What does lake retention time refer to?

Lake retention time refers to the average time it takes for water to move through a lake. It is calculated by dividing the volume of the lake by the average outflow rate. The retention time of a lake is an important factor in determining its water quality, as it affects the amount of time pollutants have to break down or be removed.

Lakes with short retention times (less than a few weeks) are more susceptible to pollution, as pollutants do not have enough time to be broken down or removed. Lakes with long retention times (several years or more) are less susceptible to pollution, as pollutants have more time to be broken down or removed.

The retention time of a lake can vary significantly depending on the size of the lake, the amount of inflow and outflow, and the climate. Lakes in cold climates tend to have longer retention times than lakes in warm climates, as the cold water slows down the decomposition of pollutants.