Suspended sediment dynamics of a riverine lake of the St. Lawrence River, Canada. Erosion and sediment monitoring programmes in river basins

Discharges and sediment loads were measured on the St Lawrence River at the inlet and outlet of Lake St Pierre, and at the mouths of the four main tributaries to the lake. During the period of summer low flow, there was a net export of suspended sediment from the lake by the St Lawrence River. Exceptions occurred for short periods when high flows, caused by rainstorms, transported more suspended sediment into the lake than the river exported. The net sediment export is the result of the export from the lake of sediment carried there during the spring melt. The suspended load of the tributaries is of a constant concern for water quality in the river, during spring melt when tributary sediment loads are high, and during summer when suspended sediment originally derived from the tributaries is remobilized in the lake and transported downstream by the river.