Data from years of monitoring of the SPM concentration is being investigated for possible evolutions of the physical system of the Sea Scheldt, with particular attention to the long-term evolution of the average SPM concentration. In the upper part of Sea Scheldt relatively higher concentrations of SPM are observed in the periods 1995-1997, 2003-2004 and 2009-2011. These periods coincide with years in which the freshwater discharge is rather limited. This confirms earlier observations in which higher SPM concentrations in the upper part of Sea Scheldt typically occur at periods with low freshwater discharge. In addition to increased SPM concentrations we observe in the upper part of Sea Scheldt also periods with relatively lower SPM concentrations. Thus, the period 1999-2001 is characterized by lower SPM concentrations. In these years freshwater discharge is significantly higher suggesting that discharge was sufficiently high to transport suspended sediment towards the sea. These findings emphasize the important role of freshwater discharge in development of an ETM in the upward parts of the estuary.