water power

Short definition from Wiktionary

Noun

1. 1
   Mechanical or electrical energy derived from running or falling water; originally obtained from a waterwheel immersed in a stream; modern hydroelectric power is obtained from turbines fed from reservoirs.
2. 2
   A site capable of generating power or the right to use a site to generate power.
3. 3
   The capacity to shoot water, as from a fire hose or squirt gun