Since hydroelectric generators can be started or stopped almost instantly, hydropower is more
responsive than most other energy sources for meeting peak demands. Water can be stored
overnight in a reservoir until needed during the day, and then released through turbines to
generate power to help supply the peakload demand. This mixing of power sources offers a
utility company the flexibility to operate steam plants most efficiently as base plants while
meeting peak needs with the help of hydropower. This technique can help ensure reliable
supplies and may help eliminate brownouts and blackouts caused by partial or total power
failures.