## Contents

Introduction

................................................................................................ .................................................. 1 Section A. Numeric Post

- Construction Standards in MS4 Permits

............................................................... 3 Section B. Water Quality

- Based Effluent Limits in MS4 Permits

................................................................ 13 1. Listing of applicable TMDLS, WLAS, and the affected MS4s

........................................................... 14 2. Numeric limits and other quantifiable approaches for the specific pollutants of concern

............ 15 3. Required implementation of specific stormwater controls or management measures

................. 20 4. Other types of water quality

- based requirements

.......................................................................... 24 4.1 Permitting Authority Review and Approval of TMDL Plans

.................................................... 24 4.2 Monitoring/Modeling Requirements

...................................................................................... 29 4.3 TMDL

- Related Annual Reporting Requirements

..................................................................... 33 5. Requirements for discharges to impaired waters prior to TMDL approval

.................................... 35

i

# Introduction Although much progress has been made since the first stormwater regulations were promulgated in 1990, significant challenges remain in protecting water bodies from the impact of stormwater discharges

. Urban

- related stormwater has been identified as the source of impairment for tens of thousands of miles of rivers, streams, and coastal shorelines, as well as hundreds of thousands of acres of lakes, reservoirs and ponds in the United States. These impairments are largely due to the expansion of the built environment, which removes vegetation, alters the natural infiltr ation capability of the land , generates the discharge of pollutants , and leads to stream erosion

. National Pollutant Discharge Elimination System ( NPDES ) permitting authorities are employing a variety of different requirements in their municipal separate s torm sewer system (MS4) permits to combat these problems

. Permitting authorities have included numeric performance and/or design standards in MS4 permits to control discharges from new development and redevelopment. In addition, numeric effluent limitation s have been expressed as water quality

- based effluent limits (WQBELs) for specific pollutant parameters based on applicable wasteload allocations (WLAs) or other water quality objectives. Many permits also include requirements for the MS4 to implement spec ific management measures that are consistent with approved Total Maximum Daily Loads (TMDLs) or with the need to protect impaired waters prior to TMDL development. To develop this compendium, the U.S. Environmental Protection Agency ( EPA ) reviewed all stat e and EPA

- issued individual and general MS4 final permits issued up to June 2014

. The review focused on MS4 permitting approaches that incorporated retention

- based post

construction standards. It also focused on permitting approaches that directly implemen t TMDLs through numeric requirements or pollutant

- specific management measures , or a combination of both. MS4 permits were also reviewed to determine how permitting authorities measured progress of implementation of WQBEL requirements through such measures as review and approval of implementation plans, monitoring/modeling , and reporting MS4 Permit Universe
250 i ndividual MS4 permits cover approximately 855 Phase I MS4s

. 54 g eneral MS4 permits cover approximately 6,589 Phase II MS4s

. 100 i ndividual MS4 permits cover approximately 106 Phase II MS4s

. 3 watershed MS4 permits cover approximately 3 Phase I and 40 Phase II MS4s

. Regulated MS4s are typically cities, counties, towns , and villages; however, Phase II MS4s also include nontraditional MS4s such as public un iversities, departments of transportation, hospitals and prisons. The universe of the Phase II MS4 program changes every 10 years according to the U.S. Census Bureau definition of urbanized area.

1requirements. Finally, MS4 permit approaches were identified that dealt with discharges to impaired waters prior to TMDL approval. This compendium presents examples of different permitting approaches that EPA found in its nationwide review by describing , and in some cases excerpting , language from permits. The compendium is divided into two major sections

. Section A provides examples of permits that implement numeric post

- construction performance and/or design standards , and Section B presents different permitting approaches to address impaired waters and TMDLs

. Note that a number of the permits identified in the compendium are featured in more than one of the categories.
EPA notes that this compendium is intended to serve as a snapshot of permitting approaches. EPA anticipates that as permits are reissued in the coming months and year s, the information in this compendium will need to be updated to include new examples or modified information

. EPA has an interest in ensuring the accuracy of the information contained in this document, and therefore welcomes input on any aspect of this co mpendium at any time . T he Agency will update the compendium as needed based on the comments received

. EPA notes that the inclusion of any particular permit example should not be read as an Agency endorsement of the entire approach taken in that permit

