Holtwood, Pennsylvania
Unincorporated community
Holtwood Show map of Pennsylvania Holtwood Show map of the United States
Coordinates: 39°49′55″N 76°19′39″W / 39.83194°N 76.32750°W / 39.83194; -76.32750
Country	United States
State	Pennsylvania
County	Lancaster
Township	Martic
Area
• Total	0.72 sq mi (1.86 km2)
• Land	0.71 sq mi (1.85 km2)
• Water	0.0039 sq mi (.01 km2)
Population  (2000)
• Total	97
• Density	140/sq mi (52/km2)
Time zone	UTC-5 (Eastern (EST))
• Summer (DST)	UTC-4 (EDT)
ZIP code	17532
GNIS feature ID	1177240[1]

Holtwood is an unincorporated community in Martic Township, Lancaster County, in the U.S. state of Pennsylvania.

Holtwood is the site of the Muddy Run Pumped Storage Hydroelectric Power Plant (172 Bethesda Church Road West, Holtwood, PA 17532), along the Susquehanna River. It pumps water into a reservoir during off-peak hours and uses that water to generate electricity during peak demand hours; it produces over 1,000 megawatts (MW) of power.^[2] Until 1996, a village that was also named Holtwood was situated upon the ledge of a hill above where is now the hydroelectric reservoir Lake Aldred. Holtwood Village populated the families of workers at the PP&L maintained Holtwood Dam on the Susquehanna. At its peak, it reached a population of approximately 500 residents; however, by the early 90s, only about 3 people remained, including longtime Dam employee Gerald Erb, the final resident of the village.

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