Environmental Characterization and Impact of Domestic Wastewater Discharges on the Cesar River, Colombia

Abstract

This study evaluates the environmental and social impacts associated with domestic wastewater discharges from the El Salguero Wastewater Treatment Plant (WWTP) on the Cesar River in Valledupar, Colombia. A mixed-methods approach was applied, combining physicochemical and microbiological water quality analysis with environmental impact assessment (EIA) and community perception surveys. Monitoring campaigns were conducted in 2025 at three strategic sampling points (upstream, discharge point, and downstream) to determine spatial variations in water quality conditions. The parameters analyzed included pH, temperature, electrical conductivity, total dissolved solids, total suspended solids, biochemical oxygen demand, chemical oxygen demand, oils and grease, and total coliforms. Results indicated significant variations in water quality associated with the wastewater discharge, particularly in organic load and microbiological contamination. Although several parameters complied with national regulatory limits, elevated values of organic matter and microbial indicators suggest persistent environmental pressure on the aquatic ecosystem. The application of an EIA methodology allowed the classification and prioritization of impacts affecting water quality, aquatic biodiversity, and surrounding communities. Overall, the findings highlight the need to strengthen wastewater treatment efficiency and monitoring strategies to reduce environmental degradation and improve river health. This research contributes to the understanding of wastewater-driven pollution dynamics in tropical river systems and supports the development of sustainable water management strategies in urbanizing regions.