Hypoxia in the Gulf of Mexico
A Science Assessment was conducted under the auspices of the National Science and Technology Council’s Committee on Environment and Natural Resources at the request of the Mississippi River/Gulf of Mexico Watershed Nutrient Task Force. The results of 1 of 6 topical reports (Goolsby and others, 2000, Task Force Science Assessment Topical Report 3) includes historical data on streamflow and concentrations of dissolved nitrogen (N), phosphorous (P), and silica (Si)(nutrients), along with estimates of monthly, and annual (calendar year) flux and yield of nutrients. Information from this report is provided here for: 9 major sub-basins of the Mississippi River and 36 smaller sub-basins. Information on 6 additional smaller sub-basins for which daily streamflow data was not available are not provided here. Flux and yield estimates are provided for a baseline period of 1980-96. However, estimates are provided from the beginning of the period of record (before 1980). Water quality monitoring is no longer conducted and current flux estimates are no longer provided for many of these stations.
Spread sheets with flux and basin yield estimates for nitrate, total nitrogen, orthophosphorus, total phosphorus, silica, and chloride:
Total flux and yield estimates for the Mississippi River include the diversion into the Atchafalaya River at the Old River Outflow and are listed under "Mississippi River at St. Francisville, LA". The total flux and yield estimates from the Mississippi-Atchafalaya-Red River Basin are listed under "Total to Gulf of Mexico."