{"nrhp_refnum":"76002050","name":"Medina Dam","other_names":[],"category":"structure","location":{"address":"N of Castroville on the Medina River","address_restricted":false,"city":"Castroville","county":"Medina County","state":"TX","lat":29.540508980000027,"lon":-98.93425392899996,"geom_source":"nps_gis"},"listed_date":"1976-03-15","is_nhl":false,"nhl_designated_date":null,"areas_of_significance":["Community Planning and Development","Engineering","Architecture"],"significance_levels":["state"],"summary":{"what_it_is":"A concrete gravity dam on the Medina River about 40 miles west of San Antonio, near Castroville in Medina County, Texas, built 1911-1912 with a diversion dam four miles downstream and an irrigation canal system.","why_significant":"It was the first phase of a master plan to irrigate and develop farmland west of San Antonio, designed by engineer Fred Stark Pearson. When finished it was the fourth largest dam in the United States and the largest in Texas. It was also one of the earliest projects of its size in Texas financed by private capital, and it still supplies irrigation water.","narrative":"Medina Dam is a massive concrete gravity dam on the Medina River, roughly 40 miles west of San Antonio near Castroville. Built between 1911 and 1912 for an irrigation system created by engineer Fred Stark Pearson with British financing, it rises 164 feet above the riverbed and runs 1,580 feet from bluff to bluff. Its thickness tapers from 128 feet at the base to 25 feet at the top, and limestone boulders were embedded in the concrete to add bulk. A diversion dam four miles downstream sends water into about 300 miles of canals, flumes and ditches. On completion it was the fourth largest dam in the country and the largest in Texas. It was the first phase of a plan to settle and irrigate land west of San Antonio, and it was among the earliest projects of its size in Texas funded by private capital. The system still irrigates farms in three counties.","period_of_significance":"1900- (specific dates 1911-12)","architect_builder":"Fred Stark Pearson","architectural_style":null,"criteria":[],"status_note":"Described as in excellent condition with only minor repairs to stop seepage; the whole system is in operation, irrigating fields in Bexar, Medina and Atascosa counties.","vacant_flag":false,"machine_generated":true,"model":"claude-sonnet-5-5","prompt_version":"v1.0-2026-10-29","generated_at":"2026-10-29 02:54:18.962782-05","source_pdf":"https://s3.amazonaws.com/NARAprodstorage/opastorage/live/20/9730/40973020/content/electronic-records/rg-079/NPS_TX/76002050.pdf"},"photo":{"url_800":"https://nationalhistoricalregister.com/media/76002050/3ad5b768d7-800.webp","url_1600":"https://nationalhistoricalregister.com/media/76002050/3ad5b768d7-1600.webp","licence":"CC BY 4.0","author":"Larry D. Moore","credit_html":"<a href=\"https://commons.wikimedia.org/wiki/File:Medina_dam_2010.jpg\" rel=\"noopener\">Larry D. Moore</a>, <a href=\"https://creativecommons.org/licenses/by/4.0\" rel=\"license noopener\">CC BY 4.0</a>, via Wikimedia Commons","source_page":"https://commons.wikimedia.org/wiki/File:Medina_dam_2010.jpg"},"district":null,"sources":{"nps_snapshot_date":"2026-05-22","nara_catalog":"https://catalog.archives.gov/id/40973020","wikipedia":"https://en.wikipedia.org/wiki/Medina_Dam","wikidata":"https://www.wikidata.org/wiki/Q6806915"},"indexable":true,"url":"https://nationalhistoricalregister.com/texas/medina-county/medina-dam-76002050/"}