What is Reservoir Turnover?

A turnover is when water basically flips in a body of water. Turnovers in reservoirs are from temperature stratifications and can cause taste and odor issues with the water. A turnover can be caused by high temperatures during the day and low temps at night, such as what southwest Colorado experienced in August at both the Vallecito and Town of Bayfield reservoirs. They also can take place later in the fall or early in the spring when air temperatures match the water temperature. When the surface temperature of the water cools below 50 degrees, the water on the top grows heavier, so it goes down to the bottom of the reservoir, and the water on the bottom rises to the top.