Abstract: Explained herein is a method and equipment whereby windmills are used to directly propel water pumps to lift water from a lower elevation body of water to a nearby higher elevation body of water, where it is stored as potential energy.In one application of this method, one or more water pumps, each powered directly by a windmill, lift water from downstream of a river, stream, or creek to upstream of a dam at which a hydropower plant is installed. The windmill may be of the vertical-axis or horizontal. Upon demand, the lifted water is used to generate electricity utilizing the hydropower plant. An adjustable weir is constructed across the river, stream, or creek downstream the windmill, whose function is to create a reservoir or pool from which water can be pumped and to regulate the flow of water downstream. The adjustable weir can be raised or lowered by means of a jack or jacks that are controlled by a computer.