National Highway Runoff Water-Quality Data and Methodology Synthesis

Project Products Released as USGS Open-File Reports Pending Publication as FHWA Reports

Approved reports include:

Bent, G.C., Gray, J.R., Smith, K.P., and Glysson, G.D., 2001, A synopsis of technical issues for monitoring sediment in highway and urban runoff: U.S. Geological Survey Open File Report 00-497, 51 p.

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Abstract
Accurate and representative sediment data are critical for assessing the potential effects of highway and urban runoff on receiving waters. The U.S. Environmental Protection Agency identified sediment as the most widespread pollutant in the Nation's rivers and streams, affecting aquatic habitat, drinking water treatment processes, and recreational uses of rivers, lakes, and estuaries. Representative sediment data are also necessary for quantifying and interpreting concentrations, loads, and effects of trace elements and organic constituents associated with highway and urban runoff. Many technical issues associated with the collecting, processing, and analyzing of samples must be addressed to produce valid (useful for intended purposes), current, complete, and technically defensible data for local, regional, and national information needs. All aspects of sediment data-collection programs need to be evaluated, and adequate quality-control data must be collected and documented so that the comparability and representativeness of data obtained for highway- and urban-runoff studies may be assessed.

Collection of representative samples for the measurement of sediment in highway and urban runoff involves a number of interrelated issues. Temporal and spatial variability in runoff result from a combination of factors, including volume and intensity of precipitation, rate of snowmelt, and features of the drainage basin such as area, slope, infiltration capacity, channel roughness, and storage characteristics. In small drainage basins such as those found in many highway and urban settings, automatic samplers are often the most suitable method for collecting samples of runoff for a variety of reasons. Indirect sediment-measurement methods are also useful as supplementary and(or) surrogate means for monitoring sediment in runoff. All of these methods have limitations in addition to benefits, which must be identified and quantified to produce representative data. Methods for processing raw sediment samples (including homogenization and subsampling) for subsequent analysis for total suspended solids or suspended-sediment concentration often increase variance and may introduce bias. Processing artifacts can be substantial if the methods used are not appropriate for the concentrations and particle-size distributions present in the samples collected.

Analytical methods for determining sediment concentrations include the suspended-sediment concentration and the total suspended solids methods. Although the terms suspended-sediment concentration and total suspended solids are often used interchangeably to describe the total concentration of suspended solid-phase material, the analytical methods differ and can produce substantially different results. The total suspended solids method, which commonly is used to produce highway- and urban-runoff sediment data, may not be valid for studies of runoff water quality. Studies of fluvial and highway-runoff sediment data indicate that analyses of samples by the total suspended solids method tends to under represent the true sediment concentration, and that relations between total suspended solids and suspended-sediment concentration are not transferable from site to site even when grain-size distribution information is available. Total suspended solids data used to calculate suspended-sediment loads in highways and urban runoff may be fundamentally unreliable. Consequently, use of total suspended solids data may have adverse consequences for the assessment, design, and maintenance of sediment-removal best management practices. Therefore, it may be necessary to analyze water samples using the suspended-sediment concentration method. Data quality, comparability, and utility are important considerations in collection, processing, and analysis of sediment samples and interpretation of sediment data for highway- and urban-runoff studies. Results from sediment studies must be comparable and readily transferable to be useful to resource managers and regulators. To meet these objectives, supporting ancillary information must be available to document the methods and procedures that are used and to describe quality-assurance and quality-control procedures that are used in the studies. Valid, current, and technically defensible protocols for collecting, processing, and analyzing sediment data for the determination of water quality in highway and urban runoff therefore need to be documented with
study results.

Breault, R.F., and Granato, G.E., 2000, A synopsis of technical issues for monitoring trace elements in highway and urban runoff: U.S. Geological Survey Open File Report 00-422, 67 p.

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Abstract
Trace elements, which are regulated for aquatic life protection, are a primary concern in highway- and urban-runoff studies because stormwater runoff may transport these constituents from the land surface to receiving waters. Many of these trace elements are essential for biological activity and become detrimental only when geologic or anthropogenic sources exceed concentrations beyond ranges typical of the natural environment. The Federal Highway Administration and State Transportation Agencies are concerned about the potential effects of highway runoff on the watershed scale and for the management and protection of watersheds. Transportation agencies need information that is documented as valid, current, and scientifically defensible to support planning and management decisions. There are many technical issues of concern for monitoring trace elements; therefore, trace-element data commonly are considered suspect, and the responsibility to provide data-quality information to support the validity of reported results rests with the data-collection agency.

