The maintenance costing method is used to assess the cost need to reduce environmental degradation. This method's estimation concept involves confirmation of pollutants included in assessment, estimation of pollutant emissions, confirmation of the most effective control technologies for each pollutant (i.e., the best available technologies), calculation of the unit cost of controlling each pollutant (unit reduction cost), and finally multiply the unit reduction cost by the final volume of emissions to be reduced (i.e., emissions volume after taking carrying capacity into consideration), which yields the total maintenance cost.