Upper Midwest Environmental Sciences Center
Human activity (particularly agriculture) in the Upper Mississippi River Basin over the last 200 years has significantly altered the delivery of sediment and plant nutrients to the river. Modifications within the floodplain (e.g., dam and levee construction.) have also changed the processing, storage, and downstream transport of these materials.
The transport of sediment and major plant nutrients from upland areas to the Mississippi River Deltaand ultimately to the Louisiana Delta and the Gulf of Mexicohas major ecological and economic implications. For example, excessive nutrient export from the Mississippi River Basin to the Gulf of Mexico has been implicated in a growing zone of hypoxia in the Gulf.
In the upper river itself, sedimentation of backwater areas has been cited repeatedly as the most severe environmental problem. Excessive plant nutrients produce eutrophication (e.g., Lake Pepin) and likely contribute to recent changes in aquatic macrophyte abundance in the upper river.
To manage sediment and nutrients in the Upper Mississippi River and its catchment, the current situation (status), the historical perspective (trend), and mechanisms that control the movement of these materials (processes) must be understood.
This project is intended to (1) assemble and evaluate the existing information from various sources, (2) conduct analyses with the available information to provide best estimates of nutrient and sediment dynamics in this system, and (3) identify critical information gaps and set priorities for additional monitoring or research.
Major progress to date is the compilation of a database that contains nutrient and flow data for all major tributaries of the Upper Mississippi River. A Web page application (available at http://www.umesc.usgs.gov) provides access to these data, along with geographic information system data and figures. Maps displaying nutrient concentrations and yields are included. Research is under way to identify sources of nutrients, evaluate loading patterns, and develop nutrient criteria for the Upper Mississippi River Basin and US Environmental Protection Agency Region 5.
Presentations have been given at water resource-related meetings and conferences (e.g., American Society of Limnology and Oceanography, Upper Mississippi River Conservation Committee, US Environmental Protection Agency). The project was completed in September 2001.