Following an incident of serious river pollution from a disused mine, postal surveys of local residents were conducted approximately 6 wks (Time 1 [T1]; n = 536) and then 8 mo (Time 2 [T2]; n = 417) after the spillage. Questions assessed residents' evaluations of the severity of the pollution, trust in expert reassurances, attributions of responsibility, and attitudes on other environmental issues. Respondents at T1 were more pessimistic than those at T2 in their estimates of the levels of pollution that would persist 6 mo and 10 yrs later, whereas T2 respondents gave more negative estimates of levels of pollution that existed before and immediately after the spillage. T2 respondents were less inclined to assign personal responsibility for the incident. On both occasions, women gave higher estimates of pollution and were more prepared to assign blame than men. These ratings covaried with other environmental attitudes, especially relating to nuclear power. The authors argue that the perceived time course of environmental impact deserves further research attention, and conclude that these data support a conception of attitudes as structures of evaluative associations, stored in memory, that can guide interpretation of information in specific contexts.