Paved surfaces are fundamentally different physically, hydraulically, and chemically from the natural surfaces typical of most freshwater systems that have been the focus of many trace-element-monitoring studies. Existing scientific conceptions of the behavior of trace elements in the environment are based largely upon research on natural systems, rather than on systems typical of pavement runoff. Additionally, the logistics of stormwater sampling are difficult because of the great uncertainty in the occurrence and magnitude of storm events. Therefore, trace-element monitoring programs may be enhanced if monitoring and sampling programs are automated. Automation would standardize the process and provide a continuous record of the variations in flow and water-quality characteristics.

Great care is required to collect and process samples in a manner that will minimize potential contamination or attenuation of trace elements and other sources of bias and variability in the sampling process. Trace elements have both natural and anthropogenic sources that may affect the sampling process, including the sample-collection and handling materials used in many trace-element monitoring studies. Trace elements also react with these materials within the timescales typical for collection, processing and analysis of runoff samples. To study the characteristics and potential effects of trace elements in highway and urban runoff, investigators typically sample one or more operationally defined matrixes including: whole water, dissolved (filtered water), suspended sediment, bottom sediment, biological tissue, and contaminant sources. The sampling and analysis of each of these sample matrixes can provide specific information about the occurrence and distribution of trace elements in runoff and receiving waters. There are, however, technical concerns specific to each matrix that must be understood and addressed through use of proper collection and processing protocols. Valid protocols are designed to minimize inherent problems and to maximize the accuracy, precision, comparability, and representativeness of data collected. Documentation, including information about monitoring protocols, quality assurance and quality control efforts, and ancillary data also is necessary to establish data quality. This documentation is especially important for evaluation of historical trace-element monitoring data, because trace-element monitoring protocols and analysis methods have been constantly changing over the past 30 years.

Bricker, O.P., 1999, An overview of the factors involved in evaluating the geochemical effects of highway runoff on the environment: U.S. Geological Survey Open File Report 98-630, 28 p.

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Abstract
Materials washed by rain and snowmelt from highways into adjacent surface waters, ground waters, and ecosystems can pollute water and affect biota. To understand the chemical behavior of any one of these materials and its effects on the environment requires knowledge of the chemistry of the material and how it interacts with other components in the local geochemical system. An integrated watershed approach, therefore, would be the most effective method to assess the effects of highway runoff on local receiving waters. Analysis of one or a few specific contaminants will provide limited and incomplete information and may be misleading in terms of environmental effects. This report addresses the background geochemistry required to model highway runoff and to make realistic assessments of the potential effects of runoff on the environment.

Buckler, D.R., and Granato, G.E., 1999, Assessing biological effects from highway-runoff constituents: U.S. Geological Survey Open File Report 99-240, 45 p.

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Abstract
Increased emphasis on evaluation of nonpoint-source pollution has intensified the need for techniques that can be used to discern the toxicological effects of complex chemical mixtures. In response, the use of biological assessment techniques is receiving increased regulatory emphasis. When applied with documented habitat assessment and chemical analysis, these techniques can increase our understanding of the influence of environmental contaminants on the biological integrity and ecological function of aquatic communities.

The contaminants of greatest potential concern in highway runoff are those that arise from highway construction, maintenance, and use. The major contaminants of interest are deicers; nutrients; metals; petroleum-related organic compounds, such as polycyclic aromatic hydrocarbons (PAHs), benzene, toluene, ethylbenzene, and xylene (BTEX), and methyl tert-butyl ether (MTBE); sediment washed off the road surface; and agricultural chemicals used in highway maintenance.

Hundreds, if not thousands, of biological endpoints (measurable responses of living organisms) may be either directly or associatively affected by contaminant exposure. Measurable effects can occur throughout ecosystem processes across the wide range of biological complexity, ranging from responses at the biochemical level to the community level.

The challenge to the environmental scientist is to develop an understanding of the relationship of effects at various levels of biological organization in order to determine whether a causal relationship exists between chemical exposure and substantial ecological impairment. This report provides a brief history of the evolution of biological assessment techniques, a description of the major classes of contaminants that are of particular interest in highway runoff, an overview of representative biological assessment techniques, and a discussion of data-quality considerations.

