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.
The supplementary data is available from https://doi.org/10.6084/m9.figshare.8050544 .
常願寺川水系の支流やダム湖とそれらの水を集めた常西合口用水の水質を2016年~2018年にかけて調査した.常西合口用水の基本水質は水系内に3系統ある水源(有峰系,横江系,称名・真川系)の混合比によって変化した.ダム湖表層水中のジェオスミンなどの臭気成分濃度は水道水質基準の10~20%の範囲で変化した.また,常西合口用水の臭気成分濃度はダム湖表層の値よりも低かった.
立山の地獄谷から湧出する強酸性の温泉に含まれている水銀やヒ素などの重金属類は,称名滝下流の飛龍橋に到達するまでに自然除去されていた.また,旧亀谷鉱山起源と考えられるヒ素は,小口川ダム,和田川,小口川で,時々検出されたが,水道水質基準濃度以下であった.また,同鉱山起源と考えられる鉛は,小口川ダムや小口川で濃度が突然上昇する場合があった.なお,浄水処理後の水では鉛もヒ素も検出されなかった.