This paper uses standard event-study methodology to analyze the effect of announcing disinvestment or withdrawal of U.S. firms from South Africa during the 1980s on those firms' returns. Several different measures of abnormal return indicate a consistent and significant positive announcement effect, particularly for the two- and three-day periods surrounding the public announcement. With one exception, these results hold even when the variables are normalized by their respective standard deviations to account for possible changes in variance due to the announcement. Using the "ordinary cross-sectional" test statistic rather than the usual t-statistic explicitly accounts for a change in variance at announcement throughout the analysis. Copyright 1997 Western Economic Association International.

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Source control costs for deep percolation emissions from irrigated agriculture are analyzed using a farm‐level model. Crop area, irrigation system and applied water are chosen to maximize the net benefits of agricultural production while accounting for the environmental damages and disposal costs of those emissions. Deep percolation is progressively reduced as environmental and disposal costs are increased. This occurs primarily through the adoption of more efficient irrigation technology and reductions in applied water for a given technology Higher surface water prices, such as through irrigation reform and constrained surface supplies, are additionally considered in light of the drainage problem, as are the effects, both short‐ and long‐term, on ground water use.