Within urban system, there are relationships between the constituent elements, which function through the consumption of matter and Energy imported from the environment. This study reviews from the systems theory approach the decisions focused on pressing the environment through the El Zapotillo dam in the second most important metropolis in Mexico. The Entropy-Homeostasis-Negentropy model is used. The results obtained show that the decisions for the water supply of the metropolis are limited to short-term negentropies, both in the functioning and in the configuration of the surrounding systems. In this way, it becomes urgent to specify systemic actions that promote the Integrated Management of Water Resources (IWRM).