New USGS Water Quality Findings: Major Sources and Losses of Nutrients in the Missouri River Basin Portion of the U.S.
Major Sources and Losses of Nutrients in the Missouri River Basin Portion of the United States--
New SPAtially Referenced Regression On Watershed attributes (SPARROW) models were developed for the Missouri River basin to estimate nutrient loads in streams (including unmonitored streams) and identify sources of those loads. Agricultural sources (fertilizer and manure) were found to be the largest nutrient sources throughout a large part of the basin, contributing approximately 62% of the load to streams on average. For phosphorus, sediment mobilized from stream channels was an important source for medium and larger streams, contributing approximately 23% of the total load to streams on average. Loss due to denitrification enhanced by agricultural irrigation was found to be a significant sink for nitrogen, and was estimated to reduce the load reaching the Mississippi by as much as 17%. Losses due to sedimentation, algal uptake, and denitrification in reservoirs and lakes were found to be important sinks for nitrogen and phosphorus, reducing the load to the Mississippi River by approximately 16% and 33%, respectively.
The modeling results are available through a new Decision Support System that allows the user to display maps of the model predictions, relate upstream sources to downstream loads and test potential management scenarios (http://water.usgs.gov/nawqa/sparrow/dss/#region=MRB4).
For additional information on the regional model and the decision support system, contact:
Juliane Brown,
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,303-236-6876
Lori Sprague,
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, 303-236-6921
Jill Frankforter,
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, 406-457-5917
