Before revision: 500px|The lake retention time for a body of water with the volume 2000 m3 and the exit flow of 100 m3 per hour is 20 hours.
After revision: (70,000 cu ft)(3,500 cu ft)500px|The lake retention time for a body of water with the volume 2000 m3 and the exit flow of 100 m3 per hour is 20 hours.