The La Plata River Basin (LPRB) is the second-largest basin in South America, encompassing five countries: Argentina, Brazil, Bolivia, Paraguay, and Uruguay. It spans diverse regions, from the Andean mountains to the Pantanal wetlands, and from arid areas to the Pampas biome. Major cities are situated along the rivers, all facing different environmental pressures. Records of water quality assessments are scarce and fragmented, and there is no available comprehensive environmental quality study involving all five countries across the entire basin. Here we perform a bibliometric and science mapping analysis to describe the scientific knowledge and institutional collaboration of monitoring aquatic environments in the entirely basin. We searched and selected articles for each major river comprising the basin and with specific keywords related to monitoring and environmental assessments in two bibliographic repositories (SciELO and Scopus). There were 357 documents published in SciELO and 672 in Scopus on monitoring water quality in the LPRB from 1977 to 2023. Results show that there is limited information on the environmental quality aspects of the LPRB. No publications cover the entire basin and all five countries. Most studies have been conducted in the estuarine region and particular sub-basins of Brazil, Argentina, and Uruguay. Despite the studies on the basin for more than 5 decades, there is an urgent need to integrate the entire basin in research efforts to develop comprehensive monitoring programs for sustainable environmental management.