Low-Impact Development Practices to Mitigate the Impacts of Nutrients and Pathogen Contributions from Highway Rights-of-Way

Focus Area

Water Quality/Wetlands


Natural Resources







Research Idea Scope

Need for the Research

Stormwater runoff from transportation Rights-of-Way (ROW) may contain nutrients (particularly phosphorus and nitrogen) and may contain pathogens (though it is unclear if DOTs are a source that would “contribute” to a receiving water violation for sanitary quality), which can have adverse environmental impacts on receiving waterbodies. Accordingly, DOTs are being named or have been named in Total Maximum Daily Loads (TMDLs) for nutrients and pathogens across the country. There is a need to determine if roadways and roadside areas are a significant source of pollution as a result of discharging these constituents/indicators. There is a need to identify what Best Management Practices (BMPs) are effective and appropriate at treating these pollutants. There is also a movement to require the use of Low-Impact Development (LID) practices to treat stormwater runoff. This research would identify which LID practices are effective and appropriate at treating nutrients and pathogens within the transportation ROW setting. Research would also determine if LID is not appropriate (on a cost-benefit basis) and recommend other approaches (such as source control) that should be pursued if appropriate.

Scope of Research

The scope of this research is to determine which LID practices are appropriate from a cost and effectiveness standpoint to remove nutrients and pathogens that originate on highways and roadside areas, including an assessment as to which practices are appropriate within narrow ROW.

An important aspect of the research is to evaluate the significance of the contributions of these pollutants from road surfaces and roadside areas relative to other land uses and to provide a cost/benefit analysis (i.e., analysis of the cost to implement LID practices vs. the environmental benefit). The research will determine if the discharge of these constituents/indicators is significant and if treatment BMPs are necessary to meet the MEP standard.

This research would involve a synthesis of: 1) prior studies done to characterize the stormwater runoff from the ROW (with special focus on nutrients and pathogens) and 2) prior studies that have findings about the effectiveness of LID practices to treat nutrients and pathogens. The research would result in a) a determination of whether DOTs need to remove nutrients and pathogens from runoff to meet the MEP standard, b) if it is appropriate to include DOTs as a stakeholder in TMDLs for these constituents/indicators, and c) a list of LID practices that are appropriate for use within a transportation ROW, as well as a list of LID practices that are inappropriate for such use. Recommendations would be made as to the most effective and least costly options for DOTs to control these constituents/indicators.


DOTs are facing compliance schedules for nutrient and pathogen TMDLs that require quantitative load reductions on a defined schedule. This research is needed to assist DOTs in meeting the requirements of TMDL implementation plans, while at the same time implementing the new LID requirements. Research is also needed to inform the regulatory community if discharge from the ROW is a significant source of these constituents/indicators, and under what conditions it would be appropriate to require treatment BMPs.

Urgency and Payoff

DOTs are being named or have been named in TMDLs for nutrients and pathogens across the country. LID approaches to stormwater management are being required in NPDES permits. This research would benefit DOTs by a) providing research indicating whether DOTs are a significant source of pollution for these constituents/indicators and under what conditions this is true, b) demonstrating the types of LID measures that are effective in the removal of nutrients and pathogens, and c) providing DOTs with effective and quantitative tools for compliance with existing TMDLs.

Suggested By

Center for Environmental Excellence, Stormwater Community of Practice