. In addition , this document does not impose any new legally binding requirements on EPA, s tates , or the regulated community, and does not confer legal rights or impose legal obligations upon any member of the public. EPA made every attempt to ensure the accuracy of the examples included in this document ; however, in the event of a conflict between this compendium and any statute, regulation, or permit, the statute , regulation or permit controls. For more information about the NDPES Stormwater Program visit www.epa.gov/npdes/stormwater

. Parking island bioretention Stafford County, Virginia ( Credit: Abby Hall/EPA )

2

### Numeric Post

- Construction Standards 

## Section A



# Section A. Numeric Post

- Construction Standards in MS4 Permits
Many s tates have developed performance and/or design standards to control post

construction stormwater discharges from newly developed and redeveloped sites

. MS4 permits in 33 s tates have conditions implementing numeric performance standards. A comprehensive list of state standards for post

- con struction stormwater standards is provided at www.epa.gov/npdes/pubs/sw_st ate_summary_standards.pdf

. Many states have implemented numeric , retention

- based performance standard s for newly developed and redeveloped sites . These standards typically require or encourage using infiltration, evapo transpiration , or harvest practices to control a specified volume of storm water

. Volume retention is critical to reduce pollutant loads of a ll water quality parameters and to reduce erosion of the receiving waterbody . It also provide s multiple community benefits by treating stormwater as a resource

. R etention

- based performance standard s have been e xpressed in various ways. Some retention standards have been expressed as a volume of rainfall, a percentile storm event , or a ground water recharge volume that must be retained. The following permits are examples of MS4 permits that implement such standards (listed by EPA R egion ). Parking lot bioretention ( Credit: Abby Hall/EPA )



## REGI ON 1 Connecticut The 2013 Phase I City of Stamford, Connecticut, MS4 permit requires that the permittee incorporate the use of runoff reduction and low impact development (LID) practices into their land use regulations to meet a goal of maintaining post

- de velopment runoff conditions similar to pre

- development runoff conditions. Specifically, for all new development and redevelopment sites with a currently developed effective impervious cover of less than 40%,

3

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the applicant must design the site to retain the entire water quality volume for the site

. For redevelopment of sites with an effective impervious cover of 40% or more, a developer shall design the site to retain on

- site half the water quality volume for the site. In the 2004 Connecticut Stormwater Qual ity Manual , the recommended water quality volume is the runoff volume for 90 % of the average annual storm events, which is equivalent to the runoff associated with the first inch of rainfall. Any new Stamford MS4 discharge that is within 500 feet of the tid al wetland must discharge through a system designed to retain the volume of stormwater runoff generated by one inch of rainfall from the MS4 within the discharge's drainage area

. See Section 6.A.3.a.iii.

P ermit available upon request : Chris.Stone@ct.gov


## Vermont The 2012 Vermont general permit for discharges from small MS4s requires permit tees to implement and enforce the requirements in the 2002 Vermont Stormwater Management Manual for new development and redevelopment. The manual includes a ground water recharge volume standard that is determined as a function of annual pre

- development
re charge for a given soil group, average annual rainfall volume, and amount of impervious cover at a site. The ground water recharge standard can be met by one of two methods , or a combination of both. The first is designated as the percent volume method, and is based on infiltrating the recharge volume using one or more approved structural stormwater treatment practices. The second method is designated as the percent area method, and is based on draining runoff from some or all of the site impervious area through one or more approved nonstructural stormwater treatment practices. The manual also includes a water quality treatment standard that require s water quality treatment of 90% of annual storms based on removing total suspended solids ( TSS ) and total phosphorus (TP)

. The State of Vermont directly regulates post

- construction stormwater runoff from activities that result in creation of new or expansion of existing impervious surface of more than an acre; regardless of whether the site discharg es to an MS4 or directly to a waterbody. Consequently, the MS4 program must only regulate those sites that fall below the impervious cover threshold but disturb at least one acre of land or less if it is a part of a common plan of development. See Section IV.H.5.e.


