The case study examines the application of Geographic Information System (GIS) technology in the monitoring and evaluation of the construction of the flood control structure along the Principe River in Agoo, La Union, Philippines. The study explores how GIS contributes to improved project monitoring, resource allocation, environmental compliance, and risk management. Using tools such as ArcGIS and QGIS, GIS provided real-time visualization and site condition analysis that supported efficient decision-making and project implementation. Findings indicate that GIS enhanced resource utilization by identifying priority reinforcement zones and contributed to environmental sustainability by identifying ecologically sensitive areas. GIS also assisted in meeting project milestones by anticipating potential delays and supporting alternative workflow adjustments. However, high implementation costs and limited technical expertise were identified as constraints, underscoring the need for capacity building and cost‑efficient GIS solutions. The study employed a qualitative descriptive case study design, utilizing structured interviews and field observations with project engineers and GIS specialists involved in the project implementation. The findings highlight the transformative potential of GIS technology in infrastructure development, particularly in enhancing implementation efficiency, regulatory compliance, and risk mitigation in flood‑prone areas.