Evaluation of changes in landscape loading of total nitrogen to U.S. waters using monitoring results from the National Aquatic Resource Surveys

Uncertainty about how land use practices changes will quantitatively affect water quality and how long it will take to see improvements from management actions hinder efforts to reduce nitrogen (N) in streams. It is important to couple data about changes in inputs to understand changes in water quality over time. We used two existing USEPA datasets to understand the changes in stream water quality over time and how land management can affect stream total N concentration (TN) in the contiguous US:
◆ USEPA’s national inventories of N inputs (2002-2012, fine-scaled) for the contiguous US

◆ Stream TN concentration from the EPA National Rivers and Streams Assessment (NRSA, yrs. 2000-2004, 2008-2009, and 2013-2014). All samples were collected during summer.