United States Office of Water (4303) EPA-821-R-99-012

Environmental Protection Washington, DC 20460 August 1999

Agency

Preliminary Data Summary of

Urban Storm Water

Best Management Practices
i

Acknowledgments

This report was prepared by Eric Strassler, Project Manager, Jesse Pritts, Civil Engineer,

and Kristen Strellec, Economist, of the Engineering and Analysis Division, Office of Science and

Technology. Assistance was provided by Parsons Engineering Science, Inc., Limno-Tech, Inc.

and the Center for Watershed Protection under EPA Contract No. 68-C6-0001. EPA reviewers

were Eugene Bromley, Rod Frederick, John Kosco, Marjorie Pitts, Marvin Rubin, Steven

Sweeney and Kathy Zirbser. EPA thanks its external reviewers for this report:

George Aponte Clarke, Natural Resources Defense Council

Edward U. Graham, P.E., and John Galli, Metropolitan Washington Council of

Governments

Jonathan E. Jones, P.E., Wright Water Engineers, Inc.

Eric H. Livingston, Florida Department of Environmental Protection

Eric W. Strecker, P.E., URS Greiner Woodward-Clyde

Lori L. Sundstrom, City of Phoenix, AZ

Ben Urbonas, P.E., Urban Drainage and Flood Control District, Denver.

Disclaimer

Mention of trade names or commercial products does not constitute endorsement by EPA or

recommendation for use.
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Table of Contents

List of Tables ........................................................ iv

List of Figures ........................................................ v

1.0 Summary .......................................................... 1-1

2.0 Introduction and Scope ............................................... 2-1

2.1 Effluent Guidelines Program and Consent Decree Requirements ........... 2-1

2.2 Types of Discharges Addressed ................................... 2-2

2.3 Data Sources and Data Collection Techniques ........................ 2-3

3.0 Existing Storm Water Regulations and Permits .............................. 3-1

3.1 Phase I NPDES ............................................... 3-1

3.2 Phase II NPDES ............................................... 3-2

3.3 Coastal Zone Act Requirements ................................... 3-3

3.4 Regional, State and Local Programs ................................ 3-4

4.0 Environmental Assessment ............................................. 4-1

4.1 Overview of Storm Water Discharges ............................... 4-3

4.2 Pollutants in Urban Storm Water .................................. 4-6

4.2.1 Solids, Sediment and Floatables ............................ 4-11

4.2.2 Oxygen-Demanding Substances and Dissolved Oxygen ........... 4-12

4.2.3 Nitrogen and Phosphorus ................................. 4-13

4.2.4 Pathogens ............................................. 4-13

4.2.5 Petroleum Hydrocarbons .................................. 4-15

4.2.6 Metals ................................................ 4-16

4.2.7 Synthetic Organic Compounds ............................. 4-18

4.2.8 Temperature ........................................... 4-19

4.2.9 pH .................................................. 4-22

4.3 Reported Impacts of Urban Storm Water ........................... 4-23

4.3.1 Flow Impacts .......................................... 4-23

4.3.2 Habitat Impacts ......................................... 4-32

4.3.3 Public Health Impacts .................................... 4-44

4.3.4 Aesthetic Impacts ....................................... 4-48

5.0 Description and Performance of Storm Water Best Management Practices ......... 5-1

5.1 Goals of Storm Water Best Management Practices ..................... 5-1

5.1.1 Flow Control ........................................... 5-1

5.1.2 Pollutant Removal ........................................ 5-4

5.1.3 Pollutant Source Reductions ................................ 5-6

5.2 Types of Storm Water Best Management Practices ..................... 5-7

5.2.1 Structural BMPs ......................................... 5-7
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5.2.2 Non-Structural BMPs .................................... 5-30

