Water qualities of tributaries and dams of the Joganji-gawa River system (2016-2018)

Water qualities of tributaries and dams of the Joganji-gawa River system had been investigated during 2016 to 2018. When mixing ratios of three resources might be changed, chemical compositions of water of the irrigation canal Josaigokuchi-yousui were changed. Concentrations of odorous constituents such as geosmin at surface water of dams changed from 10% to 20% of the water quality standard for drinking water. Concentrations of these constituents in water of the irrigation canal Josaigokuchi-yousui were lower than that in dam water. Arsenic originated from old Kamegai mine was sometimes detected at Koguchigawa-dam, Wada-gawa River and Koguchi-gawa River with concentrations of under the water quality standard for drinking water. However, concentrations of lead originated from this mine in water suddenly increased at Koguchigawa-dam and Koguchi-gawa River and the concentration of lead in River Koguchi-gawa had been exceeded the water quality standard for drinking water only once during investigation period. Lead was not detected in water of irrigation canal Josaigokuchi-yousui during investigation period and arsenic was sometimes detected in water of this canal with concentrations from 10% to 20% to the water quality standard for drinking water in 2018. However, after water purification at the Nagaresugi Purification Plant of Toyama city, no arsenic and lead was detected.