{"nrhp_refnum":"90000701","name":"Warrior Ridge Dam and Hydroelectric Plant","other_names":[],"category":"district","location":{"address":"2 mi. S of Petersburg, along Conrail main line","address_restricted":false,"city":"Petersburg","county":"Huntingdon County","state":"PA","lat":40.54034952900005,"lon":-78.0341731059487,"geom_source":"nps_gis"},"listed_date":"1990-04-26","is_nhl":false,"nhl_designated_date":null,"areas_of_significance":["Engineering","Industry"],"significance_levels":["local"],"summary":{"what_it_is":"A hydroelectric dam and power plant complex with a company-built operators' village in a gap of Warrior Ridge, on the Frankstown Branch of the Juniata River between Petersburg and Huntingdon, Huntingdon County, Pennsylvania. The main dam was built in 1905-07 for the Juniata Hydro-Electric Company of Philadelphia.","why_significant":"The nomination argues the complex is significant as an early prototype of buttressed hollow-core dam design by Ambursen, one of the earliest covered examples of that type, which drew wide attention in the engineering press. It is also presented as an intact industrial complex with its associated company housing, and as the first and only large-scale electricity production in Huntingdon County at that time.","narrative":"Warrior Ridge Dam and hydroelectric plant sits in a gap between two ridges of the Allegheny Mountains on the Frankstown Branch of the Juniata River, Huntingdon County. The main dam, a 400-foot reinforced concrete hollow dam about 27 feet high, was completed in 1905-07 for the Juniata Hydro-Electric Company of Philadelphia, with an auxiliary dam of similar design built in 1907. Ambursen Hydraulic Construction Company designed and built the dam, using a buttressed hollow-core form it had patented in 1904. William H. Cushman, the company's chief engineer, designed the power house. The plant had a rated capacity of 8000 horsepower and supplied power to Huntingdon, Altoona and Tyrone. The nomination treats the dam as an early prototype of its type and the complex, including four company houses built in 1907 for operators, as an intact example of an industrial facility and its community. A major part of the powerhouse was demolished in 1978.","period_of_significance":"1905-1939","architect_builder":null,"architectural_style":null,"criteria":["A","C"],"status_note":"A major portion of the power plant was demolished in 1978; the Agnes Flood of 1972 destroyed its turbines; the substation is in use; repairs since 1985 included new generators and a transformer.","vacant_flag":null,"machine_generated":true,"model":"claude-haiku-5-5","prompt_version":"v1.1-2026-10-29","generated_at":"2026-10-29 17:11:36.935267-05","source_pdf":"https://s3.amazonaws.com/NARAprodstorage/lz/electronic-records/rg-079/NPS_PA/90000701.pdf"},"photo":{"url_800":"https://nationalhistoricalregister.com/media/90000701/97b8167cbc-800.webp","url_1600":"https://nationalhistoricalregister.com/media/90000701/97b8167cbc-1600.webp","licence":"Public domain","author":"Jet Lowe","credit_html":"<a href=\"https://commons.wikimedia.org/wiki/File:Warrior_Ridge_Dam_and_Hydroelectric_Plant.jpg\" rel=\"noopener\">Jet Lowe</a>, Public domain, via Wikimedia Commons","source_page":"https://commons.wikimedia.org/wiki/File:Warrior_Ridge_Dam_and_Hydroelectric_Plant.jpg"},"district":null,"sources":{"nps_snapshot_date":"2026-05-22","nara_catalog":"https://catalog.archives.gov/id/71993065","wikipedia":"https://en.wikipedia.org/wiki/Warrior_Ridge_Dam_and_Hydroelectric_Plant","wikidata":"https://www.wikidata.org/wiki/Q7970784"},"indexable":true,"url":"https://nationalhistoricalregister.com/pennsylvania/huntingdon-county/warrior-ridge-dam-and-hydroelectric-plant-90000701/"}