<p>Sustainable groundwater management relies on a thorough understanding of the hydrogeological environment. Unfortunately, hydrogeological information is scarce in developing countries, yet very valuable, as groundwater often represents the most important water supply. This study investigates a catchment in Siguatepeque, Honduras. A steady-state numerical groundwater flow model was developed. Spatial, stratigraphic, and hydrogeological parameters were incorporated as input data. Groundwater recharge, groundwater abstraction, and river discharge were incorporated as fluxes to define the boundary conditions. Both manual and semiautomated calibration were performed on the basis of observed hydraulic heads and river discharge during the dry season, obtaining a normalized root mean square error of 9%. Model sensitivity analysis identified hydraulic conductivity and recharge as the most sensitive parameters. Finally, projection scenarios were simulated for the years 2030, 2040, and 2050 to assess the joint impact of population growth and climate change. By 2050 the model predicts a generalized decline of groundwater levels (by 85&#xa0;m on average), with significant impacts to most public wells which currently supply more than 70% of the Siguatepeque City’s total water supply during the dry season. Recharge from river percolation is expected to increase by 39% and consequently base flow to decrease by 72%. Additionally, the model predicts that, at least during the dry period, groundwater demand will not be fully met with a deficit of 19%. The model represents an initial effort to provide insights that can guide and support the planning and implementation of management strategies for the sustainability of the Siguatepeque Aquifer and potentially beyond.</p>