The flux of a river-borne constituent such as nitrate is the amount that passes a given point on the river over a given period of time.

Nutrient flux = streamflow (discharge) TIMES nutrient concentration in streamwater.

• nutrient flux and yield estimates for 4 sites on the Mississippi River or its major tributaries and to the Gulf of Mexico for the period extending from the mid-1970’s to the present (2004) for most sites. The models used to calculated nutrient flux are an improvement pervious methods.

• nutrient flux and yield estimates for 9 stations on the Mississippi River and its major tributaries and 36 sites on smaller rivers for the period extending from the mid-1970’s to the mid-1990’s for most sites. These estimates are those that were calculated as described in the Task Force Science Assessment Topical Report 3.