The Myakka sent about 3 feet of water into homes in a Sarasota County subdivision, which had privately maintained the levy.
More than 10 inches of rain have fallen since Wednesday in the region southeast of Tampa. Scattered sections of Manatee and Citrus counties reported up to 20 inches last week.
A jammed flood gate forced the temporary evacuation of hundreds of people who live downstream from Lake Manatee as the swollen reservoir threatened to burst its banks following torrential rain.
The malfunctioning flood gate, one of three on the reservoir's dam, prevented authorities from releasing enough water from the 2,400-acre lake to keep up with water flowing into the reservoir.
Officials urged the evacuation of 600 homes along the Manatee River on Sunday morning. Crews pried open the gate by Sunday afternoon, and the lake began to drain normally, Manatee County spokesman Jay Moyles said. Evacuees were given permission to return to their homes Sunday evening.
It rained again in the area Monday, with the heaviest showers south of Lake Manatee.
"It looks like we're going to get a break," said Eric Oglesby, hydrologist at the National Weather Service in Ruskin. "We should have a couple days of fairly dry weather."
Some rural roads near the lake were still under water Monday, but only in uninhabited areas, said Larry Leinhauser, director of Manatee County Emergency Operations.