Hydropower is one of the oldest forms of energy harassed; it remains the largest section of the renewable energy pie in the United States at about 7% of total energy production. This accounted for nearly 70% of all renewable energy produced in 2010. While this is still a significant percentage of total energy produced, it has declined from the prominence it once had as concerns of the adverse environmental impacts of dams have risen. Some existing dams may be dismantled because of these adverse impacts, yet there is still much undeveloped potential for energy production. Much of this new potential has arisen from newer pumped storage and alternative hydrokinetic technology generators, which allow electricity capture from waves, tides, or in-stream flows.