This research investigates how compounding dynamics of climate change, upstream hydropower development, and local water engineering interventions for agricultural production in the Vietnamese Mekong Delta are linked to the ongoing disruptions of waterflows and consequential water scarcity in-situ. The adaptive management concept was used to unravel how state-led policy directions from food security towards water security enable change in water management in responding to the water challenges. Empirical evidence suggests that water retention is deployed as a key priority to store as much water as possible for local agriculture-based development policies as well as for household water consumption. While policy learning is seen, questions remain about how this ad-hoc solution could help address the delta’s water insecurity in the long term. The research advocates that this effort should focus not only on diplomatic interventions into upstream climate-development complexities but also local water-livelihood politics.