The low-water dam mentioned is just upstream of the Tulsa Wave site. Apparently this is the boat he was using.

Condolences to the family, and props to the Tulsa Fire Dept. Sounds like they got there quick and did their thing well.
FYI - river was running about 45,000 cfs at the time of the accident.
FYI2 - part of the river development project planned here is to rework this dam to remove the drowning machine effect and create whitewater features below the dam.