5.2.3 Low-Impact Development Practices ......................... 5-39

5.3 BMP Selection ............................................... 5-41

5.4 Monitoring BMP Effectiveness ................................... 5-42

5.4.1 Water Quality Monitoring of BMPs ......................... 5-43

5.4.2 Receiving Stream Assessments ............................. 5-46

5.5 Effectiveness of BMPs in Managing Urban Runoff .................... 5-46

5.5.1 Controlling Pollution Generation ............................ 5-48

5.5.2 Controlling Pollution Discharges ............................ 5-50

5.5.3 Controlling Flow Impacts ................................. 5-83

5.6 Conclusions ................................................. 5-85

6.0 Costs and Benefits of Storm Water BMPs ................................. 6-1

6.1 Structural BMP Costs ........................................... 6-1

6.1.1 Base Capital Costs ....................................... 6-2

6.1.2 Design, Contingency and Permitting Costs .................... 6-13

6.1.3 Land Costs ............................................ 6-13

6.1.4 Operation and Maintenance Costs ........................... 6-14

6.1.5 Long-Term BMP Costs: Two Scenarios ...................... 6-16

6.1.6 Adjusting Costs Regionally ................................ 6-19

6.2 Non-Structural BMP Costs ...................................... 6-21

6.2.1 Street Sweeping ........................................ 6-21

6.2.2 Illicit Connection Identification and Elimination ................ 6-22

6.2.3 Public Education and Outreach ............................. 6-22

6.2.4 Land Use Modifications .................................. 6-25

6.2.5 Oil and Hazardous Waste Collection ......................... 6-27

6.2.6 Proper Storage of Materials ............................... 6-27

6.3 Benefits of Storm Water BMPs .................................. 6-28

6.3.1 Storm Water Pollutant Reduction ........................... 6-28

6.3.2 Hydrological and Habitat Benefits ........................... 6-32

6.3.3 Human Health Benefits ................................... 6-37

6.3.4 Additional and Aesthetic Benefits ........................... 6-37

6.4 Review of Economic Analysis of the NPDES Phase II Storm Water Rule ... 6-38

6.4.1 Analyses of Potential Costs ................................ 6-39

6.4.2 Assessment of Potential Benefits ............................ 6-41

6.4.3 Comparison of Benefits and Costs ........................... 6-42

6.5 Financial Issues ............................................... 6-42

6.5.1 Municipal Financing of Storm Water Programs ................. 6-43

6.6 Summary ................................................... 6-44

References ............................................................... R-1

Index ................................................................... I-1
iv

List of Tables

4-1. Median Event Mean Concentrations for Urban Land Uses ....................... 4-8

4-2. Sources of Contaminants in Urban Storm Water Runoff ........................ 4-9

4-3. Typical Pollutant Loadings from Runoff by Urban Land Use (lbs/acre-yr) .......... 4-10

4-4. Comparison of Water Quality Parameters in Urban Runoff with Domestic Wastewater

................................................................ 4-11

4-5. Densities of Selected Pathogens and Indicator Microorganisms in Storm Water in Baltimore,

Maryland Area ..................................................... 4-15

4-6. Fecal Coliform Concentrations Collected in Sheetflow from Urban Land Uses ....... 4-15

4-7. Most Frequently Detected Priority Pollutants in Nationwide Urban Runoff Program Samples

(1978-83) ......................................................... 4-17

4-8. Probability of Event Mean Concentration of Constituents in Wisconsin Storm Water

Exceeding Wisconsin Surface Water and Ground Water Quality Standards: Metals

................................................................ 4-18

4-9. Probability of Event Mean Concentration of Constituents in Wisconsin Storm Water

Exceeding Wisconsin Surface Water and Ground Water Quality Standards: Synthetic

Organic Compounds ................................................ 4-19

4-10. Impacts from Increases in Impervious Surfaces ............................. 4-26

4-11. Comparison of Estimated Runoff Volume and Peak Discharge for Developed and

Undeveloped Areas ................................................. 4-27

4-12. Percent Increase of Two-Year Flood, Bankfull Width, and Bankfull Depth from PreDevelopment Conditions to Urbanized Conditions (Based on Modeling Results) ... 4-30

4-13. Average Percent Base Flow of Selected Streams on Long Island by Area ......... 4-32

4-14. Water Quality Parameters Affecting Habitat ............................... 4-35

4-15. Relative Toxicities of Samples Using Microtox® Measurement Method ........... 4-37

4-16. Delaware Insect Population Abundance by Degree of Urbanization .............. 4-40

4-17. Relative Abundance of Native and Introduced Fish in Urbanized and Non-Urbanized Areas

in Coyote Creek, California ........................................... 4-42

4-18. Effects of Urbanization on the Fish Community of Tuckahoe Creek, Virginia ...... 4-44

4-19. Comparative Health Outcomes for Swimming in Front of Drains in Santa Monica Bay

................................................................ 4-47

5-1. Percent Runoff Volumes Contributed by Source Area in Two Urbanized Areas of Wisconsin

................................................................ 5-34

5-2. Contaminant Load Percentages in Two Urbanized Areas of Wisconsin ............ 5-35

5-3. Recommended BMP Maintenance Schedules ................................ 5-38

5-4. Sources of Storm Water Runoff and BMP Monitoring Data .................... 5-47

