Once Upon an Oldman is an account of the controversy that surrounded the Alberta government's construction of a dam on the Oldman River to provide water for irrigation in the southern part of the province. Jack Glenn argues that, despite claims to the contrary, the governments of Canada and Alberta are not dedicated to protecting the environment and will even circumvent the law in order to avoid accepting responsibility for safeguarding the environment and the interests of Native people.

Glenn describes the geography and history of the Oldman River basin, the institutional arrangements behind the dam project, and the ongoing controversy as it has unfolded since 1976. He then takes a close look at the disparate groups involved in the controversy: the governments of Alberta and Canada and their agencies, the Southern Alberta Water Management Committee, the Friends of the Oldman River Society, and the Peigan Indian Band. Considering these in the context of major issues raised by the project, he discusses water management and irrigation, environmental impacts, and implications for the culture and beliefs of the Peigan, including their claim to a share of the flow of the river.

In Once Upon an Oldman, Glenn has pulled together information from a wide range of sources: the media, correspondence of politicians and public servants, reports from government agencies, environmental groups, and the Peigan Indians, court decisions, and interviews. What emerges is a disturbing and fascinating tale of confrontation, pitting governments against environmentalists and Native people, that convincingly demonstrates that resorting to the courts is an ineffective way to protect both the environment and those who have lived here since before the arrival of Europeans.