<p>The Saïss Basin in Morocco, a vital groundwater source for agriculture, industry, and domestic use, is under increasing pressure due to overexploitation and contamination. To address the significant issue of agricultural and industrial pollution in this under-studied region, groundwater quality was assessed using a multi-indicator approach that integrates physicochemical analyses, GIS techniques, and multivariate statistical methods. To assess groundwater quality, a combination of groundwater pollution indices was used. The assessment was based on a thorough analysis of 125 groundwater samples collected in September 2023, which were subjected to rigorous testing for major ions, nitrates, and heavy metals. The results revealed that nitrate contamination levels exceeded WHO standards in 52% of the samples, with agricultural areas being the most affected. The nitrate pollution index (NPI) also indicated a significant impact in 15% of the Saïss Basin, where 18 wells were identified as unsafe for human consumption (NPI &gt; 2). Hydrochemical analyses showed that rock–water interactions, HCO₃–Ca–Mg dominance, and the influence of agricultural activities were the main factors shaping the composition of groundwater. Hierarchical Cluster Analysis (HCA), grouped the wells into three distinct groundwater quality zones: high-salinity areas potentially influenced by saline intrusion and overexploitation; areas with standard water quality under natural dominance; and areas where agricultural and industrial pollution is strongly dominant. Spatial contamination patterns were identified through GIS analysis, emphasizing the need for a targeted mitigation strategies and sustainable groundwater management in the Saïss Basin.</p>