Many watersheds around the world are going through the process of suburbanization – the gradual change from primarily forested to increasing urbanization and development. In combination with shifting seasonality due to global change, freshwater ecosystems are experiencing a myriad of changes. Here we investigate the shifting phenology of surface water chemistry and nutrient availability in a temperate and suburbanizing watershed. We explore both long-term interannual changes as well as seasonal changes in concentrations of dissolved organic matter, inorganic nutrients, salts and major ions across 20 to 25 years (1999-2024) of data. The study reveals that flow-weighted concentrations of chloride, sodium, magnesium and calcium increased over time while concentrations of inorganic nitrogen (nitrate) declined over time. The long-term decline in nitrates appears to be influenced by changes in winter concentrations, in particular. Decreasing trends were also found for dissolved organic carbon an unexpected result given the predominance of wetlands with the catchment. In contrast, phosphorus (measured as PO43--P) exhibited an increasing trend. No significant changes were detected for concentrations of potassium, dissolved organic nitrogen, and ammonium. However, we also observed seasonal dynamics in ammonium with decreasing variability over time and especially in winter. Many of our observed changes are consistent with the freshwater salinization syndrome highlighting the importance of long-term data records that can integrate hydrological, ecological, and geological principles. By employing a multi-solute approach, we can develop a more holistic understanding of the process of suburbanization amidst global environmental changes.