Published reports with a focus on the effects of highway runoff on the local ecosystem were reviewed to provide information on (1) the suitability of the existing data for a quantitative national synthesis, (2) the methods available to study the effects of highway runoff on local ecosystems, and (3) the potential for adverse effects on the roadside environment and receiving waters. Although many biological studies have been done, the use of different methods and a general lack of sufficient documentation precludes a quantitative national synthesis on the basis of the existing data. The Federal Highway Administration, the U.S. Environmental Protection Agency, the U.S. Geological Survey, the Intergovernmental Task Force on Monitoring Water Quality, and the National Resources Conservation Service all have developed and documented methods for assessing the effects of contaminants on ecosystems in receiving waters. These published methods can be used to formulate a set of protocols to provide consistent information from highway-runoff studies.

Review of the literature indicates (qualitatively) that highway runoff (even from highways with high traffic volume) may not usually be acutely toxic. Tissue analysis and community assessments, however, indicate effects from highway-runoff sediments near discharge points (even from sites near highways with relatively low traffic volumes). At many sites, elevated concentrations of highway-runoff constituents were measured in tissues of species associated with aquatic sediments. Community assessments also indicate decreases in the diversity and productivity of aquatic ecosystems at some sites receiving highway runoff. These results are not definitive, however, and depend on many site-specific criteria that were not sufficiently documented in most of the studies reviewed.

Church, P.E., Granato, G.E., and Owens, D.W., 1999, Basic requirements for collecting, documenting, and reporting precipitation and stormwater-flow measurements: U.S. Geological Survey Open File Report 99-255, 30 p.

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Abstract
Accurate and representative precipitation and stormwater-flow data are crucial for use of highway- or urban-runoff study results, either individually or in a regional or national synthesis of stormwater-runoff data. Equally important is information on the level of accuracy and representativeness of this precipitation and stormwater-flow data. Accurate and representative measurements of precipitation and stormwater flow, however, are difficult to obtain because of the rapidly changing spatial and temporal distribution of precipitation and flows during a storm. Many hydrologic and hydraulic factors must be considered in performing the following: selecting sites for measuring precipitation and stormwater flow that will provide data that adequately meet the objectives and goals of the study, determining frequencies and durations of data collection to fully characterize the storm and the rapidly changing stormwater flows, and selecting methods that will yield accurate data over the full range of both rainfall intensities and stormwater flows.

To ensure that the accuracy and representativeness of precipitation and stormwater-flow data can be evaluated, decisions as to (1) where in the drainage system precipitation and stormwater flows are measured, (2) how frequently precipitation and stormwater flows are measured, (3) what methods are used to measure precipitation and stormwater flows, and (4) on what basis are these decisions made, must all be documented and communicated in an accessible format, such as a project description report, a data report or an appendix to a technical report, and (or) archived in a State or national records center.

A quality assurance/quality control program must be established to ensure that this information is documented and reported, and that decisions made in the design phase of a study are continually reviewed, internally and externally, throughout the study. Without the supporting data needed to evaluate the accuracy and representativeness of the precipitation and stormwater-flow measurements, the data collected and interpretations made may have little meaning.

Colman, J.A., Rice, K.C., and Willoughby, T.C. 2001, Methodology and significance of studies of atmospheric deposition in highway runoff: U.S. Geological Survey Open-File Report 01-259, 63 p.

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Abstract
Atmospheric deposition and the processes that are involved in causing and altering atmospheric deposition in relation to highway surfaces and runoff were evaluated nationwide. Wet deposition is more easily monitored than dry deposition, and data on wet deposition are available for major elements and water properties (constituents affecting acid deposition) from the inter-agency National Atmospheric Deposition Program/ National Trends Network (NADP/NTN). Many trace constituents (metals and organic compounds) of interest in highway runoff loads, however, are not included in the NADP/NTN. Dry deposition, which constitutes a large part of total atmospheric deposition for many constituents in highway runoff loads, is difficult to monitor accurately. Dry-deposition rates are not widely available.

