There's mounting political pressure to get more energy from alternative sources and developers are pushing ambitious projects to exploit America's biggest rivers for power.

A new generation of low-impact hydroelectric plants is expected to light up the Ohio River Valley.

The Ohio River is already home to 20 navigation and flood control dams. Six dams have been outfitted for hydro power and licenses have been issued for an additional four.

Jeff Hawk with the U.S. Army Corps of Engineers in Pittsburgh says the corps has seen a spurt of applications and is busier reviewing hydro applications than it has ever been.

Water is already the nation's leading renewable energy source for producing electricity.

Linda Church Coicci with the National Hydropower Association says once a hydro facility is built, operators don't have ongoing fuel costs.