The document discusses environmental economics and the valuation of natural systems using the concept of ecological services value (ESV). It defines key terms like total economic value and describes how ESV can provide a common metric to evaluate the stormwater impacts of development decisions. The research aims to develop a methodology and decision tool to calculate ESV based on stormwater modeling. Examples applying the ESV approach to residential and commercial development sites are provided. The tool is intended to help decision-makers compare economic and environmental factors.