Environmental Review Toolkit
Water, Wetlands, and Wildlife


Mr. Fred Bank
Federal Highway Administration
400 7th Street, SW
Washington, DC 20590
(202)366-5004 (ph)
(202)366-3409 (fax)
Dr. Kenneth D. Kerri
California State University, Sacramento
6000 J Street
Sacramento, CA 95819
(916)456-6142 (ph)
(916)278-5959 (fax)
Dr. G. Kenneth Young, PE
GKY & Associates, Inc.
5411-E Backlick Road
Springfield, VA 22151
(703)642-5080 (ph)
(703)642-5367 (fax)
Mr. Stuart Stein, PE
GKY & Associates, Inc.
5411-E Backlick Road
Springfield, VA 22151
(703)642-5080 (ph)
(703)642-5367 (fax)


The objective of an ongoing study is to gather and to synthesize the results of past research on highway stormwater runoff into a single-volume user's manual on water quality impact assessment and mitigation. The manual will be immediately useful to highway designers and environmental professionals by presenting the available and appropriate impact prediction and mitigation tools for use during highway project planning and development activities. This paper represents a status report on the first phases of the study: literature search and interviews.

The project has three components: a literature search on existing research results and operational findings on highway stormwater runoff that identifies existing water quality impact assessment and mitigation techniques; interviews with highway practitioners concerning the use of research results including maintenance of mitigation measures; and development of the single-volume, practical guidance manual.

This paper focuses on the first and second component, iterative search and interviews with highway practitioners. A detailed questionnaire was developed and sent to nine highway departments in different areas of the country (each of the FHWA regional offices). A major finding of this survey is that many of the departments recognize and follow the often restrictive water quality regulations associated with NPDES Stormwater and Clean Water Act Sections 404 and 401. However, hard supporting data on highway runoff water quality impacts are generally not available and studies are based on extrapolative science and hypothecation.


Prior EPA and FHWA research was performed during the early to mid 1970's on highway runoff and its water quality impacts to receiving waters. The Midwest Research Institute, MRI, compiled an EPA manual in 1973 to predict runoff water quality which served as a planning tool until additional measurements and research occurred. Much of this subsequent research was performed in a multi-phased approach, by various consulting organizations. About the time of the MRI report, in 1972, the need to gather information on highway runoff was established in the report "Character and Significance of Highway Runoff Waters, A Preliminary Appraisal." The report included recommendations for mitigating runoff effects and for conducting an intensive study of highway runoff water quality and its significance. The following summarizes the multi-volume research reports concerning highway impacts on water quality developed by the FHWA beginning in the mid 1970's.

  1. "Constituents of Highway Runoff" - This six-volume report, completed in 1981, developed a predictive procedure for determining the pollutant characteristics of stormwater draining from roadway surfaces. The procedure is composed of equations which predict runoff volumes and pollutant wash-off coefficients for 17 water quality parameters for 3 types of highways.

  2. "Sources and Migration of Highway Runoff Pollutants" - This four-volume report, completed in 1984, identifies the sources of potential water pollutants, their deposition and accumulation within the highway facility and their subsequent removal to the surrounding environment. The purpose of this research was to develop methods for controlling pollutant sources and mitigation measures to lessen pollutant levels entering receiving waters.

  3. "Effect of Highway Runoff on Receiving Waters" - Completed in 1985, this five-volume report analyzes the effects of highway stormwater runoff on receiving waters. Included in the effort were one-year field studies at three sites and preparation of three user-oriented manuals which provide guidelines for collecting information for use in highway project environmental assessments.

  4. "Highway Maintenance Impacts to Water Quality" - This four-volume series of reports, completed in 1985, summarizes a research project involving impacts from highway maintenance practices on water quality. Research efforts included 1) evaluating the impact potential of routine practices, 2) developing assessment methods for specific practices, 3) identification of measures to mitigate impacts and 4) conducting field studies to better define impacts from two common practices, herbicide application and surface treatment (seal-coating).

  5. "Retention, Detention, and Overland Flow for Pollutant Removal from Highway Stormwater Runoff" - This report, completed in 1987, provides interim guidelines for the removal of pollutants from highway stormwater runoff. Three general types of management measures have been determined, through previous FHWA studies, to be effective in treating highway runoff: vegetative controls (overland flow and grassed channels), detention basins (wet detention basins and wetlands), and retention measures (retention basins, trenches and wells). These interim design guidelines have been developed based on experience of the project team and by a thorough review of available literature.

