skip to main content
Environmental Review Toolkit


Wetlands, coastlines, and water quality are vital parts of the natural ecosystem and require careful planning to avoid, minimize, and compensate unavoidable impacts as a result of transportation projects. FHWA provides information and guidance to Federal, State, and local agencies to assess the function of these resources and restore the integrity of the Nation’s aquatic ecosystems.

For information related to specific Legislation, Regulation, and Guidance related to water resources, please visit the Natural Environment Legislation page.

Wetlands and Watersheds

plus sign Watersheds
minus sign Watersheds

A watershed is the boundary of a drainage basin that has an area defined by a common drainage endpoint, the terms watershed and drainage basin commonly are uses synonymously. Natural and anthropogenic land covers within each watershed can affect the receiving water quality and ecology directly and indirectly. Transportation and other developed land covers can generate or convey stormwater.

The United States Environmental Protection Agency (EPA) provides resources on protecting watersheds and other water sources, including the How’s My Waterway tool that provides lists of organizations working to protect local watersheds nationwide.

The U.S. Geological Survey provides the StreamStats tool that can be used for watershed delineation, querying basin properties, and calculating streamflow statistics in many states.

The U.S. Geological Survey investigates the occurrence, quantity, quality, distribution, and movement of surface and underground waters and disseminates the data to the public on the National Water Information Website.

Granato, G.E., 2012, Estimating basin lagtime and hydrograph-timing indexes used to characterize stormflows for runoff-quality analysis: U.S. Geological Survey Scientific Investigations Report 2012–5110, 47 p.

plus sign Wetlands and Aquatic Resources
minus sign Wetlands and Aquatic Resources

Wetlands are delicate natural resources that serve many functions. Not only do they provide habitat for aquatic species, but they also improve water quality and manage floodwaters.

The Federal Government offers the following resources for minimizing and mitigating the impacts from transportation projects on wetlands:

5 Star Wetland and Urban Waters Restoration Grants - This program brings together students, conservation corps, other youth groups, citizen groups, corporations, landowners and government agencies to provide environmental education and training through projects that restore wetlands and streams. The program provides challenge grants, technical support and opportunities for information exchange to enable community-based restoration projects. Funding levels are modest, from $10,000 to $40,000, with $20,000 as the average amount awarded per project.

Results of the FHWA Domestic Scan of Successful Wetland Mitigation Programs, 2005 - Managing and mitigating wetlands impacts due to highway projects is a significant issue for FHWA and State DOTs. To help find out what kind of issues were most problematic, and to identify successful solutions that were being used, the Office of Environment and Planning conducted an interagency scan of wetland mitigation and impact management practices in eight States. There was a strong focus on mitigation banking, including what issues and solutions have been associated with the development of successful, workable wetland mitigation banks. Where banks were not being used, successful on-site mitigation projects were examined.

Stochastic Empirical Loading and Dilution Model (SELDM) software archive, 2023 - Together with partner organizations, the USGS is involved in data collection, analysis, and synthesis to improve our understanding of wetlands.

Executive Orders

Subject/Title Resource URL E.O. Number
Executive Order 12962 on Recreational Fisheries Executive Order 12962
Amendments to Executive Order 12962 Executive Order 12962
Executive Order 11988 on Floodplain Management Executive Order 11988
Executive Order 11990 on Protection of Wetlands Executive Order 11990


FHWA offers the following instructional recording on wetlands:

RIBITS Wetland Mitigation Tool - Live Demonstration
FHWA and the U.S. Army Corps of Engineers (USACE) have produced an instructional recording for transportation users on how to use the Army Corps Regulatory In lieu fee and Bank Information Tracking System (RIBITS) to find mitigation credits for transportation projects. A version of this training was presented as a webinar in December of 2013. RIBITS is a web site that provides information on stream and wetland mitigation banks and in-lieu fee programs across the country. Users can access a wide range of information on wetland mitigation and endangered species conservation banks including the availability of mitigation credits, bank ledgers, service areas, and national and local policies and practices for the use of mitigation and conservation banks. Viewers of this demonstration will learn about:

  • Using RIBITS (Regulatory In lieu fee and Bank Information Tracking System) to determine if you can purchase mitigation credits for your transportation project.
  • Documentation for these mitigation banking or in-lieu fee programs.
  • New RIBITS features for transportation professionals.

Access the recording.

Stormwater Management and Water Quality

When precipitation occurs over highways and other impervious surfaces, the resulting stormwater can carry debris, sediment, and chemicals into water sources, diminishing their quality. In addition to the stormwater runoff that carries sediment and pollutants into water sources, highway construction and maintenance activities have potential to affect nearby bodies of water.

