In response to scarce financial resources, economists have promoted the concept of benefit transfer as a cost-effective alternative to new nonmarket valuation studies. Recent discussion on benefit transfer for improved water quality has focused on recreational benefits. While useful, the discussion must now be expanded to include another key benefit from improved water quality: the reduction in risk to public health. This paper develops a protocol for benefit transfer of long-term health risk reduction and presents a case study for surface water contamination. Challenges such as the multiple sources of risk, the mortality and morbidity effects indicated by a variety of symptoms, the long latency period between cause and effect, and an individual's ability to privately or collectively reduce the probability or severity of the risk are discussed. ¿ American Geophysical Union 1994