5-5. Monitoring Studies for BMP Categories ................................... 5-51

5-6. Extent of Monitoring for Selected Pollutants in BMP Performance Studies ......... 5-52

5-7. Structural BMP Expected Pollutant Removal Efficiency ....................... 5-54

5-8. Pollutant Removal Efficiency of Infiltration Practices .......................... 5-55

5-9. Pollutant Removal Efficiency of Retention Basins ............................ 5-57

5-10. Summary of Prince William Parkway Regional Wet Pond Sampling Data .......... 5-62
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5-11. Pollutant Removal Efficiency of Constructed Wetland Systems ................. 5-68

5-12. Summary of Crestwood Marsh Constructed Wetland Sampling Data ............. 5-72

5-13. Pollutant Removal Efficiency of Storm Water Filtration Systems ................ 5-75

5-14. Summary of Hollywood Branch Peat/Sand Filter Storm Event Sampling Data ...... 5-80

5-15. Summary of Hollywood Branch Peat/Sand Filter Baseflow Sampling Data ......... 5-81

5-16. Pollutant Removal Efficiency of Open Channel Vegetated Systems .............. 5-82

6-1. Typical Base Capital Construction Costs for BMPs ............................ 6-3

6-2. Base Costs of Typical Applications of Storm Water BMPs ...................... 6-4

6-3. Regional Cost Adjustment Factors ......................................... 6-5

6-4. Base Capital Costs for Storm Water Ponds and Wetlands ....................... 6-7

6-5. Base Capital Costs for Infiltration Practices .................................. 6-9

6-6. Construction Costs for Various Sand Filters ................................ 6-12

6-7. Base Capital Costs of Vegetative BMPs ................................... 6-13

6-8. Design, Contingency and Permitting Costs .................................. 6-13

6-9. Relative Land Consumption of Storm Water BMPs ........................... 6-14

6-10. Annual Maintenance Costs ............................................ 6-15

6-11. Data for the Commercial Site Scenario ................................... 6-17

6-12. BMP Costs for a Five Acre Commercial Development ........................ 6-18

6-13. Data for the Residential Site Scenario .................................... 6-19

6-14. BMP Costs for a Thirty-Eight Acre Residential Development .................. 6-20

6-15. Street Sweeper Cost Data ............................................. 6-21

6-16. Annualized Sweeper Costs ............................................ 6-22

6-17. Public Education Costs in Seattle, Washington ............................. 6-23

6-18. Unit Program Costs for Public Education Programs .......................... 6-24

6-19. Comparison of Capital Costs of Municipal Infrastructure for a Single Dwelling Unit

................................................................ 6-26

6-20. Impervious Cover Reduction and Cost Savings of Conservation Development ...... 6-27

6-21. Non-Structural BMPs Suited to Controlling Various Pollutants ................. 6-29

List of Figures

4-1. Effects of Imperviousness on Runoff and Infiltration ........................... 4-4

4-2. Effects of Siltation on Rivers and Streams .................................. 4-12

4-3. Relationship Between Increasing Imperviousness and Urban Stream Temperature .... 4-21

4-4. Relationship Between Watershed Imperviousness and Baseflow Water Temperature . . 4-22

4-5. Proportions of Impaired Water Bodies Attributed to Urban Runoff ............... 4-23

4-6. Relationship of Watershed Imperviousness to Runoff Coefficient Levels ........... 4-25

4-7. Effect of Urbanization on Stream Slope and Flooding ......................... 4-28

4-8. Hydrographs for Urban and Non-Urban Streams ............................. 4-29

4-9. Sediment Loadings on Small Streams in Wisconsin ........................... 4-31

4-10. Relationship Between Urban Storm Water and Aquatic Ecosystems ............. 4-33

4-11. Relationship Between Impervious Cover and Stream Quality ................... 4-34
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4-12. Low pH Tolerance by Different Species ................................... 4-36

4-13. Comparison of a Healthy Stream Bank and an Eroding Bank ................... 4-38

4-14. Effects of Sediment Deposits on Macroinvertebrates in Juday Creek, Indiana ....... 4-41

4-15. Average Densities of Fish Eggs and Larvae in New York ...................... 4-43

4-16. Health Effects Observed Relative to Distance from Santa Monica Bay Storm Drains

................................................................ 4-46

4-17. Sources Associated with Shellfish Harvesting Restrictions, in Percent ............ 4-48

5-1. Infiltration Basin ..................................................... 5-10

5-2. Porous Pavement System ............................................... 5-11

5-3. Infiltration Trench .................................................... 5-12

