Eutrophication and proliferation of nuisance and harmful algal blooms, linked to excess phosphorus and nitrogen from agriculture and wastewater, are a global cause of water-quality impairment. In this presentation, we explore river eutrophication trajectories from a 150-year water quality dataset for the River Thames, London, England. Water-quality monitoring began ten years after the “Great Stink” of 1858, when the City of London and the Houses of Parliament came to a standstill as a result of the overwhelming stench from untreated sewage flowing unimpeded into the River Thames from a rapidly growing urban population. The Thames water-quality monitoring (1868 to the present day) provides an unparalleled historical biogeochemistry record, documenting the effects of social, economic and agricultural activity, and environmental policy on the river’s chemistry, quality and ecological function. Growing urban populations, the building of sewage ‘farms’ and subsequent improvements in wastewater management and treatment, the drive to increase UK domestic food security during the second world war, and agricultural intensification of the post-war years, have all left an indelible imprint on the hydrochemistry of the River Thames. Growing concerns about eutrophication in the 1970s and 1980s resulted in concerted efforts to reduce point-source nutrient inputs, and agri-environmental schemes to control non-point phosphorus and nitrogen sources. The 1990s brought new European Union (EU) water legislation: the Urban Wastewater Treatment Directive mandated tertiary phosphorus removal at large municipal sewage works and the Nitrates Directive improved management of manure and fertilizers applied to land. In 2000, the EU Water Framework Directive subsequently focused attention on watershed and river management measures needed to improve the ecological status of the River Thames. We examine the successes and challenges of these policies, the continuing legacies of past land use and management, and the implications for meeting nutrient criteria and addressing eutrophication within this iconic river.