The present study about the limnologic state of La Estanca de Alcañiz has been made for the Area of Water Quality of the Hydrographic Confederation of the Ebro. After an intense study elaborated throughout year 2001, this work makes a pursuit of the aquatic systems related to La Estanca, during the time at which this one is more vulnerable to a possible proliferation of cianobacterias, during the months of August and September of 2002. It is tried to determine the origin of the excess of nutrients cause of blooms of seaweed.