Abstract. Full text article available at https://doi.org/10.1007/s40899-020-00400-zWater resources such as lakes are important for sustaining human life and aquatic ecosystems, but a lack of understanding of pressures from anthropogenic activities and recurring floods and droughts can cause problems for communities and ecosystems because of their impact on lake size and water quality. This study aims to assess the impacts of anthropogenic and climate variation on the spatiotemporal pattern of Lake Babati in Tanzania by establishing physical trends over a period of more than four decades, and evaluate how land use/cover change and climatic variation influenced the pattern. The assessment was made using Landsat images acquired from the United States Geological Survey for the years 1973, 1986, 1991, 1995, 2000, 2005, 2010, 2015, and 2018; daily precipitation and temperature data spanning 1973–2018 sourced from the African Flood and Drought Monitor database, and augmented by field surveys of anthropogenic activities around Lake Babati Basin. Findings from this study revealed a fluctuation of lake surface area between 10.90 and 14.19 km2 over 45 years, partly attributed to rapid urbanization, agriculture and climate variation around the lake. The largest lake areal extent decrease of 2.72 km2 and largest increase of 3.29 km2 were experienced between 2000 and 2005 and 1995–2000, respectively. Enhanced understanding of lake size trends from these results and associated environmental threats can guide the implementation of community programs in the Lake Babati Basin. We recommend water resource management policy options that include awareness raising, diversification of income generating activities and enforcement of environmental laws.