It was estimated that the real amount of nitrogen load flowing into the rivers and lakes. Nitrogen load of 8.33 × 10⁵ [ty^-1] is generated from food supply and consumption processes in Japan, however, some part of the load is purified in the way to the rivers and lakes. The data compiled by the administration offices are employed in order to estimate the load generated from food production and consumption processes. The real load affecting the environment was estimated from water quality of the relatively large rivers. The ratio of the load flowing into the rivers to generated one is closely related with rainfall. Large rainfall gives higher ratio. The average ratio observed in Japan is 0.49, and the real amount of nitrogen load flowing into the rivers is estimated to be 4.05 × 10⁵ [ty^-1].