5-4. Detention Basin ...................................................... 5-13

5-5. Retention Pond ...................................................... 5-15

5-6. Constructed Wetland System ............................................ 5-17

5-7. Filter Media ......................................................... 5-18

5-8. Austin Full Sedimentation-Filtration System ................................ 5-19

5-9. Underground Vault Sand Filter .......................................... 5-20

5-10. Delaware Sand Filter ................................................. 5-21

5-11. Alexandria Compound Filter ........................................... 5-22

5-12. Bioretention System ................................................. 5-24

5-13. Grass Filter Strip .................................................... 5-27

5-14. Prince William Parkway Regional Wet Pond ............................... 5-61

5-15. Crestwood Marsh Constructed Wetland .................................. 5-71

5-16. Hollywood Branch Peat/Sand Filter ...................................... 5-78

6-1. Rainfall Zones of the United States ........................................ 6-6

6-2. Retention Basin Construction Cost ........................................ 6-8

6-3. Infiltration Trench Cost ................................................ 6-10

6-4. Infiltration Basin Construction Cost ....................................... 6-11

6-5. Changes in Pollutant Load Associated with a Public Education Program ........... 6-25

6-6. Effects of Impervious Cover on Stream Quality .............................. 6-33

6-7. Stormwater Control Points Along the Rainfall Frequency Spectrum ............... 6-34
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1.0 Summary

The significance of storm water runoff in affecting water quality in the United States has

become an increasing concern in recent years, as further improvements are made in controlling

other point sources such as municipal sewage and industrial waste. EPA conducted a broad

analysis of storm water runoff characteristics in its Nationwide Urban Runoff Program between

1979 and 1983. During the 1980's the Agency made several attempts to promulgate regulatory

controls for storm water runoff under the statutory framework of the 1972 Clean Water Act. 

Following enactment of the Water Quality Act of 1987, EPA began development of a more

comprehensive regulatory program. During the course of these actions, the use of best

management practices (BMPs) in addressing runoff problems was frequently identified, however it

was known that additional research on the performance of BMPs was also needed.

EPA's Engineering and Analysis Division conducted a study on storm water best

management practices during 1997 and 1998 as part of its series of preliminary studies in the

effluent guidelines program. This report summarizes existing information and data regarding the

effectiveness of BMPs to control and reduce pollutants in urban storm water. The report

provides a synopsis of what is currently known about the expected costs and environmental

benefits of BMPs, and identifies information gaps as well.

Detailed information about BMP design is beyond the scope of this report. Readers are

encouraged to consult the wide range of storm water BMP design manuals available from states

and localities and other organizations for detailed design guidelines. Information regarding BMP

performance and selection is also provided in other EPA documents, such as Guidance Specifying

Management Measure for Sources of Nonpoint Source Pollution in Coastal Water (US EPA,

1993a); Urban Runoff Pollution Prevention and Control Planning (US EPA, 1993c); and

Municipal Wastewater Management Fact Sheets: Storm Water Best Management Practices (US

EPA, 1996e). In addition, readers are encouraged to consult the ASCE/WEF Manuals of

Practice, Design and Construction of Urban Stormwater Management Systems (ASCE/WEF,

1992) and Urban Runoff Quality Management (ASCE/WEF, 1998) for a more thorough

discussion of storm water management design.

Summary of Findings

1. Waterways and receiving waters near urban and suburban areas are often adversely affected by

urban storm water runoff. Impacts may be manifested in terms of:

• alterations in hydraulic characteristics of streams receiving runoff such as higher peak

flow rates, increased frequency and duration of bankfull and sub-bankfull flows,

increased occurrences of downstream flooding, and reduced baseflow levels
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• changes in receiving stream morphology such as increased rates of sediment transport

and deposition, increased shoreline erosion, stream channel widening, and increased

stream bed scouring

• aquatic habitat impacts leading to changes in fish and macroinvertebrate populations

and loss of sensitive species

• public health and recreation impacts such as increased risk of illness due to contact

with contaminated water bodies, contamination of drinking water supplies, beach

closures, restrictions on fishing, and shellfish bed closures.

2. A wide variety of BMPs, both structural and non-structural, are available to address urban

storm water runoff and discharges.

• For various reasons (such as cost, suitability to site, etc.) some of these BMP types are

widely used, some infrequently; some are relatively new designs that are not widely in

use.

• Many BMPs are used primarily for water quantity control (i.e. to prevent flooding),

although they may provide ancillary water quality benefits.

