The most comprehensive study of Patos Lagoon was carried out by the 'Pró-Mar de Dentro' Project. During the period between February 1999 to January 2000, 11 sampling expeditions were performed, where 8 stations were established in the Patos Lagoon main axis, 3 stations on the main tributaries (Guaíba River, Camaquã River, and São Gonçalo Channel), and 1 station on the inner continental shelf, just after the Patos Lagoon inlet. During sampling procedures, a variety of chemical, physical, and biological parameters were analyzed. Data and results were reported in the year 2000 by a partnership with 'Japan International Cooperation Agency' (JICA), the project sponsor.