Gulf of Mexico Data Atlas Gulf of Mexico Data Atlas

Water Quality

Nutrients - Estuarine

The health of the Gulf largely depends on the quality of water discharged from upstream watersheds into the estuaries around the gulf. Much of the excess nutrients from urban and agricultural runoff discharges into bays, estuaries, and sounds, and eventually ends up in the Gulf of Mexico. These nutrients contribute to problems such as hypoxia and red tides Statistical methods are often used to explain in-stream measurements of water quality (such as nutrients) in relation to upstream sources and watershed properties (soil characteristics, rainfall, and land use) that influence the transport of nutrients to streams and their delivery to receiving water bodies such as estuaries. U.S. Geological Survey scientists developed a statistical model that integrates monitoring data with landscape information. This model, known as SPARROW (SPAtially-Referenced Regression On Watershed attributes), is watershed-based and designed for use in predicting long-term average values of water characteristics, such as concentrations of nutrients and other selected constituents that are delivered to downstream receiving waters. This map shows the estimated delivered yields and delivered loads of nitrogen and phosphorus as estimated by SPARROW for the water body areas as defined by the NOAA Coastal Assessment Framework (CAF) for the estuaries, bays, and sounds along the U.S. Gulf of Mexico coast in 2002 are available. Delivered yield is the estimated amount of nutrients delivered to an estuary divided by the area of the upstream drainage area that drains to the estuary. Delivered load is the amount of nutrients estimated to be delivered from the upstream drainage basin to each of the estuaries draining into the Gulf of Mexico.

Additional image formats and visualization tools:

Nutrients - Estuarine Atlas Dataset