Officials instead chose to open all six floodgates at 0400 UTC on December 12 , which released about 1.6 million gallons ( 6.1 million liters ) of water into the river every second . Officials instead opted to open all six floodgates at 0400 UTC on December 12 , which released about 1.6 million gallons ( 6.1 million liters ) of water into the river every second .