Many of the highway-runoff investigations that have addressed atmospheric-deposition sources have had flawed investigative designs or problems with methodology. Some results may be incorrect because of reliance on time-aggregated data collected during a period of changing atmospheric emissions. None of the investigations used methods that could accurately quantify the part of highway runoff load that can be attributed to ambient atmospheric deposition. Lack of information about accurate ambient deposition rates and runoff loads was part of the problem. Samples collected to compute the rates and loads were collected without clean-sampling methods or sampler protocols, and without quality-assurance procedures that could validate the data. Mass-budget calculations comparing deposition and runoff did not consider loss of deposited material during on-highway processing. Loss of deposited particles from highway travel lanes could be large, as has been determined in labeled particle studies, because of resuspension caused by turbulence from passing traffic. Although a cause of resuspension of large particles, traffic turbulence may increase the rate of deposition for small particles and gases by impaction, especially during precipitation periods.

Ultimately, traffic and road maintenance may be determined to be the source of many constituents measured in highway runoff previously attributed to ambient atmospheric deposition. An investigative design using tracers of ambient deposition that are not present in highway traffic sources could determine conclusively what fraction of highway runoff load is contributed by ambient atmospheric deposition.

Dionne, S.G., Granato, G.E., and Tana, C.K, 1999, Method for examination and documentation of basic information and metadata from published reports relevant to the study of stormwater runoff quality: U.S. Geological Survey Open File Report 99-254, 156 p.

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Abstract
A readily accessible archive of information that is valid, current, and technically defensible is needed to make informed highway-planning, design, and management decisions. The National Highway Runoff Water-Quality Data and Methodology Synthesis (NDAMS) is a cataloging and assessment of the documentation of information relevant to highway-runoff water quality available in published reports. The report review process is based on the NDAMS review sheet, which was designed by the USGS with input from the FHWA, State transportation agencies, and the regulatory community. The report-review process is designed to determine the technical merit of the existing literature in terms of current requirements for data documentation, data quality, quality assurance and quality control (QA/QC), and technical issues that may affect the use of historical data. To facilitate the review process, the NDAMS review sheet is divided into 12 sections: (1) administrative review information, (2) investigation and report information, (3) temporal information, (4) location information (5) water-quality-monitoring information, (6) sample-handling methods, (7) constituent information, (8) sampling focus and matrix, (9) flow monitoring methods, (10) field QA/QC, (11) laboratory, and (12) uncertainty/error analysis.

This report describes the NDAMS report reviews and metadata documentation methods and provides an overview of the approach and of the quality-assurance and quality-control program used to implement the review process. Detailed information, including a glossary of relevant terms, a copy of the report-review sheets, and report-review instructions are completely documented in a series of three appendixes included with this report. Therefore the reviews are repeatable and the methods can be used by transportation research organizations to catalog new reports as they are published.

Granato, G.E., Bank, F.G., and Cazenas, P.A., 1998 Data Quality Objectives and Criteria for Basic Information, Acceptable Uncertainty, and Quality-Assurance and Quality-Control Documentation: U.S. Geological Survey Open File Report 98-394, 17 p.

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Abstract
The Federal Highway Administration and State transportation agencies have the responsibility of determining and minimizing the effects of highway runoff on water quality; therefore, they have been conducting an extensive program of water-quality monitoring and research during the last 25 years. The objectives and monitoring goals of highway runoff studies have been diverse, because the highway community must address many different questions about the characteristics and impacts of highway runoff. The Federal Highway Administration must establish that available data and procedures that are used to assess and predict pollutant loadings and impacts from highway stormwater runoff are valid, current, and technically supportable.

This report examines criteria for evaluating water-quality data and resultant interpretations. The criteria used to determine if data are valid (useful for intended purposes), current, and technically supportable are derived from published materials from the Federal Highway Administration, the U.S. Environmental Protection Agency, the Intergovernmental Task Force on Monitoring Water Quality, the U.S. Geological Survey and from technical experts throughout the U.S. Geological Survey.

This report examines criteria for evaluating water-quality data and resultant interpretations. The criteria used to determine if data are valid (useful for intended purposes), current, and technically supportable are derived from published materials from the Federal Highway Administration, the U.S. Environmental Protection Agency, the Intergovernmental Task Force on Monitoring Water Quality, the U.S. Geological Survey and from technical experts throughout the U.S. Geological Survey.

Granato, G.E., Driskell, T.R., and Nunes, Catherine, 2000, CHEMICAL HELP--A computer help application for classification and identification of stormwater constituents: U.S. Geological Survey Open-File Report 00-468, 10 p. 

