There is growing concern about the sustainability of freshwater ecosystems in northern Canada that are under significant stress from climate change, resource development, and hydroelectric development, among others. Community-based monitoring (CBM) based on traditional ecological knowledge (TEK) has the potential to contribute to understanding impacts on the environment and community livelihoods. This paper shares insights about culturally driven monitoring, through collaborative research with Kátł’odeeche First Nation (KFN) in the Northwest Territories. This research was initiated in 2018 to improve understanding of the changes occurring in the Hay River and Buffalo River sub-basins, which extend primarily across the Alberta and Northwest Territories borders. Drawing on 15 semi-structured interviews conducted with KFN elders, fish harvesters, and youth, this paper illustrates the kinds of social–ecological indicators used by KFN to track changes in the health of aquatic systems as well as the fishing livelihoods of local people. Utilizing indicators, fishers observe declines in fish health, water quality, water quantity, and ice thickness in their lifetime. Community members perceive these changes to be a result of the cumulative effects of environmental stressors. The indicators as well as trends and patterns being observed and experienced can contribute to both social learning in the community as well as the governance of the larger Mackenzie River Basin.