Engineers on Monday ruled out a feared second breach in a Florida wastewater reservoir that risks flooding nearby communities with millions of gallons of contaminated water.

The state Department of Environmental Protection (DEP) said experts were "on-site today evaluating conditions and determined the site was safe to continue work."

Emergency workers, assisted by the Florida National Guard, have been pumping about 33 million gallons daily out of the wastewater reservoir, which has sprung a growing leak in its plastic lining.

The water from the Piney Point site is being discharged into Tampa Bay.

More than 300 homes near the abandoned phosphate mine and fertilizer-production facility were put under mandatory evacuation orders at the weekend, and Governor Ron DeSantis declared a state of emergency to free up funds to tackle the crisis.

Some prisoners from a county penitentiary have been bussed to an undisclosed location, while others were moved to higher floors in the building.

The contaminated water was being pumped out to avoid what authorities warned could be a "catastrophic" flood.

The governor said the wastewater has higher phosphorous and nitrogen levels.

Marine algae thrive on such elements, and environmental groups fear the release of millions of gallons of nutrient-rich water into the ocean could trigger a deadly "red tide," or algal bloom, that can suffocate fish and other aquatic life and deter tourist activity.

Florida Republican Congressman Vern Buchanan said the situation was "very concerning" and called for the Environmental Protection Agency to step in.

A collapse of the reservoir also risked sending water into nearby stacks of phosphogypsum, a leftover from fertilizer production.

Phosphogypsum is considered radioactive as it contains isotopes such as radon, as well as toxic heavy metals like arsenic, lead and mercury.

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