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For Information on how to download the ChemHelp software, and related files click here:  ChemHelp

Abstract
A computer application called Chemical Help was developed to facilitate review of reports for the National Highway Runoff Water-Quality Data and Methodology Synthesis (NDAMS). The application provides a tool to quickly find a proper classification for any constituent in the NDAMS review sheets. Chemical Help contents include the name of each water-quality property, constituent, or parameter, the section number within the NDAMS review sheet, the organizational levels within a classification hierarchy, the database number, and where appropriate, the chemical formula, the Chemical Abstract Service (CAS) number, and a list of synonyms (for the organic chemicals). Therefore, Chemical Help provides information necessary to research available reference data for the water-quality properties and constituents of potential interest in stormwater studies. Chemical-Help is implemented in the Microsoft-help system interface. [Computer files for the use and documentation of Chemical Help are included on an accompanying diskette.]

Granato, G.E., and Tessler, Steven, 2001, Data model and relational database design for highway runoff water-quality metadata: U.S. Geological Survey Open-File Report 00-480, 27 p.

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Download the map of the database Database Design Plate a (200k) PDF file. To download the database-design file click here (a 2400K MS Access file). To download the data dictionary click here (a 500K MS Access file).

Abstract
A National highway and urban runoff water-quality metadatabase was developed by the U.S. Geological Survey in cooperation with the Federal Highway Administration as part of the National Highway Runoff Water-Quality Data and Methodology Synthesis (NDAMS). The database was designed to catalog available literature and to document results of the synthesis in a format that would facilitate current and future research on highway and urban runoff. This report documents the design and implementation of the NDAMS relational database, which was designed to provide a catalog of available information and the results of an assessment of the available data.

All the citations and the metadata collected during the review process are presented in a stratified metadatabase that contains citations for relevant publications, abstracts (or previa), and report-review metadata for a sample of selected reports that document results of runoff quality investigations. The database is referred to as a metadatabase because it contains information about available data sets rather than a record of the original data. The database contains the metadata needed to evaluate and characterize how valid, current, complete, comparable, and technically defensible published and available information may be when evaluated for application to the different data-quality objectives as defined by decision makers. This database is a relational database, in that all information is ultimately linked to a given citation in the catalog of available reports. The main database file contains 86 tables consisting of 29 data tables, 11 association tables, and 46 domain tables. The data tables all link to a particular citation, and each data table is focused on one aspect of the information collected in the literature search and the evaluation of available information.

This database is implemented in the Microsoft (MS) Access database software because it is widely used within and outside of government and so, is familiar to many existing and potential customers. The stratified metadatabase design for the NDAMS program is implemented in the MS Access file DBDESIGN.mdb and documented using the NDAMS_DD.mdb file recorded on the CD-ROM. The data dictionary file includes complete documentation of the table names, table descriptions, and information about each of the 419 fields in the database.

Granato, G.E., 1999, Computer Program for Point Location and Calculation of ERror (PLACER):U.S. Geological Survey Open File Report 99-99, 36 p.

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For Information on how to download the PLACER software, and related files click here:   PLACER

Abstract
A program designed for point location and calculation of error (PLACER) was developed as part of the Quality Assurance Program of the Federal Highway Administration/U.S. Geological Survey (USGS) National Data and Methodology Synthesis (NDAMS) review process. The program provides a standard method to derive study-site locations from site maps in highway-runoff, urban-runoff, and other research reports. This report provides a guide for using PLACER, documents methods used to estimate study-site locations, documents the NDAMS Study-Site Locator Form, and documents the FORTRAN code used to implement the method.

PLACER is a simple program that calculates the latitude and longitude coordinates of one or more study sites plotted on a published map and estimates the uncertainty of these calculated coordinates. PLACER calculates the latitude and longitude of each study site by interpolating between the coordinates of known features and the locations of study sites using any consistent, linear, user-defined coordinate system. This program will read data entered from the computer keyboard and(or) from a formatted text file, and will write the results to the computer screen and to a text file. PLACER is readily transferable to different computers and operating systems with few (if any) modifications because it is written in standard FORTRAN. PLACER can be used to calculate study site locations in latitude and longitude, using known map coordinates or features that are identifiable in geographic information data bases such as USGS Geographic Names Information System, which is available on the World Wide Web.

