When we say environment for reservoirs what do we mean?

A reservoir (/ˈrɛzərvwɑːr/; from French réservoir [ʁezɛʁvwaʁ]; lit. 'storehouse') is, most commonly, an enlarged natural or artificial lake, pond, or impoundment created using a dam or lock to store water. ... Defined as a storage space for fluids, reservoirs may hold water or gasses, including hydrocarbons.A single-purpose reservoir is designed to fulfill only one function, such as irrigation, power generation, navigation, flood control, water supply, recreation, or low-flow regulation. The trend has been toward construction of multiple-purpose reservoirs designed to serve at least two principal functions.

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