I’ve asked Janice Kaspersen, editor of our companion publication, Stormwater, to provide a snapshot of SPARROW, USGS’s online decision support tool for modeling nutrient transport. Here’s her report:
A new tool from the US Geological Survey aims to help those dealing with excess nutrients in surface waters—specifically, helping them find regional models that describe nutrient transport. Excess nutrients like nitrogen and phosphorus can lead to algae blooms, oxygen depletion, and dead zones like the ones currently spreading in the Gulf of Mexico, the Chesapeake Bay, and elsewhere.
Several regional models have been developed using SPARROW (SPAtially Referenced Regressions On Watershed attributes). USGS says its online decision support system, available at http://water.usgs.gov/nawqa/sparrow/mrb/, will help researchers, watershed managers, and the public map predictions of long-term average water conditions, track transport of nutrients to receiving waters, and evaluate source reduction scenarios.
As the models show, different regions of the US have very different sources of nutrients: primarily agricultural fertilizers and animal waste in the Midwest, wastewater effluent and urban stormwater runoff in the Northeast and mid-Atlantic, and atmospheric deposition of nitrogen in some areas of the eastern US. Some large sources of phosphorus, the models show, are naturally occurring, though these too must be taken into account when planning overall source reduction or developing a TMDL.
USGS originally developed SPARROW in part to help predict water quality in unmonitored water bodies. The regional models incorporate information on land use, geology, soils, climate, location of wastewater treatment facilities, and other factors.