The western Canadian subarctic is a landscape in transition due to climate warming, changing streamflow patterns and thawing permafrost. Climate change is mobilizing vast stores of carbon previously held in permafrost and altering the flow of water from land to aquatic systems; these changes should fundamentally affect stream chemistry and ecology. Warming or changing flow regimes can alter the configuration of supra-permafrost taliks, which are pockets of perennially unfrozen ground in a permafrost environment; these have received limited attention for their potential role in facilitating movement of materials in permafrost-affected landscapes. Taliks provide connections between unfrozen areas of the soil during winter, which has the potential to alter the source and chemistry of flow to streams. Across many northern regions, the development and expansion of supra-permafrost taliks in the Taiga Plains and Taiga Shield may contribute to increased winter/spring flow. Although emerging research has documented a unique wintertime chemical signature indicative of talik flow, the specific influence of taliks during different seasons on subarctic rivers is poorly understood. Winter flow through taliks contributes to the development of icings, which are sheet-like masses of layered ice above the ground surface that can be used as an archival tool to study the chemical nature of winter flow. In this study we are investigating the biogeochemical effects of taliks within the River Lake and Baker Creek catchments near Yellowknife, NT. We performed detailed water sampling from April to June 2021. In March, we collected ice cores at five icings around River Lake, and an icing along Baker Creek to investigate temporal changes in talik water chemistry over winter. Chemical analyses of water and ice samples is underway and includes measures of DOC concentration and composition, nutrients, major ions, and trace metals. Biological processing is currently being assessed using incubation experiments to determine DOC loss over time. To understand how seasonal changes in water chemistry affect ecological function, microbial community structure will be assessed using 16-S-rRNA techniques. Early results show striking differences in water quality between thawed icing water and open water flow. These results will help inform predictions of how climate warming may change seasonal water chemistry at watershed and larger geographic scales.