The FHWA provides the following reports and guidance for controlling stormwater runoff along highways and minimizing the effects of transportation projects on water quality:

plus sign Research and Reports
minus sign Research and Reports

Federal Highway Administration Reports


Note: The older "Driscoll Model" has been superseded by the Stochastic Empirical Loading and Dilution Model (SELDM).

  • Driscoll, E.D., Shelley, P.E., and Strecker, E.W., 1990a, Pollutant loadings and impacts from highway stormwater runoff, v. I-Design procedure: Washington, D.C., Federal Highway Administration Final Report FHWA-RD-88-006, 67 p.
  • Driscoll, E.D., Shelley, P.E., and Strecker, E.W., 1990b, Pollutant loadings and impacts from highway stormwater runoff, v. II-User’s guide for interactive computer implementation of design procedure: Washington, D.C., Federal Highway Administration Final Report FHWA-RD88-007, 23 p.

Runoff Quality Characterization

Best Management Practices

Regulatory Compliance


U.S. Geological Survey Reports

Best Management Practices

Runoff Quality Characterization

Regulatory Compliance


National Cooperative Highway Research Program Reports

Best Management Practices

Regulatory Compliance

plus sign Stormwater Model
minus sign Stormwater Model

The Federal Highway Administration developed a set of stormwater-modeling tools to transform disparate and complex scientific data into meaningful information about the risk for adverse effects of runoff on receiving waters, the potential need for mitigation measures, and the potential effectiveness of such management measures for reducing these risks. These tools include:

  • Highway-Runoff Database (HRDB)
  • Stochastic Empirical Loading and Dilution Model (SELDM)
  • Kendall-Theil Robust Line (KTRLine) analysis tool
  • InterpretSELDM a graphical post processor for interpreting SELDM outputs

These tools are documented in the following publications:

plus sign Additional Resources
minus sign Additional Resources
  • AASHTO Technical Committee on Hydrology and Hydraulics (TCHH), 2024 - TCHH members actively promote, solicit, and participate in national and state hydraulic engineering research. TCHH collaborates and coordinates with committees of the Transportation Research Board (TRB) and state DOTs to develop research need statements applicable to hydraulic engineering for funding through the National Cooperative Highway Research Program (NCHRP).
  • AASHTO Stormwater Working Group of the Committee on Environmental and Sustainability (CES), 2024 - The CES supports its members in delivering a national, regional, and local intermodal transportation system that is safe, resilient, economical, efficient, environmentally sound, and aesthetically and culturally sensitive.
  • The International Stormwater Best Management Practices (BMP) Database project website features a database of over 600 BMP studies, performance analysis results, tools for use in BMP performance studies, monitoring guidance and other study-related publications.
  • Stormwater Discharges from Transportation Sources (EPA) - Similar to traditional stormwater management authorities (cities and counties), transportation authorities are also responsible for managing the stormwater runoff that discharges to our nation’s waters via regulated municipal separate storm sewer systems (MS4s) along streets, roads, and highways.
  • TRB Publications about Environment - The Transportation Review Board maintains an updated list of publications related to transportation and the environment.
  • Evaluation of Best Management Practices for Highway Runoff Control, 2006 - This report focuses on improving the scientific and technical knowledge base for the selection of best management practices (BMPs) through a better understanding of BMP performance and application. This report documents an extensive program of research on the characterization of BMPs and stormwater, and the influence of factors such as land use practice, hydraulic characteristics, regional factors, and performance evaluation. The report includes a CD containing a spreadsheet model and three additional volumes: User’s Guide for BMP/LID Selection, Appendices to the User’s Guide, and Low Impact Development Design Manual for Highway Runoff Control.
Subject/Title Resource Agency
Erosion and Sediment Control on Highway Construction Projects (23 CFR 650B) Regulation FHWA
Erosion and Sediment Control on Highway Construction Projects (NS 23 CFR 650B) Guidance FHWA
Guidance on 23 U.S.C. §328 Environmental Restoration and Pollution Abatement Memorandum FHWA
U.S. Geological Survey Transportation-Related Water Projects Website USGS


FHWA’s regulations, policies, and guidance implement national floodplain goals and requirements while keeping public safety paramount and balancing flood risks, environmental stewardship, and cost in the planning, design, construction, and operations/maintenance of transportation infrastructure.

View Executive Order 11988 “Floodplain Management”.

View FHWA EO 11988 implementation procedures, 23 CFR 650 subpart A.

Coastal Zone Management

The Coastal Zone Management Act, administered by the National Oceanic and Atmospheric Administration (NOAA), provides for the management of the nation’s coastal resources and includes programs such as the National Coastal Zone Management Program. This program is a partnership between coastal States and territories and the Federal government. The FHWA coordinates with the State Coastal Zone Management agency or appropriate local agencies when a proposed action is within, or is likely to affect land or water uses within, the area covered by a State Coastal Zone Management Program approved by the Department of Commerce.