The overabundance of nutrients (phosphorus, P, and nitrogen, N) in rivers and lakes poses a serious threat to water quality and water security globally. In particular, small streams within dominantly agricultural, mixed land-use watersheds are especially vulnerable to eutrophication due to multiple and interacting non-point agricultural nutrient sources (e.g., fertilizer, manure) and cumulative impacts of wider watershed nutrient sources (e.g., farmyards, rural wastewater discharges, sewage septic systems, nutrient legacies etc.). In this presentation, we examine the spatial and temporal patterns in N and P fractions from the upper and lower reaches of the Nith River watershed, Ontario, Canada. The Nith River is a significant contributor of nutrient and sediments to the Grand River and the eastern Lake Erie basin downstream, which is experiencing more frequent and intense algal blooms. It has been identified as a key priority watershed for water quality improvements and conservation practice adoption. Multivariable, weekly water quality monitoring, paired with a publicly available 50-year baseline (monthly) water quality dataset, sheds recent and historical insights on the long-term, seasonal, and flow-driven nutrient dynamics along the river continuum. Analytes included within these datasets include nitrate, ammonium, total P, soluble reactive P, and chloride. From upstream to downstream, N, P and Cl concentrations demonstrate different relationships with discharge, reflecting different nutrient sources, pathways, and hydrologic variability throughout the watershed. N and P concentrations regularly exceed Canadian water quality guidelines over the decades. In order to protect water quality and ecological functioning of small agricultural streams, especially under a changing climate, there is a significant need to better understand eutrophication risk along the land-to-lake continuum. The project findings have wider relevance within other agricultural-dominant watersheds and provides additional context on targeting conservation practices for nutrient load reduction.