The SARPOA dataset was created from the intention of establishing a model of interaction of nutrients and physical factors that conditioned plankton blooms in estuaries. During the two years of sampling efforts (August 1994, February and September 1995, and February 1996), 4 expeditions where conducted on board of the R/V Larus. Sampling cruises counted on 19 stations located from Rio Grande Channel to Guaíba River basin and its tributaries: Rivers Jacuí, Caí, Rio dos Sinos, and Gravataí. SPM samples were analyzed using protocols by Aminot and Chaussepied (Aminot, A. and Chaussepied, M.: Manuel des Analyses Chimiques en milieu Matin, CNEXO, Bres, p. 396, 1983). The SARPOA project was financed by the European Economic Community (BEL) with support from the University of Dundee (UK).