Sugar cane and cassava production use fertilizer (Table 3), herbicide and pesticide in stage of growing to get high yield. This study considered the effect of nitrogen fertilizer and it is calculated based on the average areas of crops harvesting (Table 4, 5). The environmental impact on the use of other nutrients, herbicide and pesticide has not been analyzed. Nitrogen can leach from the field to water which will have a direct impact on water quality. The leaching run off fraction is assumed to be 10% [1]. The maximum acceptable concentration for nitrate in drinking water quality standard is 10 mg/l and calculated volume water for dilution [1].