Water security and agricultural productivity in the Vietnamese Mekong Delta are at risk due to several water-related issues, most notably saltwater intrusion. Using historical data from 2011–2018 at 21 monitoring stations, this study applied percentile-based spatial interpolation to map saltwater intrusion at the 1 percent, 10 percent, and 50 percent salinity percentiles. Results reveal that extreme events (1st percentile) affect 51% of the district’s area with salinity >4 g/L, while typical years (50th percentile) affect 16% of the area, with eastern communes most vulnerable. The current irrigation system, comprising 13.2 km of canals, 79.4 km of embankments, and nine sluices, remains incomplete, thereby limiting control of saltwater intrusion. A planned network of 33 sluices by 2030 aims to enclose the system, supported by tailored water management strategies, including sluice operations, water transfer via the Ba Lai River, and storage of 12 million m³ in canals. These measures could ensure freshwater availability for orchards and domestic use. The study underscores the urgency of finalizing infrastructure and planning storage zones to address dry season shortages, offering insights for sustainable water management in the Vietnamese Mekong Delta under climate change pressures.