The Tamagawa Hot Spring in Senboku, Akita Prefecture, Japan is the highest flow rate hot spring in Japan. Tamagawa Hot Spring has a flow rate of 150 liters/second. The Tamagawa Hot Spring feeds a 3 meter wide stream with a temperature of 98°C. The water from Tamagawa Hot Spring is also very acidic, with a pH of about 1.1. There is also radioactive radium gas and other radioactive materials dissolved in the water from Tamagawa Hot Spring. Tamagawa Hot Spring