Surface water quality of the Magdalena River in the Colombian Caribbean: future solutions for treatment wastewaters.

The treatment of water quality has gained global importance due to the increasing pressure on freshwater ecosystems from anthropogenic activities. In this context, hydrological quality studies are essential to develop and implement new strategies for water resource management, particularly in port areas where industrial and urban pressures converge. This study presents a comprehensive multitemporal assessment of surface water quality in the Magdalena River near the Palermo Sociedad Portuaria (Colombia), integrating physical, chemical, and microbiological parameters from 2016 to 2023. Two monitoring points (P1 upstream and P2 downstream) were analyzed using a suite of pollution indices WQI, ICOMI, ICOMO, ICOSUS, ICOTRO, and ICOpH along with two-way ANOVA, Spearman correlation, and principal component analysis (PCA). The findings reveal significant temporal variations in water quality, with deterioration peaks linked to the rainy season, increased agricultural activity, and untreated wastewater discharges. The PCA identified three principal components explaining 46.56% of the total variance, highlighting the influence of biodegradable organic matter (BOD₅), oxidizable load (COD), oils and greases (FO), and coliforms as key pollution drivers. The WQI ranged from 0.46 to 0.65, reflecting moderate quality, while the ICOMO and ICOTRO indicated persistent eutrophic conditions and suspended solids contamination, particularly at P1. Although the ICOMI and ICOpH showed mostly low contamination levels, isolated peaks suggest the need for continuous surveillance. Despite its semiannual frequency and limited spatial coverage, the study provides a reliable long-term baseline for understanding water quality dynamics in port environments. It demonstrates the effectiveness of multivariate and index-based approaches in tropical regions, where integrated assessments remain scarce. The results underscore the importance of strengthening wastewater treatment, promoting sustainable agricultural practices, and expanding the environmental monitoring network. This research contributes to bridging knowledge gaps in the ecological management of fluvial-port ecosystems in Colombia. Future strategies should consider predictive modeling and community-based participation to ensure the conservation of the Magdalena River's ecological integrity and its critical role in biodiversity, livelihoods, and regional development.