Environmental Review Toolkit
Water, Wetlands, and Wildlife

Storm Water Management

When precipitation occurs over highways and other impervious surfaces, the resulting stormwater can carry debris, sediment, and chemicals into water sources, diminishing their quality. The FHWA provides the following reports and guidance for controlling stormwater runoff along highways:

Stochastic Empirical Loading Dilution Model (SELDM) - The USGS, in cooperation with the FHWA, developed the Stochastic Empirical Loading and Dilution Model (SELDM) to replace the FHWA runoff-quality model developed in the 1980's and published in 1990. That model was limited to a few water-quality constituents, was based on the assumption that upstream concentrations are equal to zero, was based on water-quality standards from the 1980's, was not compatible with newer operating systems, and there was no mechanism for continuing model support. SELDM is designed as a tool that can be used 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. SELDM is designed to help develop planning-level estimates of event mean concentrations, flows and loads from a highway site and an upstream or lake basin. The model has been tested by the FHWA, many State DOTs, the EPA, and several other regulatory agencies. This resulted in a robust model that will be acceptable to DOTs, regulators, and resource-management agencies.

SELDM QR code Scan this QR code for more information about SELDM.

Driscoll Model - This model is used in the characterization of stormwater runoff pollutant loads from highways, and the prediction of water quality impacts they cause. Study results are based on monitoring data from 993 individual scam events at 31 highway runoff sites in 11 states. Impact prediction is based on a methodology previously developed and applied to urban runoff and adapted for highway runoff applications. This document provides a step-by-step procedure for computing the estimated impacts on water quality of a stream or lake that receives highway runoff. Guidance is provided for evaluating whether or not a water quality problem will result, and the degree of pollution control required to mitigate impacts to acceptable levels.

Evaluation of Best Management Practices for Highway Runoff Control - 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.

National Highway Runoff Water-Quality Data and Methodology Synthesis
Volume 1: Technical issues for monitoring highway runoff and urban stormwater, FHWA-EP-03-054
Volume 2: Project Documentation, FHWA-EP-03-055
Volume 3: Availability and documentation of published information for synthesis of regional or national highway-runoff quality data, FHWA-EP-03-056 Knowledge of the characteristics of highway runoff (concentrations and loads of constituents and the physical and chemical processes that produce this runoff) is important for decisionmakers, planners, and highway engineers to assess and mitigate possible adverse impacts of highway runoff on the Nation's receiving waters. The Federal Highway Administration and the U.S. Geological Survey began the National Highway Runoff Data and Methodology Synthesis in order to:

  • Provide a catalog of the pertinent information available
  • Define the necessary documentation to determine if data are valid (useful for intended purposes), current, and technically supportable and
  • Evaluate available sources in terms of current and foreseeable information needs

This report describes the NDAMS report-review process, summarizes results of this metadata review process, and provides an interpretation of these results. The evaluation of available literature includes reviews of 252 reports, including 34 literature review or summary reports and 218 detailed reports. Evaluation of many individual documentation elements indicates that the available literature does not properly document research to a degree that would establish that existing data are valid, comparable, or technically defensible for regional or national synthesis. Furthermore, when individual metadata requirements are combined, the proportion of available reports that meet these multiple criteria quickly decreases to the point where regional or national synthesis is not possible.

Author: Gregory Granato
Publication Year: 2003
Contact: Department of Transportation Publications Warehouse
75th Ave, 3341 Q Ardmore East
Landover, MD 20785
Tel: 301-322-5377; Fax 301-386-5394

Stormwater Best Management Practices in an Ultra-Urban Setting: Selection and Monitoring - This report builds on recent FHWA manuals by expanding and presenting additional data, design criteria, and monitoring study results on stormwater best management practices (BMPs) implemented in ultra-urban areas. An extensive literature search was performed along with a comprehensive analysis of documented information currently available, with the focus on identifying new and successful technologies for ultra-urban areas. Factors used to identify ultra-urban BMP studies included:

