Sources and transport of sediment, nutrients, and oxygen demanding substances in the Minnesota River Basin, 1989-92

The source of suspended sediment, major nutrients, BOD, and organic carbon in the Minnesota River.The effects these sources have on water quality in the Minnesota River.The relationships between suspended sediment, major nutrients, BOD, algal productivity, and organic carbon.The transport of suspended solids, nutrients, and oxygen demanding substances in the Minnesota River.The relative significance of instream sediment sources and non-point sources of pollution. It was determined that run-off was the major source of suspended sediment and nutrients in the Minnesota River mainstem. All the major tributaries were found to be contributors to the loading of nitrates, phosphorus, and suspended sediments. Tributaries in the South-Central and eastern parts of the Minnesota River Basin were found to produce the highest levels of loading due to higher precipitation and run-off. Suspended sediments were found to be mainly composed of silt and clay size particles. Phosphorus and nitrate concentrations were found to be enriched throughout the basin with nitrate concentrations being highest in the South-Central and Eastern parts of the basin. Oxygen demand was found to be highest during periods of summer low flow. Sediment and nutrient transport was found to be conservative. During all but the periods of lowest flow nutrient inputs were found to greatly exceed biological utilization.