Furukawa claimed that through the construction by the Mining Pollution Prevention Law by the Mining Pollution Investigation Committee (the first) and through the river improvement constructions of Watarase-gawa River carried out before the end of the Taisho period, the mining pollution issues 'were, more or less, solved' (from "History of 100 Years of Business from Foundation").
古河側の主張によれば、（第1次）鉱毒調査会による鉱毒防止令による工事と、大正時代までに行われた渡良瀬川の治水工事により、鉱毒は「一応の解決をみた」（『創業100年史』より）と述べている。