Although hydroelectricity is the least expensive energy source used to generate electricity most utility companies in The United States do not use this form of energy because?

Although hydroelectricity is the least expensive energy source to generate electricity but still it is not used by most of the companies as it changes the normal flow of water, affects aquatic organisms, hamper fish habitats etc.

Explanation:

As hydroelectricity is fully depend upon water flow so it may create several consequences like drought, or another natural calamity may affect potentially. This may also affect the aquatic organisms that are fully depend on aquatic body.

Moreover, there are limited reservoirs for hydroelectric power plant. Only few are functional.