The North-East region of Mexican Republic has a semi-arid weather condition; this area covers partially Tamaulipas,
Nuevo León and Coahuila states. Pablillo River Basin (PRB) is located close to Nuevo León south border and its
catchment area involves Linares City (LC), Hualahuises City (HC) and Cerro-Prieto dam (CP). This reservoir captures
drinking water to Monterrey Metropolitan Zone (MMZ) the major urban center on the north-east Mexican region. More
than 50% of the potable water for LC comes from groundwater stockpiles. A combination of GIS maps and major ion
chemistry analysis has been assessed, to know the origin, geochemical evolution, and hydraulic interconnection of
groundwater. During 2008-2009, 46 groundwater samples were taken and analyzed around LC and HC. GIS technology
was use to analyze the spatial distribution of the constituents of groundwater through thematic maps. The major ion
analysis and its results suggest the presences of two aquifers; shallow porous aquifer on the top and fractured aquifer on
the bottom. General water mineralization was discovered, including dissolution of halite, dolomites and carbonates
through the aquifers. Water quality varies widely through the aquifers, and the general pathways go from southwest to
northeast direction. The overexploitation of groundwater increases the water mixing of groundwater between shallow
and deeper aquifers. Natural origin of groundwater and groundwater pollution by anthropogenic activities should be
considered in the groundwater quality analysis for drinking water purpose.