Yamanomiya, Mountain Shrines of Mystery, has posted an article on the Kitakami River and its source, the Yuhazu spring in Iwate. The Yuhazu spring is on the grounds of the Mido Kannon Temple. This modest spring is said to be the source of the mightiest river in Tohoku.
Yamanomiya: Mountain Shrines of Mystery has posted a series of articles of shrines in Iwate Prefecture that enshrine the kami Seoritsuhime. She is the spirit of waterfalls and rapids, of purification and water in all its aspects.
Seoritsuhime was a kami who lived in Omi on the shore of Biwako, around 3,000 years ago, as documented in the Hotsuma Tsutae. Because she was an indigenous leader, the later continentals wished to erase her memory. They succeeded in reducing the number of her shrines from the thousands to a mere 450. See also the series of articles by Woshite World on why and how Wosite, the indigenous language, was erased as well.
Iwate Prefecture, with 36, has the most Seoritsuhime shrines. Yamanomiya visited and reported on seven of them.