Manatee County Director of Public Safety Jacob Sauer said crews worked overnight on Friday in an attempt to fix the leak, but were unsuccessful.
He said a portion of the containment wall at the leak site had shifted laterally, and on-site engineers deemed the situation to be worsening. All command staff and residents were told to evacuate.
Acting Manatee County Administrator Scott Hopes told a press conference there were concerns the water could flood the area.
He said: “The risk that we’re dealing with right now is an uncontrolled release.
“There’s a very thick liner — think of it as a soft swimming pool. [The engineers] rightly identified that that leak was in the base of the southeast corner of that pool, so now what you see is, you see that opening.
“If that liner continues to unzip — because it’s probably at a seam — when that opens up, you will see the crevice where the breach has occurred continue to unzip and break that rock away.”