Large and complex watersheds, as result of complex topography, characterize the Mexican landscape. And although water for human consumption is becoming more limited as water demands increase, there is incomplete information on current and future water availability. As water resources become scarce, it is not clear how ecosystem services of economic critical ecosystems will be impacted due to limited water supply in Mexico. The objective of this project is to evaluate how ecosystem resiliency capacity is controlled by the hydrological connectivity in a variety of Mexican ecosystems. The main goal is to assess the minimum water resources needed by ecosystems to provide critical environmental services to society. As a general approach we are evaluating water budgets in a variety of ecosystems ranging from semi-arid to tropical forest and coastal ecosystems. The research questions we are addressing are: What is the annual and inter-annual variation of water budgets? What type of natural and human disturbances controls the hydrological cycle? What are the human actions that most impact ecosystem hydrological function? What are the social perceptions by stakeholders related to the impact of human priorities in water use at the ecosystem level? To answer these questions we are using selected watersheds encompassing Mexican LTER study sites. We present preliminary analysis of selected budgets to illustrate a range of priorities in water use and allocation in terrestrial and coastal ecosystems.