The pump-generating plant in the Lewiston Dam is atypical, in that the dam was constructed not to control the flow of water in a natural river, but to contain a man-made , upper reservoir (named the Lewiston Reservoir) which stores the water before its release into the forebay of the Robert Moses Power Station. Water enters the forebay by tunnels from the Niagara River controlled by the International Control Dam upstream of the natural falls. Water in the forebay is then pumped up into the upper reservoir or immediately sent down over the escarpment downstream of the natural falls into the Robert Moses Power Station turbines. The Lewiston Pump-Generating Plant houses 12 electrically powered pump-generators that can generate a combined when water in the upper reservoir is released.