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A collection of archived hydrographs for 28 ephemeral streams provided a unique opportunity to quantify hydrograph characteristics for channels of the arid/semiarid Southwestern United States. Recurrence of flow and volume calculated using annual maxima converge with those of the complete series by 7years, suggesting that records of annual maxima are sufficient for estimates of extreme event recurrence. The relationship between peak discharge and volume for a flow event cannot be tightly constrained without consideration of event duration. As a result, volumes V(T), for recurrence intervals T, cannot be estimated from corresponding peaks Qp(T). Instead, volume recurrence should be estimated based on the joint distribution of peak discharge and duration. Although the density governing event duration in these semiarid study regions decays as a power law with time, the authors could not identify a probability density that provides a good fit to volume magnitude. Deterministic relationships exist between peak discharge and volume for an event of a given magnitude for the Las Vegas, Nevada; Phoenix, Arizona; and Albuquerque, New Mexico regions.