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National Water-Quality Assessment (NAWQA) Project


1 Reported share for the Great Lakes is from confined livestock waste only; reported share for California estuaries is from unconfined livestock waste only (see Ruddy and others, 2006, for definitions).

2 Reported share for the Great Lakes and the Gulf of Mexico estuaries also includes nitrogen fixation by agricultural crops; reported share for California estuaries also includes waste from confined livestock.

3 Share is not estimated for the Great Lakes; reported share for the Pacific Northwest estuaries also includes estimated share from septic waste.

4 Forested-land share is reported separately only for Pacific Northwest and California estuaries; for other regions the share is assumed to be included in the atmospheric deposition term. 

5 Reported for the Pacific Northwest estuaries only, consists primarily of load delivered from Canada with a small amount from springs and return flows from power plants within the United States.

Tracking the Source and Quantity of Nutrients to the Nation's Estuaries


Access maps of watershed nutrient contributions to the Nation’s Estuaries.

Estuary Map Pacific Northwest Coast Gulf of Mexico California Coast Great Lakes Atlantic Coast Northeast Atlantic Coast Southeast Description


Regional Nutrient SPARROW Model Assessments

SPARROW Models--Nutrients, Organic Carbon, Salinity, and Sediment

SPARROW Model Fact Sheet

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Page Last Modified: Tuesday, 05-Mar-2019 12:33:05 EST