[Evolution of the nitrate content of drinking water in the Department of Yonne: new evaluation since 1975].

A perceptible increase in the grade of nitrates in drinking waters in the Yonne Country had been established from 1969 to 1975 and had formed the subject of a previous published work. The present issue gives details about the persuit of this research from 1975 to 1979. It appears from it that the increase in the grade of nitrates in drinking waters is definitely continuing in most areas from 1975 with the exception of Morvan and Senonais. In 1979, the highest average grades reached 37 mg NO3/1 (Plateaux de Bourgogne) and the lowest 7 mg NO3/1 (Morvan). The number of collectings where the grades exceeded 44 mg/1 is increasing: 8% in 1975, 21% in 1979.