This research gives an overview of the status of water resources in the western Aosta Valley (Italy). Surface water, groundwater and precipitation were sampled during five sampling campaigns, and chemical analyses were performed and interpreted. Stable isotopes (δ18O and δ2H) were evaluated. This study highlights the relationships between water quality and quantity and local conditions (i.e., aquifer lithology, mixing into the aquifer, proximity to towns, contribution of snowmelt and ice melt to groundwater recharge, amount of rain, and season and altitude of the sampling location). A relationship between dust dispersed in the atmosphere as aerosols from the nearby Piedmont Region and the precipitation chemistry was identified, highlighting the presence of interregional conditions. Furthermore, isotopic analyses allowed the identification of aquifer feeding by both rainwater and glacial meltwater. Additionally, two origins for rainfall were identified: the Mediterranean Sea in winter and the Atlantic Ocean in summer. Finally, a local meteoric water line was calibrated for the study area. This research highlights the importance of implementing both traditional and isotopic techniques for water analysis to achieve optimal and sustainable management of water resources.