TAMPA, Florida — Hurricane Frances carved a huge gap in the wall of a fertilizer company reservoir, spilling 41 million gallons of acidic waste that posed a threat to aquatic life in a bay near Tampa.

It could be days or weeks before a solid assessment of the environmental effect is available, said Rick Garrity, director of Hillsborough County's Environmental Protection Commission.

"If we find significant impact, we'll keep following up," Garrity said.

The breach in a berm surrounding the reservoir happened during the storm Sunday, starting as a 6-foot-wide gap created by storm-driven waves in the reservoir, then growing quickly to 30 feet across and finally to 50 feet, said officials of Cargill Crop Nutrition, a unit of Cargill Inc.

An overflow ditch couldn't handle the spill, and for a while the company ran out of a caustic solution used to buffer acid in the escaping wastewater. Then the storm prevented crews from beginning repairs.

It wasn't until midday Monday that the company announced that the wastewater had stopped flowing into a creek that feeds Hillsborough Bay, on the northeast side of Tampa Bay.

"It's a serious spill," company Vice President Gray Gordon said. "We're very upset about this, very concerned."

The spill threatens fish and other wildlife, not people, pets, or livestock, officials said.

The wastewater from phosphate production is high in nitrogen and phosphorus, which promote the growth of algae that can reduce the amount of oxygen in the water.

Garrity said his agency and the state Department of Environmental Protection had warned Cargill about the levels of wastewater being stored on the property.

There could be fines, and regulators also could make the company pay for environmental damage and change its water retention design, Gordon said.