To reduce pollution, the California Air Resources Board in 1996 required the reformulation of gasoline sold in California. In 1999, a series of disasters at California refineries substantially cut the supply of gasoline and contributed to large price increases. Environmentalists and California refiners (who had sunk large investments to produce the reformulated gasoline) opposed imports from other states, which would have kept prices down. To minimize fluctuations in prices in California, Severin Borenstein and Steven Stoft suggested setting a 15¢ surcharge on sellers of standard gasoline. In normal times, none of this gasoline would be sold, because it costs only 8¢ to 12¢ more to produce the California version. However, when disasters trigger a large shift in the supply curve of gasoline, firms could profitably import standard gasoline and keep the price in California from rising more than about 15¢ above prices in the rest of the United States. Use figures to evaluate Borenstein and Stoft's proposal.