• Some BMP types have been analyzed for performance in terms of site-specific

pollutant removal, although not extensively enough to allow for generalizations.

• The pollutant removal performance of some BMP types is essentially undocumented.

• Some BMP types, particularly non-structural and those that do not have discrete inflow

or outflow points, are difficult to monitor.

• There is no widely-accepted definition of "efficiency" or "pollutant removal" for storm

water BMPs.

• The role of chemical pollutant monitoring vs. receiving stream biological monitoring in

evaluating BMP performance is not well documented.

3. Only a few cost studies have been conducted for storm water BMPs.

• Due to the limited cost data, a lack of clear definitions of performance, and limited

"performance" data, it is difficult at this time to develop cost-effectiveness comparisons

for various BMP types.

4. The benefits of individual BMPs are site-specific and depend on a number of factors including:
1 - 3

• the number, intensity and duration of wet weather events;

• the pollutant removal efficiency of the BMP;

• the water quality and physical conditions of the receiving waters;

• the current and potential use of the receiving waters; and

• the existence of nearby “substitute” sites of unimpaired waters.

Because these factors will vary substantially from site to site, data are not available with which to

develop estimates of benefits for individual BMP types.

5. A number of researchers are continuing to work on BMP performance monitoring, and there

are several attempts underway to develop comparison frameworks through the construction of

comprehensive databases on BMP design characteristics and performance.

Organization of Report

This report is divided into six chapters. Chapter 1 presents a summary of the major

findings of the report. Chapter 2 presents a general introduction of the purposes and goals of this

evaluation. Chapter 3 summarizes existing regulations and permits developed by EPA to address

urban storm water discharges, including regulations under the National Pollutant Discharge

Elimination System (NPDES) and the Coastal Zone Act Reauthorization Amendments (CZARA). 

Chapter 4 presents an assessment of the environmental problems attributable to urban storm water

discharges and Chapter 5 identifies the best management practices that can be used to control the

quantity and improve the quality of storm water prior to discharge. Chapter 6 identifies the costs

and benefits of storm water BMPs.
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2.0 Introduction and Scope

2.1 Effluent Guidelines Program and Consent Decree Requirements

Effluent guidelines are national standards for categories of dischargers to surface waters. 

The program was established in 1972 under Title III of the Clean Water Act (CWA). Since that

time EPA has developed effluent guideline regulations for over 50 categories, primarily industrial

dischargers. In these regulations the Agency typically establishes numeric “end-of-pipe” effluent

limitations for specific chemical pollutants and/or indicator parameters (e.g. BOD, oil and grease). 

For some categories, EPA has also issued narrative requirements for best management practices

(BMPs) to address control of storm water runoff, plant maintenance schedules and training of

plant personnel. The effluent limitations are generally based on the performance of available or

demonstrated control and treatment technologies. Resulting effluent limitations are commonly

referred to as "technology-based" standards. The regulations are implemented in National

Pollutant Discharge Elimination System (NPDES) permits, which are issued by EPA and State

agencies under the authority of CWA Section 402.

The Water Quality Act of 1987 added section 304(m) to the CWA. This provision

requires EPA to publish a biennial Effluent Guidelines Plan and develop additional regulations. 

EPA’s effluent guidelines program is currently subject to a consent decree (“Decree”) in Natural

Resources Defense Council et al v. Browner (D.D.C. 89-2980, January 31, 1992, as amended).

The Decree requires the Agency to propose effluent guideline regulations and take final action for

20 point source categories, according to a specified schedule. Additionally, the Decree requires

that the Agency conduct 11 preliminary studies to assist in selecting categories for regulation

development.

The 1987 amendments also added section 402(p) to the CWA, which requires

development of a national program for regulation of storm water discharges. This is discussed

further in Chapter 3 of this report.

In 1996, the Natural Resources Defense Council (NRDC) recommended that EPA

develop effluent guidelines for categories of storm water dischargers, to supplement the existing

NPDES permit regulations covering storm water discharges. Because municipal storm water

discharges present a range of complex phenomena that have not been extensively documented in

the professional literature, and because there is a lack of generally accepted methods for

evaluating storm water management practices, EPA determined that conducting a preliminary

study would be appropriate to satisfy one of the study obligations under the Decree. This

preliminary study is intended to assist decision making on initiating regulatory development

projects.
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2.2 Types of Discharges Addressed

This study is focused on BMPs designed to prevent, control or treat storm water

discharges, and the nature and measurement of storm water discharges. Storm water discharges

may flow directly into surface waters, into municipal separate storm sewer systems (“MS4s”),

and/or infiltrate into groundwater. The emphasis on BMPs is intended to support the national

NPDES storm water program. Some aspects of the BMPs described herein may also be relevant

for other types of wet weather pollution problems, such as combined sewer overflows (CSOs).

