• General water-quality regulations exist; there is no phosphorus-specific national policy.​

• Traditional limnological monitoring tools (e.g. total phosphorus, soluble reactive phosphorus, chlorophyll-a, Secchi depth).

• Agriculture and sewage inputs are major sources of phosphorus loading.

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• Buenos Aires Province runs an integrated cyanobacteria management programme, coordinated by the Under-Secretariat of Water Resources and the Water Authority (ADA). Fifty municipalities currently take part.

• Municipal visual monitoring with citizen science, laboratory analysis and remote sensing converge into the Cianosemáforo, a four-level risk traffic light published directly to the public and to municipal teams.

• Current regulations cover point sources and exclude diffuse loads, agricultural runoff and livestock, which dominate in these catchments, with no traceability or economic instruments to reduce them. Without active phosphorus management, monitoring sustains the alert but does not reverse the process.

• Phosphorus management is fragmented across water, wastewater, agriculture and ecosystem protection and conservation policies. There is no dedicated national phosphorus strategy. Eutrophication control and lake restoration strategies are site-based and project-driven.

• Basin Councils provide a regional space for multi-stakeholder coordination at catchment scale, although their role remains largely advisory and their authority is very limited.

• Funding for water quality management and lake restoration relies on a few federal programs, research grants, international cooperation and private foundations. Funding schemes rarely target phosphorus reduction.

• Brazil has no targeted phosphorus taxes or dedicated national eutrophication funds, however the National Policy on Payment for Environmental Services (PNPSA, Law 14.119/2021) presents an opportunity to engage stakeholders in the reduction of phosphorus loads.

• Effective phosphorus management support is constrained by the absence of dedicated phosphorus monitoring programs, standardized assessment methodologies, and integrated data systems.

• Management and decision-making remain inconsistent across regions. Watershed committees serve as platforms where cross-sector collaboration, monitoring, and engagement are conducted. Incorporating universities into the planning for phosphorus load reduction could be a strategic move.
  

• Colombia does not have any policy to address phosphorus management directly, but this is addressed indirectly in water quality and land use policies. Similarly, lake ecosystems and watersheds management are considered as a priority in the National Wetlands Policy but don’t have a specific policy addressing them.

• Critical aspects that contribute to poor phosphorus management are precarious wastewater management and poor agricultural practices, common in rural Colombia and sometimes in large urban centers.

• Strengthening monitoring systems, improving data accessibility, and developing phosphorus-specific policies are essential to enhance long-term water quality and ecosystem resilience.

• Uruguay has robust environmental regulations, monitoring systems, and technical expertise for phosphorus management, but these are spread across multiple institutions and have yet to be integrated into a unified national phosphorus strategy with clear targets and coordinated monitoring.

• In 2013, to address eutrophication and cyanobacterial blooms affecting the Santa Lucía River Basin, an Action Plan established an inter-institutional framework to mitigate nutrient inputs through targeted regulatory and non-regulatory measures.

• Advanced modelling and local action plans in priority water bodies, including the Casupá sub-basin and Laguna del Sauce, are being used to assess nutrient reduction measures, improve water quality, and manage pressures from agriculture, urban development, tourism, and wastewater discharges.