The Tanana River flows through Interior Alaska, a region characterized by discontinuous permafrost. Studies link degrading permafrost to increased winter river discharge due to increasing groundwater input. In winter, Interior Alaska rivers are exclusively fed by groundwater, which serves as an external source of heat. In fact, some portions of rivers fed by groundwater maintain thin ice throughout the winter, or remain altogether ice-free, despite very cold air tempe ratures. These ice conditions represent a significant danger to winter travellers that use rivers fo r wintertime travel, particularly in this largely roadless area. We developed a determinist ic model to explore how fluctuations in groundwater discharge control ice thickness on the Tanana River. The model allows us to examine how local changes in groundwater characteristics affect ice dynamics by addressing two questions: What are the dominant factors controlling seasonal ice dynamics on the Tanana River? What are the rates of change in ice thickness resulting from observed and projected changes in these factors? Ice melt is amplified by increa sed hydraulic gradient, increased groundwater upwelling, increased air temperature, increased groundwater temperature, or increased snow depth. A warming c limate in regions with discontinuous permafrost is expected to increase groundwater input into rivers, decrease the temperature gradient between the atmosphere and the ice/water interface, and increase snow depths. All these changes contribute to decreased ice thickness and thus more hazardous conditions for winter travellers. The model illustrates the physical mechanisms, which corroborate s reports from Alaskans that ice conditions have become more dangerous in the spring, and further suggests that permafrost degradation could contribute to the degradation of river ice in a warming climate.