Storm water BMPs may be organized into two major groups with multiple subgroups:

• Structural BMPs include:

> infiltration systems such as infiltration basins and porous pavement

> detention systems such as basins and underground vaults

> retention systems such as wet ponds

> constructed wetland systems

> filtration systems such as media filters and bioretention systems

> vegetated systems such as grass filter strips and vegetated swales

> minimizing directly-connected impervious surfaces

> miscellaneous and vendor-supplied systems such as oil/water separators and

hydrodynamic devices

• Non-Structural BMPs include:

> automotive product and household hazardous material disposal

> commercial and retail space good housekeeping

> industrial good housekeeping

> modified use of fertilizers, pesticides and herbicides

> lawn debris management

> animal waste disposal

> maintenance practices such as catch basin cleaning, street and parking lot

sweeping, road and ditch maintenance

> illicit discharge detection and elimination

> educational and outreach programs

> storm drain inlet stenciling

> low-impact development and land use planning.

The impacts of storm water discharges are described in Chapter 4. Various BMP designs for

addressing storm water discharges are described in Chapter 5, and the costs and economic

impacts of BMP are described in Chapter 6.
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2.3 Data Sources and Data Collection Techniques

ASCE National Stormwater BMP Database

Since 1995, EPA and the American Society of Civil Engineers (ASCE) have operated

under a cooperative agreement to develop a database of storm water BMP design and

performance. The initial version of this database provides pollutant removal data and other

performance measures on approximately 75 BMPs based on published studies and reports. These

studies and reports were carefully selected from a comprehensive screening of virtually all

available published literature on BMP performance, amounting to about 800 bibliographic

references. 

A significant objective of the database is to provide a design tool for local storm water

designers and planners. The database has the capacity to report extensive detail about the design

of BMPs, along with descriptive information about the adjacent watershed, hydrology and other

geographic data.

As of early 1999, the initial version of the database is being tested, and a public release

will be available in mid-1999. EPA and ASCE are continuing to develop the database and are

encouraging organizations that have conducted BMP monitoring to submit their findings to the

ASCE Database Clearinghouse for entry into the database. As new data are gathered, periodic

updates will be made available to the public through use of the Internet.

Center for Watershed Protection National Pollutant Removal Performance Database

In 1997, the Center for Watershed Protection developed a database for the Chesapeake

Research Consortium titled, "National Pollutant Removal Performance Database for Stormwater

BMPs" (Brown and Schueler, 1997a). This database focuses on the pollutant removal efficiency

of commonly used and innovative urban BMPs for storm water control. The database is derived

from 123 research studies developed between 1977 and 1996.

All of the studies in the database utilized data collected with automated sampling

equipment and had documented methods to compute pollutant removal efficiencies. More than

three-quarters of the studies were based on four or more storm samples, while the remaining

studies were either based on fewer than four storms or the sample size was not stated.

Literature Cited

• EPA reports including the Nationwide Urban Runoff Program (NURP), National

Water Quality Inventory, Coastal Nonpoint Pollution Program Guidance, NPDES

Rules, guidance documents and fact sheets.
2 - 4

• Other Federal agency publications from U.S. Geological Survey and U.S. Department

of Agriculture.

• Professional journals and manuals of practice such as those from ASCE and the Water

Environment Federation

• Publications of research organizations such as the Center for Watershed Protection,

Terrene Institute, Metropolitan Washington Council of Governments and the

Watershed Management Institute

• State and local government BMP design manuals.

BMP Performance Data Developed for this Preliminary Study

EPA conducted field performance evaluations at three structural BMP sites during 1998. 

While these evaluations contribute to the literature on BMP performance, EPA also intended that

the field testing would serve as an experimental framework for refining evaluation methodology.

Three sites in the Washington, D.C. area were monitored: a constructed wetland, a peat-sand

filter, and a regional wet pond. Data summaries for these monitoring activities appear in Chapter

5. Additional findings will be provided in a supplement to this report.
3 - 1

3.0 Existing Storm Water Regulations and Permits

Congress added Section 402(p) to the Clean Water Act in 1987 to require implementation

of a comprehensive approach for addressing storm water discharges in two phases. Section

402(p)(4) required EPA to develop permit application regulations under the National Pollutant

Discharge Elimination System (NPDES), submission of NPDES permit applications, issuance of

NPDES permits, and compliance with NPDES permit conditions. Section 402(p)(6) requires

EPA to designate storm water discharges to be regulated (within the statutory definitions

provided in section 402(p)(2)) and establish a comprehensive regulatory program, which may

include performance standards, guidelines, guidance, and management practices and treatment

requirements.