  6. "Pollutant Loadings and Impacts from Highway Stormwater Runoff" - Published in 1990, this is a culminating analytical effort using the results of previous water quality studies in concert with hydraulic, environmental, and related concerns. The results of this study include a probabilistic design procedure for estimating impacts to waters receiving highway stormwater runoff. The procedure utilizes and expands upon the predictive model developed in the first series of reports. Additional runoff water quality data collected by this and other studies subsequent to the original work in the first phase were used to refine the regression analyses supporting the predictive procedure. Procedures are also included for evaluating the likelihood of the predicted pollutant discharges causing water quality problems. The design procedure is available in both manual and personal computer formats.

The information gathered in this research effort is scattered through numerous multi-volume reports, a variety of computer software, and other sources. These scattered sources have been useful in providing techniques and guidelines which can be used to address highway impacts on water quality. Because of the fragmentation of the research results, it has become necessary to centralize (focus) the results into a single report which can be effectively utilized by the FHWA, State Highway Administrations (SHAs), and other highway professionals. In fact, organization and centralization of such information was identified as the number one priority for FHWA/TRB research efforts on water quality by a broad-based committee of Federal employees, State DOT employees, and highway practitioners. A problem with the computerized design procedure is indiscriminate usage of the computer program without checking the written procedures which contain caveats, particularly the need to check results with site-specific data.

Also, in the period of time since the research was performed, highway maintenance activities, and automobile technology has changed, resulting in a revived interest in transportation impacts on water quality. There currently is greater awareness of the impacts of trace amounts of contaminants and their changing nature. Changes such as the disappearance of leaded fuel, the evolution of construction materials (e.g., rubber tires are being pulverized and added into pavement mixtures), and an increase in environmental awareness have stimulated the need to revisit earlier studies. In addition, EPA's shifting emphasis on diffuse (nonpoint) pollution sources has begun to focus on the highways and transportation system under the National Pollutant Discharge Elimination System (NPDES) and the Coastal Zone Act Reauthorization Amendment (CZARA). This study responds to the need to develop a unified user's manual which condenses prior research results, while still being sensitive to technological and administrative changes which have shaped the need for this research.


The interview objective is to contact selected researchers and highway practitioners to collect available results of research, development and current practice activities. The main reasons for the interviews are to insure that relevant information sources are included and to gage the institutional and operational requirements that the manual will address.

The first step in the interview process was to develop a detailed questionnaire to mail to the practitioners. A five page form was developed which encompassed 25 fundamental questions. The questions were organized into the following major categories:

  • Coordination with environmental agencies and the public.

  • Available data and materials.

  • Evaluation methods.

  • General information.


Questionnaires were sent to nine highway departments in different states, and all responses were received within two months. In addition to the completed questionnaires, many of the practitioners also sent copies of state funded research reports. The following summarizes the responses to questions in the four general categories.

Coordination with Environmental Agencies and the Public

  • Each state has an environmental agency with water quality oversight (e.g., Department of Environmental Quality, Water Resources Control Board, etc.) In addition, State Fish and Wildlife agencies have jurisdiction over water quality issues relating to the biological community, and State Health Departments oversee drinking water issues.

  • The most restrictive water quality regulations for highway practitioners to follow include NPDES stormwater and Clean Water Act sections 404 and 401. Total maximum daily load (TMDL) requirements are starting to catch on and have the potential to be very restrictive on highway projects.

  • Public involvement is typically handled through public hearings and meetings on Environmental Assessments and Environmental Impact Statements, as well as any other mandates of the National Environmental Policy Act (NEPA). The public is always given opportunity to review and comment on environmental documents.

Available Data and Materials

  • Most of the practitioners cited previous FHWA research (see Background Section) as a source of information on pollutant loads generated by highway activities. Also cited is EPA's Guidance Specifying Management Measures for Sources of Nonpoint Pollution in Coastal Waters."

  • Practitioners also cited the FHWA research as a source of information on Best Management Practice (BMP) effectiveness and design guidance. Other cited references include: "Controlling Urban Runoff: A Practical Manual for Planning and Designing Urban BMPs", prepared by the Metropolitan Washington Council of Governments; various research reports authored by Yousef for the Florida Department of Transportation(11,12); and various State Highway Administration BMP manuals such as those prepared for California (13) and the Puget Sound areas.(14)

  • Most practitioners did not know of (or at least did not list any) computer models which could contribute to this manual. A couple listed EPA's Stormwater Management Model (SWMM) and the software companion to FHWA's "Pollutant Loadings and Impacts from Stormwater Runoff."(8)

  • Most practitioners did not know of monitoring programs which could contribute to this manual, although many recognize that monitoring will be conducted as part of the their State Highway Administration NPDES compliance program. Monitoring data are scarce and its expense probably will work to make additional data sparse.

