Hydroelectric power generation has proven to be one of the most attractive energy sources available. Past energy shortages have spurred growth in the number of hydroelectric facilities and today, as never before, numerous existing and proposed sites for hydropower projects are being evaluated and developed. The unique advantages of hydropower over fossil fuel or nuclear-powered steam generation have significantly contributed to the enthusiasm for its use. Hydropower is presently meeting about 12 percent of our Nations energy needs. From the standpoint of energy resource conservation, hydropower is very attractive because the energy source water held in the reservoir is renewable. Hydropower is also extremely flexible from an operational standpoint. Hydropower is considered one of the cleanest major sources of electrical energy.