In May of 2000, thousands of residents of the town of Walkerton, Ontario became ill from drinking municipal water contaminated by Escherichia coli and Campylobacter jejuni bacteria. Seven people died, while many suffered debilitating injuries. A highly unusual and risk prone local hydrological regime, coupled with manure spreading on farms near municipal wells, and lax oversight by municipal water utility officials, were quickly blamed by Ontario government figures, including then premier Mike Harris. However, the scandal surrounding Walkerton's tragedy and a subsequent public inquiry into the incident also implicated neoliberal reforms of environmental governance introduced by Harris's government subsequent to its election in 1995. This paper examines the Walkerton incident as an important example of a “normal accident” of neoliberalism, one that can be expected from neoliberal environmental regulatory reforms arising from systematic irresponsibility in environmental governance. This irresponsibility is promulgated by an overarching hostility to any regulatory interference with free markets, as well as specific regulatory gaps that produce environmental risks. The paper also serves as a case study of the extent to which neoliberalism is constituted by environmental governance reform, and conversely, how environmental governance reform is reconfigured as part of the emergent neoliberal mode of social regulation.