Evaluation Methods

  • Most States do not require that highway operations and maintenance runoff impacts be assessed. Where assessment is required, FHWA's model (8) is used as are other models, including regression equations.

  • More detail may be required for analysis of high average daily traffic (ADT) projects and/or projects which may impact sensitive habitat.

General Information

  • Salt programs and construction are the highway operations and maintenance activities which are of greatest concern for water quality impacts.

  • Practitioners see the need for this manual to include current research on BMP effectiveness, design guidance, and cost.


While runoff water quality has become a major environmental issue with the passage and implementation of the NPDES stormwater program, quantification of nonpoint source pollution loads and resulting water quality impacts are not typical activities within highway planning and design procedures. Actual data are scarce. The surveys indicate that the selected practitioners are well aware of current environmental regulations, but are not necessarily familiar with research funded at the state and local levels. This manual will assist practitioners through the identification and summarization of numerous important research efforts into a unified user's manual on water quality impact assessment and mitigation.


  1. Environmental Protection Agency, Office of Air and Water Programs, Methods for Identifying and Evaluating the Nature and Extent of Nonpoint Sources of Pollutants, EPA-430/9-73-014, Washington, DC, October 1973.

  2. R.O. Sylvester, Character and Significance of Highway Runoff Waters, Report No. 7.1, Washington State Highway Commission, December 1972.

  3. M.K. Gupta, Constituents of Highway Runoff, Vol. I - VI, FHWA/RD-81/042-047, Envirex, Inc., Federal Highway Administration, Washington, DC, February 1981.

  4. N.P. Kobriger, Sources and Migration of Highway Runoff Pollutants, Vol I - IV, FHWA/RD-84/057-60, Federal Highway Administration, Washington, DC, May 1984.

  5. T.V. Dupuis, Effects of Highway Runoff on Receiving Waters, Vol. I - VI, FHWA/RD-84/062-66, Rexnord, Inc., Federal Highway Administration, Washington, DC, June 1985.

  6. A.D. Kramme, Highway Maintenance Impacts to Water Quality, Vol. I - IV, FHWA/RD/057-60, Federal Highway Administration, Washington, DC, March 1985.

  7. M.E. Dorman, J. Hartigan, F. Johnson, and B. Maestri, Detention, Retention and Overland Flow for Pollutant Removal from Highway Stormwater Runoff, Versar, Inc., FHWA/RD-87/056, Federal Highway Administration, Washington, DC, June 1987.

  8. E.D. Driscoll, Pollutant Loadings and Impacts from Highway Stormwater Runoff, Vol. I - VI, FHWA/RD-88-006-9, Woodward-Clyde Consultants, Federal Highway Administration, Washington, DC, April 1990.

  9. Environmental Protection Agency, Office of Water, Guidance Specifying Management Measures for Sources of Nonpoint Pollution in Coastal Waters, 840-B-92-002, Washington, DC, January 1993.

  10. T.R. Schueler, Controlling Urban Runoff: A Practical Manual for Planning and Designing Urban Best Management Practices, Metropolitan Washington Council of Governments, 1987.

  11. Y.A. Yousef, Best Management Practices-Effectiveness of Retention/Detention Ponds for Control of Contaminants in Highway Runoff, University of Central Florida, Florida State Department of Transportation, Gainesville, FL, August 1986.

  12. Y.A. Yousef, Best Management Practices: Removal of Highway Contaminants by Roadside Swales, University of Central Florida, Florida State Department of Transportation, Gainesville, FL, July 1985.

  13. Camp Dresser & McKee, Inc., Larry Walker Associates, California Stormwater Best Management Practice Handbook - Municipal, prepared for the Stormwater Quality Task Force, California State Water Resources Control Board, Sacramento, California, 1993.

  14. Washington State Department of Ecology, Stormwater Management Manual for the Puget Sound Basin (The Technical Manual), Publication #91-75, February 1992.

Questions and feedback should be directed to Susan Jones (Susan.Jones@dot.gov, 202-493-2139) and Marcel Tchaou (Marcel.Tchaou@dot.gov, 202-366-4196)

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