The ongoing and persistent drought in Central-western Argentina since 2010 is leading to a water crisis in the region. Despite the crucial importance of the Andean water resources for natural ecosystems and socio-economic activities few studies have focused on the relative contributions of snow and ice on the hydrology of the main regional watersheds such as the Mendoza River, which is the main water supply for the most extensive and densely populated irrigated oasis in central-western Argentina. To better understand snow and glacier temporal storage-and-release processes and its impact on the seasonal and inter-annual variability of the Mendoza Riverwe we provide an up-to-date modeling work using the numerical model HBV.IANIGLA which specifically incorporates separate snow and glacier components into the hydrological simulations. Modeled snow accumulation values show that the lower eastern sectors of the Mendoza watershed usually receive five times less snow than the westernmost areas bordering Chile. Model outputs from the adjacent Maipo and Aconcagua watersheds in Chile indicate almost 3.5 times more snow than the Mendoza River basin, corroborating the marked west-east precipitation gradient in this region. During the last 40 years, snow has been the main source of meltwater for the Mendoza river but glaciers have contributed, on average, ca. 18% of the annual discharges. Maximum values that exceed 40% in glacier contribution were modeled in years with very low winter snow accumulation. This is particularly evident during the extended dry period that started in 2010, when the glacier contribution averaged ca. 30% compared to ca. 15% prior to that period. These very dry years usually concentrate the bulk of the annual discharges later than normal during the warm melting season. These results provide an improved understanding of the surface water variability in this semiarid region for the last 40 years.