This project shall be conducted for the purpose of promoting the implementation of countermeasures and plans for nitrate nitrogen control. In this project, project sites have been chosen among the areas where nitrate-nitrogen groundwater contamination was found. In each project, the causes of the pollution and the contribution rate of each causes of total was identified and feasible control measures for nitrate-nitrogen sources was formulated and implemented. The appropriate surveys necessary for the quantitative prediction and evaluation of the effectiveness of the countermeasures taken or planned.