The current worldwide concern over energy is primarily related to imported oil, oil drilling and refining capacity, and transportation capacity. However, this concern has bolstered interest in a broader range of "green" energy technologies. In this article, the author discusses the use of hydroelectricity as an alternative energy source and examines its impact on the environment. An activity that challenges students to design a better water turbine in order to increase the power output of a small DC electric motor that is being used as a generator is included. (Contains 5 figures.)