The water that flows through a dam spins turbine blades which are connected to high-powered generators that are placed within the dam. This creates power which is carried to homes and businesses.

Hydroelectric Power is believed to be the oldest form of generating power dating back to over 2,000 years ago. About 10 percent of the population in the United States has their power generated by hydroelectric power.

The advantages of hydroelectric power are that it creates minimal pollution to the air because fuel isn't burned, water is free and provided by nature, low cost to maintain, and it's renewable. The power is also available on demand because the flow of water to the generators can be controlled.

The disadvantages of hydroelectric power are that the dams can block fish passage which can decrease fish spawning and it can impact stream flow or even dry up a river bed entirely. It can also deplete the levels of dissolved oxygen in the water. The reservoirs can also be breeding grounds for undesirable growth and the spread of algae and aquatic weeds because of the build up of sediments and nutrients.