The concept of water security encompasses dynamic objectives in various socio-hydrologic contexts. This study examines the pressures on several dimensions of water security and water usage in an Andean basin utilizing an integrated water security index (IWS), the Water Evaluation and Planning System (WEAP) model, and 10 composite scenarios for the period 2021–2099. The results show 60% of the scenarios result in a "fair" IWS score, with 40% classified as "good" trending towards "fair" coverage. Competition in terms of demand coverage for equal and different water usage priorities indicates that mining, thermoelectric, and service-related uses cover their needs, whereas other human uses are unable to cope with the demand, domestic use being the most affected. The findings highlight the difficulty of ensuring water security for all users and reveal that population dynamics and controlled human interventions and trade-offs will have a substantial impact on the provision of water services.