Agradecimentos: The research was the result of a partnership between EESC-USP and the Autonomous Department of Water and Sewage (DAAE), supported by Artur Osório and Katia Castro de Matteo, in addition to the NEEA laboratory (EESC-USP), Sanitation Laboratory (EESC-USP), LQA (Unicamp), Physical-Chemical and Microbiological Laboratory (DAAE), and Fauna and Flora Management Unit (DAAE). In addition, the authors acknowledge the Environmental Engineering undergraduate students from the "Environmental Monitoring: Study cases" course: Akio F. M. Motoki, Alexandra B. A. Holanda, Caio M. Mukaeda, Carlos M. S. Carreira, Caroline F. Sella, Flaviano B. C. Ferreira, Gabriel N. Oliveira, Guilherme C. Felício, Julia M. Pereira, Luis H. S. Filho, Maria C. F. Chade, Mariana V. da Silva, Natália C. Gallo, Nivaldo K. Junior, Pedro S. de Carvalho e Stella M. Louzada. This work was supported by the Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP, Brazil, Process 2015/18790-3). Laboratory analyses were supported by the University of São Paulo (USP), the University of Campinas (Unicamp), and the Autonomous Department of Water and Sewage (DAAE – Araraquara) Ver menos

Abstract: Land use changes threaten the maintenance of water quality and challenge the management of tropical reservoirs. In particular, eutrophication alters several ecosystem functions and services, compromising multiple uses of water. For example, in the Lajeado Reservoir (Araraquara, São Paulo, Brazil), aquatic macrophytes rapidly spread and occupied more than 90% of the system’s surface area (from 2016 to 2019). In such a scenario, this research aimed to evaluate the eutrophication causes and impacts to provide technical and scientific support to public agencies and propose remediation alternatives. First, a diagnosis of the study area was performed, using available data on land use, water quality, and climate (between 2010 and 2018). Second, water and sediment samples were collected for physical, chemical, and ecotoxicological analyses. The Ecological Risk Assessment consisted of a triad of Lines of Evidence, including physical-chemical, chemical, and ecotoxicological results. The expansion of agricultural activities (e.g., sugarcane cultivation) and diffuse pollution were highlighted among possible causes, and water quality was affected by increases in the concentration of nutrients (e.g., nitrogen and phosphorus), metals (e.g., iron), and emerging contaminants (e.g., pesticides and caffeine). As a result, the Lajeado Reservoir presented a high ecological risk, and alternatives for macrophyte removal are needed. This research involved several stakeholders (i.e., community, government agencies, and universities) who participated more effectively in environmental monitoring and recovery Ver menos