The most conspicuous waterbodies in the Pampa region of Argentina are the so-called ''lagunas''. A typical Pampean laguna may be described as a relatively large (100+ha), permanent, shallow lake. Here, we report the dynamics of laguna Chascomu´s, sampled weekly, from April 2001 to June 2003. During the period, the lakes experienced three consecutive floods waves that affected the concentration of major ions and the optical signature of the dissolved organic matter. Despite these hydrological alterations, laguna Chascomu´s was permanently limited by light. Transparency was to a great extent controlled by the incident photosynthetic available radiation irradiance. We hypothesize that wind contributes to the permanent mixing of the lake, as well as to lessen the sedimentation losses of photoautotrophs.