Water storage lagoons are bodies of water used in order to store water for a variety of purposes. Storage lagoons are used to keep water needed for irrigation, livestock, and other industrial purposes. They can also be used to store wastewater that needs treatment before being returned to the environment. Or, a lagoon may be used as secondary containment when theres a chance of another lagoon or container overflowing.
A water storage lagoon differs from a pond in its utility. A pond may be serve purposes, but its primary goal is to simply be a pond. A lagoon is specifically built to use water for a particular purpose.