We devise a simple model of intergenerational altruism under uncertainty. We present an estimable form of the model that relies on a few, plausible, assumptions. We apply the model to data collected in a survey of Southern Nevadans concerning the proposed Yucca Mountain Nuclear Waste Repository in Nye County, NV. We find strong evidence of a bequest motive. Approximately one third of the option wealth lost by households near the repository can be attributed to costs to future generations.