Valuing water quality benefits from adopting best management practices: A spatial approach.

We developed a GIS-based tool that values, in a spatially explicit way, the ecosystem services generated by water quality improvements resulting from adoption of agricultural best management practices (BMPs). The tool is calibrated for watersheds in the Chesapeake Bay drainage and includes the benefits from water quality improvements within targeted watersheds, water quality improvements downstream from targeted watersheds, and reductions in pollutant loadings to Chesapeake Bay. The tool is used to investigate specific BMP scenarios adopted within specific watersheds. The results show that (i) BMP adoption generates large positive net benefits to society, with benefit/cost ratios ranging from 22 to 276; (ii) by selecting cost effective BMPs and placing them in the most appropriate places, the cost of meeting pollutant reduction targets would be reduced by 34-71%; and (iii) net benefits from BMP adoption are higher when they are implemented close to or upstream from population centers.