a city dams a river and makes a lake that stores its freshwater supply. this an example of an artificial

This is an example of an artificial reservoir, which can also be used for hydroelectricity.

A freshwater lake that is formed by a city damming a river is an example of an artificial reservoir.

Explanation:

A reservoir can be classified into the category of natural reservoirs or artificial reservoirs depending on their formation. If the reservoir is formed due to the 'accumulation of water' in a naturally occurring depression, it is a natural reservoir. On the other hand, if the reservoir is formed by damming the natural course of water flowing through a river or a stream, it is called an artificial reservoir.