3.1 Phase I NPDES

EPA promulgated the first phase of NPDES storm water permit application regulations

(“Phase I”) on November 16, 1990 (US EPA, 1990). The provisions addressing MS4s cover

those systems serving a population of 100,000 or more. This includes 173 cities, 47 counties and

additional systems designated by EPA or states based on such system’s interrelationship with or

proximity to the aforementioned systems, such as state highway departments. A total of 260

permits, covering approximately 880 operators (local governments, state highway departments,

etc.) have been identified as subject to Phase I permit application requirements. As of late 1998,

approximately 228 such permits have been issued in final form.

The CWA requires that MS4 permits effectively prohibit non-storm water discharges into

the storm sewers as well as reduce the discharge of pollutants to the maximum extent practicable

(including management practices, control techniques and system, design and engineering methods,

and other provisions appropriate for the control of such pollutants).

Phase I MS4 permittees were required to submit an application that included source

identification information, precipitation data, existing data on the volume and quality of storm

water discharges, a list of receiving water bodies and existing information on impacts on receiving

waters, a field screening analysis for illicit connections and illegal dumping, and other information.

Following this submission, MS4 permittees were to gather and provide additional

information including:

• discharge characterization data based on quantitative data from 5 to 10 representative

locations in approved sampling plans; estimates of the annual pollutant load and event

mean concentration of system discharges for selected conventional pollutants and

heavy metals; a proposed schedule to provide estimates of seasonal pollutant loads; and

the mean concentration for certain detected constituents in a representative storm

event;
3 - 2

• a proposed management program including descriptions of: structural and source

control measures that are to be implemented to reduce pollutants in runoff from

commercial and residential areas; a program to detect and remove illicit discharges; and

a program to control pollutants in construction site runoff.

The Phase I rule also covers storm water discharges "associated with industrial activity." 

This includes facilities covered by effluent guidelines and other designated classes of industrial and

commercial facilities, such as hazardous waste treatment, storage, or disposal; landfills; recycling;

vehicle maintenance and equipment cleaning; sewage sludge handling; construction activity (sites

with 5 or more acres of disturbed land); and facilities where materials are exposed to storm water. 

Permittees must prepare a storm water pollution prevention plan which describes pollution

sources, measures and controls.

EPA and the states used several permit mechanisms for the many facilities receiving

NPDES permits for the first time. EPA issued "baseline" general permits to cover a wide range of

facilities with basic requirements, with the intent that more specific requirements would follow in

subsequent permit cycles. Industry-specific or "group" permits were issued based on applications

submitted by business associations, and other sites were issued individual permits.

The management and pollution prevention plans prepared by MS4s and industrial

permittees vary in their level of detail and specificity regarding design and implementation of best

management practices (BMPs). EPA and some states have issued guidance on preparation of

these plans (US EPA, 1992d; US EPA, 1992e). The Agency has not conducted a nationwide

review of these plans.

3.2 Phase II NPDES

EPA proposed the NPDES storm water regulations for the second phase of storm water

discharge control (“Phase II”) on January 9, 1998 (US EPA, 1998c). EPA is required to

promulgate the Phase II rule in 1999 under a separate consent decree.

The proposal designates two classes of facilities for automatic coverage on a nationwide

basis under the NPDES program, (1) small municipal separate storm sewer systems located in

urbanized areas (about 3,500 municipalities would be included in the program); and (2)

construction activities (pollutants include sediments and erosion from these sites) that disturb

equal to or greater than one and less than five acres of land (about 110,000 sites per year will be

included in the program). Those facilities designated above would need to apply for NPDES

storm water permits by 2002. EPA is anticipating that most permittees would be covered under

general permits.

EPA is also proposing to conditionally exclude from the NPDES storm water program

Phase I facilities that have "no exposure" of industrial activities, such as industrial products,
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processes, or raw materials, to storm water, thereby reducing application of the program to many

industrial activities currently covered by the program that have no industrial storm water

discharges.

Some facilities that EPA is proposing to cover under the Phase II rule are currently subject

to state and/or local storm water management requirements.

