This paper shows the results of a contingent valuation exercise carried out to assess the environmental impacts caused by the disposal of 56,000 tons of rock ash in the Dominican Republic in 2003 and 2004. In March 2007, the Dominican government and AES Corporation reached a legal settlement for US$6 million in penalties to avoid a lengthy legal process. The willingness to pay for a watching and monitoring program to prevent and mitigate environmental impacts caused by rock ash was estimated at US$194 million in 2007, reflecting the welfare losses experienced by the Dominican society at that moment.