The Western Sierra Madré constitutes a natural water tower for the whole of northern Mexico. Rainfall amounts and runoff coefficients have enabled it to provide water to its neighbouring arid and semi-arid areas. However, considerable degradation of the mountain landscape has been observed for some decades. Overgrazing and deforestation have lead to soil degradation that has resulted in hydrological changes, and particularly a reduction in soil water retention in the catchment areas. In addition, piedmont oases have been transformed into irrigated areas. The Laguna irrigated area is located at the outlet of the Nazas river in the plain, to the south of the Chihuahuan desert. This area suffers not only from a reduction in water supply, relating to the severe drought conditions (since 1992), but also from substantial over-consumption of water. The need to ensure the natural equilibrium, in both mountain and piedmont areas, and to achieve a sustainable farming system should help reinforce the current changes taking place in water management.