This paper discusses three criteria for evaluating the performance of water resource systems: reliability, resiliency, and vulnerability. These criteria describe the likelihood of system failure (reliability), the speed of recovery from failure (resiliency), and the severity of failure consequences (vulnerability). These measures are useful for evaluating and selecting alternative designs and operating policies for water resource projects. The paper illustrates their use through a case study of a water supply reservoir with various operating policies. Reliability is defined as the probability that a system is in a satisfactory state. Resiliency is the inverse of the expected time a system remains unsatisfactory after a failure. Vulnerability is the expected maximum severity of a failure. These criteria are based on the assumption that the performance of a water resource system can be described by a stationary stochastic process. The paper also discusses the trade-offs among reliability, resiliency, and vulnerability. For example, high reliability may come at the expense of high vulnerability. The paper provides an example of a reservoir operation problem, where different values of a parameter β were used to derive different operating policies. The results showed that as β increases, the penalty on large deficits becomes more severe, leading to lower reliability but higher resiliency and vulnerability. The paper concludes that there are trade-offs among expected benefits, reliability, resiliency, and vulnerability. Using these three risk criteria improves our ability to describe how often failures may occur, how long periods of unsatisfactory performance are likely to last, and how severe failure might be. The paper emphasizes the importance of considering these criteria in water resource system design and planning. It also highlights the need for engineers and planners to develop appropriate quantitative risk criteria that describe the undesirable events that individuals may experience as a consequence of particular investment or operating policy decisions.This paper discusses three criteria for evaluating the performance of water resource systems: reliability, resiliency, and vulnerability. These criteria describe the likelihood of system failure (reliability), the speed of recovery from failure (resiliency), and the severity of failure consequences (vulnerability). These measures are useful for evaluating and selecting alternative designs and operating policies for water resource projects. The paper illustrates their use through a case study of a water supply reservoir with various operating policies. Reliability is defined as the probability that a system is in a satisfactory state. Resiliency is the inverse of the expected time a system remains unsatisfactory after a failure. Vulnerability is the expected maximum severity of a failure. These criteria are based on the assumption that the performance of a water resource system can be described by a stationary stochastic process. The paper also discusses the trade-offs among reliability, resiliency, and vulnerability. For example, high reliability may come at the expense of high vulnerability. The paper provides an example of a reservoir operation problem, where different values of a parameter β were used to derive different operating policies. The results showed that as β increases, the penalty on large deficits becomes more severe, leading to lower reliability but higher resiliency and vulnerability. The paper concludes that there are trade-offs among expected benefits, reliability, resiliency, and vulnerability. Using these three risk criteria improves our ability to describe how often failures may occur, how long periods of unsatisfactory performance are likely to last, and how severe failure might be. The paper emphasizes the importance of considering these criteria in water resource system design and planning. It also highlights the need for engineers and planners to develop appropriate quantitative risk criteria that describe the undesirable events that individuals may experience as a consequence of particular investment or operating policy decisions.