The wrong management of watering in the highest zones of the Mendoza northern oasis, the topography of the terrain and the deficient drainage, together with neotectonics phenomena, but mostly a dramatic and progressive increase of the Rio Mendoza flow volume originated the expansion of the wetlands area at the NE of the city of Mendoza at the turn of the 18th century, while in previous centuries it had retracted to a minimum. The area grew until reaching the dimension of large wetlands in the lowest oasis zones, resulting from a larger runoff and soil saturation by the rise of the phreatic layers. This situation remained throughout the 19th century, affecting the extension and use of the available land for human activity. The purpose of this study was to research this process that culminated in 1930 with the partial desiccation of the area. We have given particular importance to the influence of the climatic fluctuations in the Cordillera de los Andes and to the consequent variations of the Rio Mendoza flow volume in this process. For the analysis we used snowfall series at the cordillera and flow volume of the Rio Mendoza, built by Prieto (2009) with documental data. We analyzed which were the mediate and immediate consequences of the growth and later desiccation of the wetlands over the environment and its present repercussion on the ecosystem (salinization, poor soil drainage, soil alkalinization, sedimentation). In addition, we have also worked over georeferenced historic charts that partially reflect the behavior of the Cienaga del Bermejo during the 18th, 19th and 20th centuries. This behavior characterized by "growth pulses" and retraction moments is reflected in the analyzed charts, where those moments of major growth coincide with cycles of bigger snowstorms and larger flow volume in the Rio Mendoza.