[1] The spring contains hydrochloric acid as a main component, along with carbon dioxide, iron, and aluminum-chloride.

[2] Hokutolite is composed of a type of barite (barium sulfate), including lead and traces of strontium and calcium, and is about ten times as radioactive as the standard background radiation.

[4] The springs were discovered by a local matagi hunter in 1680, but the area was used primarily as a sulfur mine and it was not until 1885 that the first lodging was erected.

Due to the isolation of the site, it could only be reached on horseback with some difficulty until after World War II.

[5] There are two lodging facilities available in the area, Tamagawa Onsen, an inn located near the spring (opens from mid April to December, and closed for winter since 2012 due to the avalanche on February 1, 2012, which killed 3 people), and Shin-Tamagawa Onsen, a hotel about a kilometer down from the spring which opens year-round, run by the same owner of Tamagawa Onsen inn.