Spatial and temporal variation of physicochemical parameters of Cisne reservoir were studied. A clear spatial pattern was observed between the tributaries and the reservoir, with the highest values of conductivity, alkalinity, pH, silicate and phosphate (SRP) in the tributaries. The incorporation of bicarbonate, silicate, SRP and other nutrients by littoral vegetation and the decomposition process of macrophytes could explain the spatial pattern and the temporal variation of the nutrients. The freshwater marsh situated between the tributaries and reservoir acts as sink for silicate and SRP. The temporal and spatial pattern of total phosphorus (TP) was correlated with suspended matter values. The low nitrogen concentration and the ratio of the inorganic nitrogen to SRP suggest that nitrogen is a limiting factor for primary production.