  • limited space available for BMP implementation (less that 1 acre)
  • drainage area imperviousness greater that 50 percent
  • property value of land more than $20 per square foot
  • location of BMP in right-of-way (only available space)
  • existence of build-out conditions at the site (lot-line to lot-line development)

The purpose of this report is to provide a planning-level review of the applicability and use of new and more traditional BMPs in ultra-urban areas. This report focuses on the unique characteristics specific to ultra-urban settings and provides specific guidance for selecting and siting stormwater management technologies. The information is structured in an informative, user-friendly format, with case studies highlighting examples of BMP monitoring throughout the country and tables illustrating the characteristics of each BMP to facilitate comparison and identification of specific technologies appropriate to a given site. BMP information is provided in fact sheets, which address applicability, effectiveness, siting and design, maintenance, and cost considerations. The report is organized into separate chapters that address ultra-urban considerations, BMP design information tailored to the ultra-urban environment, monitoring program design, and BMP selection.

Author: Leslie Shoemaker, Mohammed Lahlou, Amy Doll, Patricia Cazenas
Publication Year: 2002
Contact: Department of Transportation Publications Warehouse
75th Ave, 3341 Q Ardmore East
Landover, MD 20785
Tel: 301-322-5377; Fax 301-386-5394

Guidance Manual for Monitoring Highway Runoff Water Quality - This document provides guidance for selecting and using stormwater runoff monitoring equipment for monitoring of highway runoff. The guidance provided is intended to help achieve stormwater monitoring program goals through the collection of more useful and representative rainfall, flow, and water quality information that will ultimately lead to better highway runoff management decisionmaking.

Author: Eric Strecker, Lynn Mayo, Marcus Quigley, Jim Howell
Publication Year: 2001

Quantifying the Components of Impervious Surfaces - The objectives of this study are to (1) determine the makeup of total area and the relative contribution of individual components; and (2) assess the accuracy of various techniques in use for determining total impervious area. Six urban and suburban watersheds were selected for study that represent a wide geographic distribution across the country. High-resolution orthoimagery (1meter or better) was obtained for each watershed. Six classes of impervious cover were manually digitized as polygon features in a geographic information systems (GIS) environment. Relevant GIS data were obtained from County or City GIS departments. The six classes of cover were roads, buildings, parking lots, driveways, sidewalks, and other (such as sport courts). Quality control was provided by independent validation and mapping spot checks. The total area for each impervious surface class was totaled for the six watersheds and the percentage of each class was calculated against the total area of impervious cover. The largest area class of impervious cover was buildings at 29.1percent, followed by roads (28.3 percent), and parking lots (24.8 percent); with the remaining three totaling 14-percent - driveways, sidewalks, and other, where other were any other features that were not contained within the first five.

Author: Janet S. Tilley and E. Terrence Slonecker
Publication Year: 2007

Is Highway Runoff a Serious Problem? - This document is an FHWA Technical Brief that addresses the nature of and extent to which stormwater runoff from highways is a problem.

EPA Toxic Determination of Compound in Road Salt - In October 2003, the Environmental Protection Agency (EPA) classified Ferric Ferrocyanide (FFC), more commonly known as "Prussian Blue", as one of the "cyanides" on the Toxic Pollutant List under Section 307(a) of the Clean Water Act.

Great Lakes Stormwater Workshop, August 10, 2006 - This page provides an overview of a 2006 workshop convened by FHWA to address the issues presented by stormwater runoff in the Great Lakes region.

Guidance on 23 U.S.C. §328 Environmental Restoration and Pollution Abatement, August 17, 2006 - In 2005, the President signed into law the Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users (SAFETEA-LU). Among its provisions, SAFETEA-LU expanded the eligibility of Federal-aid funds for environmental restoration and pollution abatement under §6006 23 U.S.C. § 328.

Questions and feedback should be directed to Marlys Osterhues (marlys.osterhues@dot.gov, 202-366-2052).

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