National Nutrient Inventory Portfolio
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The National Nutrient Inventory Portfolio is a multi-agency project that offers tools and datasets to help decision makers identify point and non-point source nitrogen and phosphorus pollution hotspots and link them to water quality conditions across the country. This portfolio supports federal, state, tribal, and local partners in their efforts to assess and improve water quality to benefit aquatic and human health.
Project Overview
The mission of the nutrient inventories project is to assist with tracking major fluxes of nutrients across agricultural, natural, and urban environments. These inventories provide users with databases to help them identify the potential types and sizes of nutrient pollution sources in their locality, and how these nutrient pollution sources are influencing local and downstream water quality conditions.
Goals
- Develop nationwide, region-specific, and locally downscaled nutrient inventories based on client/partner feedback and guidance.
- Determine metrics that best approximate point and non-point source pollution and are effective components of watershed restoration plans.
- Relate shifts in nutrient sources to observed water quality conditions to highlight success stories and ongoing/emerging challenges in reducing nitrogen and phosphorus pollution to waterways.
Outcomes
- Inventories are used to track how nutrient pollution sources are evolving across the landscape and explain nutrient concentrations in surface and ground water through models. These models can be used to predict aquatic ecosystem condition in other unmonitored areas.
- Inventories can be incorporated into existing models and restoration planning schemes to provide current data on nutrient input and management conditions.
- The National Nutrient Inventory Explorer (NNIE) tool, an online visualization and data download platform, is anticipated to be released in the spring of 2026.
Contact Us about National Nutrient Inventories
Robert Sabo
EPA Project Lead
sabo.robert@epa.gov
202-564-8421
Jana Compton
compton.jana@epa.gov
541-754-4620
Publications
Journal Articles
Development of the Nutrient Inventory
- Major Point and Nonpoint Sources of Nutrient Pollution to Surface Water Have Declined Throughout the Chesapeake Bay Watershed (2022)
- Considerations When Using Nutrient Inventories to Prioritize Water Quality Improvement Efforts Across the US (2021)
- Phosphorus Inventory for the Conterminous United States (2002–2012) (2021)
- Decadal Shift in Nitrogen Inputs and Fluxes Across the Contiguous United States: 2002–2012 (2019)
- Reactive Nitrogen Inputs to US Lands and Waterways: How Certain are we About Sources and Fluxes? (2013)
- Intentional Versus Unintentional Nitrogen Use in the United States: Trends, Efficiency and Implications (2013)
Application of the Nutrient Inventory to Water Quality or Other Endpoints
- Our National Nutrient Reduction Needs: Applying a Conservation Prioritization Framework to US Agricultural Lands (2024)
- Effects of point and nonpoint source controls on total phosphorus load trends across the Chesapeake Bay watershed, USA (2023)
- Nutrient explorer: An analytical framework to visualize and investigate drivers of surface water quality (2023)
- The changing nitrogen landscape of US streams: Declining deposition and increasing organic nitrogen (2023)
- Comparing Drivers of Spatial Variability in US lake and Stream Phosphorus Concentrations (2023)
- Shifts in the Composition of Nitrogen Deposition in the Conterminous United States are Discernable in Stream Chemistry (2023)
- An Index of Nitrogen Sources and Processing Within Watersheds for National Aquatic Monitoring Programs (2022)
- Regional Patterns and Drivers of Total Nitrogen Trends in the Chesapeake Bay Watershed: Insights from Machine Learning Approaches and Management Implications (2022)
- Context is Everything: Interacting Inputs and Landscape Characteristics Control Stream Nitrogen (2021)
- Long‐Term Mississippi River Trends Expose Shifts in the River Load Response to Watershed Nutrient Balances Between 1975 and 2017 (2021)
- Patterns and Predictions of Drinking Water Nitrate Violations Across the Conterminous United States (2020)
- Nitrogen Inputs Drive Nitrogen Concentrations in US Streams and Rivers During Summer Low Flow Conditions (2018)
- Cost Of Reactive Nitrogen Release from Human Activities to the Environment in the United States (2015)