Nutrients Research
- Nutrient Sources and Fate
- Nutrient Impacts and Tools to Support Criteria Development
- Nutrient Reduction Approaches
- Implementation of Nutrient Reduction Strategies
- Additional Resources
— primarily excess nitrogen and phosphorus — is the most widespread water quality problem facing the United States, with far-ranging consequences for the environment, economic prosperity, and human health and well-being. Excess nutrient loadings to surface and groundwater can contribute to harmful algal blooms (HABs), hypoxia, fish kills, biodiversity changes, and degradation of drinking water sources, increasing treatment costs. Despite progress to reduce nutrient loadings, these pollutants continue to be discharged at concentrations that cause adverse impacts to human health and aquatic and terrestrial ecosystems. EPA research examines the appropriate spatial and temporal context for nutrient reductions and conservation practices for tracking interventions to meet nutrient reduction goals in a comprehensive manner.
Nutrient Sources and Fate
Changes in climate patterns, increases in extreme weather events, and variations in nutrient sources, including excess nutrients stored in soils, sediments, and groundwater, affect watershed-scale nutrient fate and transport. Fate is where a nutrient eventually ends up, and transport is how it gets there. It is important for researchers to understand the types and locations of nutrient sources in waterbodies. and where the most active sites of nutrient sink, transformation, and transport process. Advancing this science will help researchers characterize how effectively surface waters will respond to restoration and recovery efforts.
EPA researchers are examining nutrient source inputs to the landscape and aquatic systems across a wide variety of spatial and temporal scales, from small watersheds to large river basins.
Research Focus
- Finding and assessing new applications of the nitrogen and phosphorus nutrient inventories.
- Analyzing the locations and timing of legacy nutrients via watershed and waterbody source, sink, and transport models.
- Determining new methods to identify sources, sinks, and fate of nutrients.
Related Resources
- Nitrogen Modeling and Mapping
- National Nutrient Inventory Portfolio
- Advanced Nutrient Modeling
- Water Research Webinar: Effectiveness of Nutrient Management for Reducing Nutrient Losses from Agricultural Fields (February 28, 2024)
- Harmful Algal Blooms, Hypoxia, and Nutrients Research Webinar Series: Using Wetlands to Reduce Nutrient Loadings to Rivers and the Coast (May 24, 2024)
Nutrient Impacts and Tools to Support Criteria Development
Research on how excess nutrients impact water quality and ecological conditions is needed to develop protective water quality thresholds and new approaches to improve nutrient status assessments and identify impairments.
EPA researchers are working with states, National Estuary Program sites, and other EPA offices to co-produce this information. These partnerships aim to develop, apply, and communicate new and existing methods to effectively address the issue of nutrient pollution from local watersheds to national scales.
Research Focus
- Assessing the impacts of nutrients and different stressors on estuaries and coastal waters.
- Assessing nutrient impacts on aquatic life in freshwater systems.
- Modeling nutrient-related stressors and ecosystem recovery in freshwater and coastal systems.
Related Resources
- Water Quality Impacts of Nutrients
- Human Dimensions of Water Quality
- National Aquatic Resource Surveys
Nutrient Reduction Approaches
There is a need to better understand how management practices affect nutrient fate and transport and the interacting water quality and ecological dynamics from diffuse sources (i.e., nonpoint sources Diffuse pollution sources (i.e., without a single point of origin or not introduced into a receiving stream from a specific outlet). The pollutants are generally carried off the land by stormwater. Common nonpoint sources include runoff from agriculture, forestry, urban environments, land disposal, and saltwater intrusion. [EPA 841-B-04-001] [Terms of Env]) including from agriculture, urban, and forested landscapes. For example, there has been significant investment to implement agricultural conservation practices (ACPs) (e.g., cover crops, tillage and residue management, buffers, and natural and constructed wetlands) to reduce nutrient and sediment losses from agricultural fields. It is particularly important to understand the processes governing their effects and how cost effective these expenditures have been for reducing nitrogen and phosphorus. This includes developing strategies to increase cost effectiveness of management practices by understanding the important engineering design aspects as well as how multiple installations over time and space influence nutrient loads to waterbodies.
EPA researchers are analyzing current ACPs and other nutrient management methods to develop new approaches to improve nutrient reduction.
Research Focus
- Reviewing and synthesizing the effectiveness of nutrient management practices.
- Optimizing monitoring, modeling, and data analytics approaches for tracking program effectiveness.
- Evaluating trading and market-based approaches to improve adoption and implementation of nutrient reduction.
- Reducing nutrient losses and greenhouse gases from row crops through improved fertilizer technology and adoption.
Related Resources
- Nutrient Management
- What EPA is Doing to Reduce Nutrient Pollution
- Effectiveness of nutrient management on water quality improvement: A synthesis on nitrate-nitrogen loss from subsurface drainage
- Agriculture Nutrient Management and Fertilizer
Implementation of Nutrient Reduction Strategies
Nonpoint source nutrient pollution can come from multiple, diffuse sources. For example, as water moves over the land and through soils and groundwater, it picks up and carries away natural and human-made pollutants, eventually depositing them into water bodies. Because of the multiple inputs — whose sources may span different jurisdictional boundaries — effective nutrient reduction strategies require partnerships with federal, state, Tribal, and local community entities to leverage expertise and limited resources.
EPA researchers are studying and documenting innovations in nutrient reductions from these partnerships and indigenous knowledges. Researchers are also developing and enhancing tools to assist in identifying priority areas to optimize measurable nutrient reduction outcomes at watershed or larger scales.
Research Focus
- Designing and implementing a nutrient reduction program.
- Implementing and evaluating, or modeling scenarios of, solutions-driven research to reduce nonpoint nutrient pollution at scales necessary to achieve water quality goals.
- Co-producing research with communities nationwide who are experiencing various sources and impacts from nutrient pollution.
Related Resources
- Water Research Webinar: Reducing Nitrogen in Groundwater Through Enhanced Onsite Wastewater Treatment and Wetland Restoration (June 28, 2023)
- Water Research Webinar: VELMA Watershed Modeling in the Puget Sound (April 26, 2023)
- Water Research Webinar: Integrated Approaches in Community Nonpoint Source Nutrient Management (August 24, 2022)
Additional Resources
Models and Tools
- Cyanobacteria Assessment Network Mobile Application (CyAN App)
- Water Quality Analysis Simulation Program (WASP)
- Causal Analysis/Diagnosis Decision Information System (CADDIS)
- Global Change Explorer
- WATER, Soil, and Hydro-Environmental Decision Support System (WATERSHEDSS)