Hydro Hall of Fame: Taking Holtwood Next into the Century For 100 years, the 108-MW Holtwood hydroelectric plant has generated clean, renewable energy for businesses and residents in south central Pennsylvania. This facility, now owned by PPL Holtwood, uses the power of the water held back by a 55-foot-high dam across the Susquehanna River between Lancaster and York counties. Read more on Renewable Energy World