolled barges made contact at 11:58 am on May 23.
However, the Corps says the two barges, which capsized and are submerged below the water on the upstream side of the dam, are obstructing spillway gates 7, 9 and 10 from being able to fully close.
The barges made contact with the dam at the piers for gates 7/8/9 and 10. They quickly capsized, and the Corps says current water conditions make it unclear how much barge debris, if any, may have passed through the dam.
Webbers Falls Dam is on the Arkansas River south of Muskogee, Okla. The dam is a rolled earth material. The total crest length of the structures – including the spillway, powerhouse intake and navigation lock – is 4,370 feet. The spillway extends across the left half of the existing river channel. The spillway is a gated, concrete ogee weir with 12 50-by-41-foot tainter gates, separated by 11 10-foot intermediate piers.
The reservoir impounded by the dam has a surface area of 10.900 acres. The water is used to generate electricity from a 60-MW powerhouse containing three turbine-generator units, which began operating in 1970.
The area, along with upstream watersheds, has been experiencing excessive rainfall. Knowing the barges were loose and headed downstream, the Webbers Falls Lock and Dam staff ensured all tainter gates were fully elevated, to minimize damage in advance of the barge strike.
The flood of record occurred in May 1943 with an estimated peak discharge at the dam site of 720,000 cfs. As of 9 am on May 24, the dam was experiencing inflow of 484,088 cfs and releasing 456,700 cfs.
Immediately after the barges made contact, Tulsa District engineers were deployed to the structure. Initial observations were that the structural damage is minimal and there are no integrity issues that make the Corps concerned that the dam will not perform as designed. The Corps says it will continue to monitor and assess the dam as water conditions change.
The barges were carrying about 1,500 tons of phosphate-based, non-toxic fertilizer, and the Tulsa District Environmental Specialist is coordinating with the barge owner, U.S. Coast Guard and others on the spill response. Tulsa District Operations Division leaders are coordinating with the barge owner on the salvage operation to remove the debris.