Shuixian origin: Shuiji, Xiaohu or Jian'ou?
All accounts point to Dahu (大湖) and the Zhuxian site on Yanyi mountain, but name the place differently. The 1929 Jian'ou gazetteer files it under Jian'ou's Heyi li. Baidu Baike says both 'Xiaohu township, Jianyang' and 'Shuiji township, Jianyang'. The Jianyang government now writes 小湖镇大湖村. The differences follow boundary changes: Shuiji county was abolished in 1956 and its towns, including Xiaohu and Shuiji, went to Jianyang. Jian'ou is today the main Minbei Shuixian producer and is sometimes treated as the home of the cultivar. Chinese Wikipedia adds an unsourced claim that the tree grew around Jianyang and Jian'ou a thousand years ago and was cultivated from the Kangxi era. Treat the 1821 date as traditional.