3.3 Coastal Zone Act Requirements

Section 6217 of the Coastal Zone Act Reauthorization Amendments (CZARA) of 1990

provides that States with approved coastal zone management programs must develop and submit

coastal nonpoint pollution control programs to EPA and the National Oceanic and Atmospheric

Administration (NOAA) for approval. Failure to submit an approvable program would result in a

reduction of federal grants to such states under both the Coastal Zone Management Act and

section 319 of the CWA.

State coastal nonpoint pollution control programs under CZARA are to include

enforceable policies and mechanisms that ensure implementation of the management measures

throughout the coastal management area. Section 6217(g)(5) defines management measures as

"economically achievable measures for the control of the addition of pollutants from existing and

new categories and classes of nonpoint sources of pollution, which reflect the greatest degree of

pollutant reduction achievable through the application of the best available nonpoint pollution

control practices, technologies, processes, siting criteria, operating methods, or other

alternatives." The amendments provide for a technology-based approach based on technical and

economic achievability under the rationale that neither States nor EPA have the money, time, or

other resources to create and expeditiously implement a program that depends on establishing

cause and effect linkages between particular land use activities and specific water quality

problems. If this technology-based approach fails to achieve and maintain applicable water quality

standards and to protect designated uses, sec. 6217(b)(3) requires additional management

measures.

EPA issued Guidance Specifying Management Measures for Sources of Nonpoint

Pollution in Coastal Waters under sec. 6217(g) in January 1993 (US EPA, 1993a). The guidance

identifies management measures for five major categories of nonpoint source pollution:

agriculture; forestry; urban; marinas and recreational boating; and hydromodification. The

management measures reflect the greatest degree of pollutant reduction that is economically

achievable for each of the listed sources. These management measures provide reference

standards for the states to use in developing or refining their coastal nonpoint programs. In

general, the management measures were written to describe systems designed to reduce the

generation of pollutants. A few management measures, however, contain quantitative standards

that specify pollutant loading reductions. For example, the new development management

measure, which is applicable to storm water runoff associated with construction in urban areas,
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requires (1) that by design or performance the average annual total suspended solid loadings be

reduced by 80 percent and (2) to the extent practicable, that the pre-development peak runoff rate

and average volume be maintained. The management measures approach was adopted to provide

state officials with flexibility in selecting strategies and management systems and practices that are

appropriate for regional or local conditions, provided that equivalent or higher levels of pollutant

control are achieved.

Storm water discharges regulated under the existing NPDES program, such as discharges

from municipal separate storm sewers serving a population of 100,000 or more and from

construction activities that disturb 5 or more acres, do not need to be addressed in Coastal

Nonpoint Pollution Control programs. However, potential new sources, such as urban

development adjacent to or surrounding municipal systems serving a population of 100,000 or

more, smaller urbanized areas, and construction sites that disturb less than 5 acres, that are

identified in management measures under section 6217 guidance need to be addressed in Coastal

Nonpoint Pollution Control Programs until such discharges are issued an NPDES permit. EPA

and NOAA have worked and continue to work together in their activities to ensure that

authorities between NPDES and CZARA do not overlap.

EPA and NOAA published Coastal Nonpoint Pollution Control Program: Program

Development and Approval Guidance (US EPA, 1993d), which addresses such issues as the basis

and process for EPA/NOAA approval of State Coastal Nonpoint Pollution Control programs,

how EPA and NOAA expect state programs to implement management measures in conformity

with EPA guidance, and procedures for reviewing and modifying state coastal boundaries to meet

program requirements. The document clarifies that states generally must implement management

measures for each source category identified in the EPA guidance developed under section

6217(g). The document also sets quantitative performance standards for some measures. Coastal

Nonpoint Pollution Control programs are not required to address sources that are clearly

regulated under the NPDES program as point source discharges. Specifically, such programs

would not need to address small municipal separate storm sewer systems and construction sites

covered under NPDES storm water permits (both general and individual). The guidance also

clarifies that regulatory and non-regulatory mechanisms may be used to meet the requirement for

enforceable policies and mechanisms, provided that non-regulatory approaches are backed by

enforceable state authority ensuring that the management measures will be implemented. Backup

authority may include sunset provisions for incentive programs. For example, a state may provide

additional incentives if too few owners or operators participate in a tax incentive program or

develop mandatory requirements to achieve the necessary implementation of management

measures.

3.4 Regional, State and Local Programs

In addition to the existing Federal storm water management programs, there are a variety

of State, local and regional storm water management programs in existence. Many of these
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programs pre-date the Federal programs and may include BMP design or performance standards,

site plan review and inspection programs, and technical assistance. A review of these programs is

outside the scope of this report.