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Total Mississippi River Basin Nutrient Flux to the Gulf of Mexico (through 2005)

The following estimates of delivery of flow and nutrient flux to the Gulf of Mexico were provided as a periodic (5-year) update to nutrient fluxes to evaluate trends in response to natural and human-induced changes. These estimates employed an improved methodology over previous estimates. Therefore updates were provided for the entire period of record and superseded previous estimates. The estimates were made on a annual basis from July to June. Explanation of methods used for this analysis.

Monthly and annual nutrient flux estimates through 2005

• Total Mississippi and Atchafalya River to the Gulf of Mexico, 1979 through 2005:
• Gulf Monthly Flux-Yield.xls
• Gulf Annual (July-June) Flux-Yield.xls
  
  
• Lower Mississippi River at St Francisville, LA, 1968 through 2005:
• Lower Miss Monthly Flux.xls
• Lower Miss Annual (July-June) Flux.xls
  
  
• Atchafalaya River at Melville, LA, 1979 through 2005:
• Atchafalaya Monthly Flux.xls
• Atchafalaya Annual (July-June) Flux.xls

All flux estimates are in metric tons per unit time as N, P, or SiO2 and all yield estimates are in kilograms per square kilometer per unit time. Discharge estimates are given in cubic feet per second.

The nutrient flux and yield estimates are updated every year in early July so that nutrient flux estimates for the previous 12 months (July through June) can be provided in a timely manner and coordinated with surveys of the Gulf of Mexico hypoxic zone, which occur in mid-July.