Implementing best management practices (BMPs) can reduce nitrate concentration in groundwater, but does it pay to invest in programs that reduce nitrate by encouraging increased adoption of BMPs? In this paper we evaluate water quality improvement by benefit-cost analysis of adopting BMPs under such a program. The analysis shows that under current levels of contamination, costs of the program to foster BMP implementation will be equal to annually accrued benefits over a period of 6 years. However, under the worsening scenarios of increased nitrate-N concentrations, the same costs will be equal to the benefits in a 4- to 5-year period. If water quality improves to acceptable levels through adoption of BMPs, the results reveal that in the long run, investing in a BMP program will be more cost effective to reduce contamination than to seek alternative sources of safe drinking water supplies. ¿ 1998 American Geophysical Union