This research evaluates the effect of leaking underground storage tanks (LUSTs) from gas stations on nearby commercial property when the existing data is incomplete or imperfect.? While methodologies such as hedonic regression may be preferred for evaluating the effects of LUSTs on property values, the rigorous data requirements of these methodologies often cannot be met.? Contingent valuation analysis is one method that enables estimation of losses when the data available is incomplete. A contingent valuation analysis of real estate professionals in South Carolina and Ohio provides estimates of commercial property losses, which ranges from 0-40%, depending on environmental conditions and proximity to the source. This research has developed a methodology for estimating real estate property value losses when data requirements cannot be fulfilled based on the best available data.