This study combines hydrological modeling with applied micro-econometric techniques to value a complex ecosystem service: drought mitigation provided by tropical forested watersheds to agrarian communities. Spatial variation in current baseflow allows estimation of drought mitigation values as the marginal profit accruing to agricultural households. The paper shows that this uncommon focus on producer (not consumer) surplus measures is appropriate for valuation as long as markets for commodities related to the environmental services are complete. For the typical household, the estimated marginal profit is positive, validating the central hypothesis that baseflow makes positive contributions to agricultural profits. There is some evidence, however, that increased watershed protection will increase profits through greater baseflow only in watersheds with a unique mix of physio-graphic and climatic features. The paper evaluates and provides some support for the hypothesis, put forward by hydrological science and the Indonesian Government, that protected watersheds can supply latent and unrecognized ecosystem services to local people.