During the following day, when electrical demand is high, water is released from the upper reservoir through the pump-generators in the Lewiston Dam. The water flows into the forebay, where it falls through the turbines of the Moses plant. Some would say that the water is "used twice". This arrangement is a variant of pumped-storage hydroelectricity. Engineers copied what had been built by Ontario Hydro, across the river, when a similar system was built during construction of the Sir Adam Beck Generating Station II in the 1950s.