For many years the government had been explaining that the works by the preventive measure and the renovation on Watarase-gawa River which was completed 1927 (see below) had solved the mining pollution, however, in the Environmental White Paper of 1993, they admitted that the then measures had been not enough to solve the fundamental issues.
政府は長年、この予防令による工事と、後述する渡良瀬川の改修工事（1927年竣工）で鉱毒問題は解決したとしてきたが、1993年、『環境白書』で、当時の対策が不十分で、根本的な解決とはならなかったことを認めた。