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In this paper we present surface water oxygen (delta O-18), hydrogen (delta D) and inorganic carbon (delta C-13(DIC)) isotope data to gain a better understanding of the modern day hydrogeology of Cuatrocienegas Basin, a semi-arid region in northeastern Mexico. Our study focuses on 26 water samples collected in March 2008 to investigate: 1) current provenance and flow pathways of surface waters, 2) the use of stable isotopes in identifying water loss and environmental degradation, and 3) human influence on hydrogeology. delta O-18 for Cuatrocienegas water samples ranged from -7.99 to +4.97 parts per thousand (mean -5.23 +/- 3.13 parts per thousand), delta D from -54.8 to +0.3 parts per thousand (mean -42.4 +/- 14.4 parts per thousand), and delta C-13(TDIC) from -21.6 to -9.2 parts per thousand (mean -14.3 +/- 3.4 parts per thousand). Samples collected progressively away from their respective spring lines display increasing delta O-18 and delta D values. Isotope data suggest that where the residence time of the groundwater is long and/or the system is hydrologically open, delta O-18 may not be a reliable indicator of water loss and environmental degradation. Our data suggest the central cienega (area W(b)) is the most viable area for palaeoenvironmental study and long term monitoring is an essential tool in the identification of ecosystem damage and response, allowing for better future management of the complex and fragile CCB ecosystem. (C) 2015 Elsevier Ltd. All rights reserved.