In a world of incomplete markets for environmental goods, ex ante planned expenditures rather than ex post realized outcomes explain the values individuals attach to these goods. We use the distance function to develop restrictions from a model of ex ante consumer behavior involving these goods. A contingent valuation approach is then employed to estimate policy-relevant components of the ex ante economic values that recreationists attach to differing subjective probabilities of alternative atmospheric visibility levels at a wilderness location and at an urban location in Oregon. Marginal valuations of probability changes are similar at the two sites. Marginal rates of time preference for resolving uncertainties vary between 10 and 50 percent and are inversely related to education. Existence value averages 10 percent of total value, and evidence is mixed that site-specific values act as surrogates for general environmental preferences.