Suspension of sediment by subterranean springs is a very common phenomena in the karstic, multibasin Lake Banyoles. The flow of groundwater into the lake introduces a suspension of marly and argilaceous materials. The temperature of this slurry is nearly constant throughout the year, around 19 ¿C. The lake is formed by 6 basins and at the bottom of these basins there are 12 sources where the presence of suspended material signifies entering groundwater (Figure 1). Suspension of bottom lake sediment by groundwater is a feature of Lake Banyoles that has not been described elsewhere. Here we present experimental results which show that the maximum height that the sediment can rise to is affected by the formation of aggregates. ¿ American Geophysical Union 1996