Jones, B.E., 1999, Principles and Practices for Quality Assurance and Quality Control: U.S. Geological Survey Open File Report 98-636, 17 p.

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Abstract
Quality assurance and quality control are vital parts of highway runoff water-quality monitoring projects. To be effective, project quality assurance must address all aspects of the project, including project management responsibilities and resources, data quality objectives, sampling and analysis plans, data-collection protocols, data quality-control plans, data-assessment procedures and requirements, and project outputs. Quality control ensures that the data quality objectives are achieved as planned. The historical development and current state of the art of quality assurance and quality control concepts described in this report can be applied to evaluation of data from prior projects.

Lopes, T.J., and Dionne, S.G., 1998, A Review of Semivolatile and Volatile Organic Compounds in Highway Runoff and Urban Stormwater: U.S. Geological Survey Open File Report 98-409, 67 p.

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Abstract
Many studies have been conducted since 1970 to characterize concentrations of semivolatile organic compounds (SVOCs) in highway runoff and urban stormwater. To a lesser extent, studies also have characterized concentrations of volatile organic compounds (VOCs), estimated loads ofSVOCs, and assessed potential impacts of these contaminants on receiving streams. This review evaluates the quality of existing data on SVOCs and VOCs in highway runoff and urban storm water and summarizes significant findings. Studies related to highways are emphasized when possible. The review included 44 articles and reports that focused primarily on SVOCs and VOCs. Only 17 of these publications are related to highways, and 5 of these 17 are themselves review papers. SVOCs in urban stormwater and sediments during the late 1970’s to mid-1980’s were the subject of most studies.

Criteria used to evaluate data quality included documentation of sampling protocols, analytical methods, minimum reporting limit (MRL) or method detection limit (MDL), quality-assurance protocols, and quality-control samples. The largest deficiency in documenting data quality was that only 10 percent of the studies described where water samples were collected in the stream cross section. About 80 percent of SVOCs in runoff are in the suspended solids. Because suspended solids can vary significantly even in narrow channels, concentrations from discrete point samples and contaminant loads estimated from those samples are questionable without information on sample location or how well of samplers, or use of field quality-control samples. Comparing results of different studies and evaluating the quality of environmental data, especially for samples with low concentrations, is difficult without this information.

The most significant factor affecting SVOC concentrations in water is suspended solids concentration. In sediment, the most significant factors affecting SVOC concentrations are organic carbon content and distance from sources such as highways and power plants. Petroleum hydrocarbons, oil and grease, and polycyclic aromatic hydrocarbons (PAHs) in crankcase oil and vehicle emissions are the major SVOCs detected in highway runoff and urban stormwater.

The few loading factors and regression equations that were developed in the 1970's and 1980's have limited use in estimating current (1998) loads of SVOCs on a national scale. These factors and equations are based on few data and use inconsistent units, and some are independent of rainfall. Also, more cars on the road today have catalytic converters, and fuels that were used in 1998 are cleaner than when loading factors and regression equations were developed.

Comparisons to water-quality and sediment-quality criteria and guidelines indicate that PAHs, phenolic compounds, and phthalates in runoff and sediment exceeded U.S. Environmental Protection Agency drinking-water and aquatic-life standards and guidelines. PAHs in stream sediments adjacent to highways have the highest potential for adverse effects on receiving streams.

Few data exist on VOCs in highway runoff. VOCs were detected in precipitation adjacent to a highway in England, and chloromethane, toluene, xylenes, 1,2,4-trimethylbenzene, and 1,2,3-trichloropropane were detected in runoff from a highway in Texas. In urban stormwater, gasoline-related compounds were detected in as many as 23 percent of the samples. Land use could be the most significant factor affecting the occurrence of VOCs, with highest concentrations of VOCs found in industrial areas. Temperature is another factor affecting the occurrence and concentrations of VOCs. Urban land surfaces are the primary nonpoint source of VOCs in stormwater. However, the atmosphere is a potential source of hydrophilic VOCs in stormwater, especially during cold seasons when partitioning of VOCs from air into water is greatest. Tetrachloroethene, dichloromethane, and benzene were the only VOCs detected in stormwater that exceeded U.S. Environmental Protection Agency drinking-water standards.

