Contemporary observations suggest that water may disappear entirely from portions of some North Slope stream-beds during periods of drought or low flow. Climate models project even drier summers in the future. This could pose a problem for migrating fish that must be able to move back and forth from breeding and summer feeding areas to scarce overwintering sites. This work uses the best available long-term hydrologic data set for the North Slope (in the upper Kuparuk River watershed) to develop a model to assess the vulnerability of stream systems to periodic drought, and the vulnerability of migrating fish to a loss of stream connectivity.