Pumped storage hydroelectric project. Reservoir and electrical power transmission cables at a pumped storage hydroelectric project in the Rocky Mountains. During periods of lower electricity demand, water is pumped to a second reservoir higher in the mountains. When demand increases, the water returns to this lower reservoir through a turbine which generates electricity. This is Xcel Energy's Cabin Creek pumped storage hydroelectricity project. Photographed in July 2015, near Georgetown, Colorado, USA.