Smieszek, T.W., and Granato, G.E., 2000, Geographic information for analysis of highway runoff-quality data on a national or regional scale in the conterminous United States: U.S. Geological Survey Open-File Report 00-432 15 p.

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Abstract
Spatial data are important for interpretation of water-quality information on a regional or national scale. Geographic information systems (GIS) facilitate interpretation and integration of spatial data. The geographic information and data compiled for the conterminous United States during the National Highway Runoff Water-Quality Data and Methodology Synthesis project is described in this document, which also includes information on the structure, file types, and the geographic information in the data files. This "geodata" directory contains two subdirectories, labeled "gisdata" and "gisimage." The "gisdata" directory contains ArcInfo coverages, ArcInfo export files, shapefiles (used in ArcView), Spatial Data Transfer Standard Topological Vector Profile format files, and meta files in subdirectories organized by file type. The "gisimage" directory contains the GIS data in common image-file formats. The spatial geodata includes two rain-zone region maps and a map of national ecosystems originally published by the U.S. Environmental Protection Agency; regional estimates of mean annual streamflow, and water hardness published by the Federal Highway Administration; and mean monthly temperature, mean annual precipitation, and mean monthly snowfall modified from data published by the National Climatic Data Center and made available to the public by the Oregon Climate Service at Oregon State University. These GIS files were compiled for qualitative spatial analysis of available data on a national and(or) regional scale and therefore should be considered as qualitative representations, not precise geographic location information.

Tasker, G.D. and Granato, G.E., 2000, Statistical approaches to interpretation of local, regional, and national highway-runoff and urban-stormwater data: U.S. Geological Survey Open-File Report 00-491, 59 p.

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Abstract
Decision makers need viable methods for the interpretation of local, regional, and national-highway runoff and urban-stormwater data including flows, concentrations and loads of chemical constituents and sediment, potential effects on receiving waters, and the potential effectiveness of various best management practices (BMPs). Valid (useful for intended purposes), current, and technically defensible stormwater-runoff models are needed to interpret data collected in field studies, to support existing highway and urban-runoff-planning processes, to meet National Pollutant Discharge Elimination System (NPDES) requirements, and to provide methods for computation of Total Maximum Daily Loads (TMDLs) systematically and economically. 

Historically, conceptual, simulation, empirical, and statistical models of varying levels of detail, complexity, and uncertainty have been used to meet various data-quality objectives in the decision making processes necessary for the planning, design, construction, and maintenance of highways and for other land-use applications. Water-quality simulation models attempt a detailed representation of the physical processes and mechanisms at a given site. Empirical and statistical regional water-quality assessment models provide a more general picture of water quality or changes in water quality over a region. All these modeling techniques share one common aspect--their predictive ability is poor without suitable site-specific data for calibration. 

To properly apply the correct model, one must understand the classification of variables, the unique characteristics of water-resources data, and the concept of population structure and analysis. Classifying variables being used to analyze data may determine which statistical methods are appropriate for data analysis. An understanding of the characteristics of water-resources data is necessary to evaluate the applicability of different statistical methods, to interpret the results of these techniques, and to use tools and techniques that account for the unique nature of water-resources data sets. Populations of data on stormwater-runoff quantity and quality are often best modeled as logarithmic transformations. Therefore, these factors need to be considered to form valid, current, and technically defensible stormwater-runoff models.

Regression analysis is an accepted method for interpretation of water-resources data and for prediction of current or future conditions at sites that fit the input data model. Regression analysis is designed to provide an estimate of the average response of a system as it relates to variation in one or more known variables. To produce valid models, however, regression analysis should include visual analysis of scatterplots, an examination of the regression equation, evaluation of the method design assumptions, and regression diagnostics. A number of statistical techniques are described in the text and in the appendixes to provide information necessary to interpret data by use of appropriate methods.

Uncertainty is an important part of any decision-making process. In order to deal with uncertainty problems, the analyst needs to know the severity of the statistical uncertainty of the methods used to predict water quality. Statistical models need to be based on information that is meaningful, representative, complete, precise, accurate, and comparable to be deemed valid, up to date, and technically supportable. To assess uncertainty in the analytical tools, the modeling methods, and the underlying data set, all of these components need be documented and communicated in an accessible format within project publications.

Project Products Released as USGS Open-File Reports Pending Publication as FHWA Reports

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