Mint Springs Valley Park in Albemarle County is open following multiple tests showing normal water quality.
County government had announced a temporary closure to swimmers last week after finding a harmful algae bloom.
Chris Greene Lake Park and Walnut Creek Park were not affected.
Beginning June 1, all three county lakes will observe summer operating hours, open seven days a week from 10 a.m. to 6 p.m., through Aug. 9.
After Aug. 9, hours will transition back to weekends only at Chris Greene Lake until Labor Day, September 7.