## REGION 2 New Jersey The 2009 N ew Jersey general permit for discharges from small MS4s requires permittees to implement and enforce a program to address stormwater runoff from new development and redevelopment and adopt ordinances according to state stormwater management rule, N.J.A.C. 7:8

- 4, to control stormwater from nonresidential development and redevelopment projects. In

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addition, the permittee must ensure that any residential development and redevelopment projects that are subject to the Residential Site Improvement Standards for stormwater management (N.J.A.C. 5:21

- 7) comply with those standards

. The New Jersey standard for ground water recharge requires that 100% of the average annual pre

- construction ground water recharge volume for the site is maintained

. For the purpose of calculating runoff coefficients and ground water recharge, there is a presumption that the pre

- construction condition of a site or portion thereof is a wooded land use with good hydrologic condition. This ground water recharge requirement does not apply to previously developed portions of sites in urban redevelopment areas. The New Jersey standard for water quality provides that stormwater management measures are to be designed to reduce the post

- construction load of TSS in stormwater runoff generated from the water quality design storm by 80% of the anticipated load from the developed site, expressed as an annual average. See Part I.F.3.


## N ew York The 2010 New York general permit for discharges from small MS4s requires permittees to develop and implement a program to address stormwater runoff from new development and redevelopment that ensures projects meet applicable standards in the New York State Stormwater Management Design Ma nual

. The New York standard for new development requires runoff reduction be met by infiltration, ground water recharge, reuse, recycle, or evaporation of 100% of the post

- development water quality volume unless specific physical site limitations prohibit or limit the use of infiltration or ground water recharge

. This runoff reduction requirement is designed to replicate pre

- development hydrology by maintaining pre

construction infiltration, peak runoff flow, and discharge volume. The water quality volume i s calculated based on the amount of runoff equivalent to 90% rain event and the percent of impervious cover created at a site. This requirement can be accomplished by applying on - site green infrastructure techniques, standard stormwater management practices with runoff reduction capacity, and effective site planning. Redevelopment projects are encouraged to comply with the runoff reduction standard; however , it is not a requirement. Instead, alternative sizing criteria and stormwater management controls hav e been developed for redevelopment activities

. See Parts VII.A.5 and VIII.A.5

. 

## REGION 3 West Virginia The 2009 W est Virginia general permit for discharges from small MS4s requires permittees to implement and enforce site design standards for all new development and redevelopment disturbing one acre or more
. The site design standards require management measures that keep and mana ge on - site the first inch of rainfall from a 24

- hour storm preceded by 48 hours of no measurable precipitation

. This first inch of rainfall must be 100% managed with no discharge

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to surface waters, unless one of the two alternatives specified in the permit , off

- site mitigation and payment in lieu, are met

. See Part II.C.B.5.a.ii

. 

## Washington , DC The 2011 District of Columbia Phase I MS4 (DC MS4) p ermit requires the design, construction , and maintenance of stormwater controls to achieve on

- site retention of 1.2 inches of stormwater from a 24

- hour storm with a 72

- hour antecedent dry period through evapotranspiration, infiltration and/or storm water harvesting and use for new development and redevelopment projects greater than or equal to 5,000 square feet

. See Section 4. 1.1

. 

## Maryland Maryland has two general permits, one for municipalities and one for s tate and f ederal agencies , for discharges from small MS4s that require that stormwater management for new development and rede velopment be addressed for any proposed project that disturbs 5,000 square feet or more of earth. Because Maryland has a stormwater management program in place that regulates new development a nd redevelopment projects, the s tat e considers compliance with the s tate statute to be compliance with this minimum control measu re, this general permit, and federal regulations. Permittees shall comply with all s tate and local laws, regulations, ordinances, and procedures relating to storm water management. In addition , permittees must implement and comply with the principles, methods, and practices found in the 2000 Maryland Stormwater Design Manual , Volumes 1 and 2

. The manual specifies that environmental site d esign (ES D) shall be implemented to the maximum extent p racticable (MEP) to mimic pre

- development conditions. The standard for characterizing pre

- development runoff characteristics for new development projects is woods in good hydrologic condition. ESD practices are to be used to the MEP to meet the required water quality volume and the ground water recharge volume. The water quality volume is defined as the runoff volume from the 1

- inch rain event in the Maryland Eastern Rainfall Zone and 0.9 inch in the Maryland Western Rainf all Zone

. The manual includes a redevelopment policy that provides flexibility and alternative requirements for sites with more than 40% impervious area

. See Part III.E

. The Phase I MS4 permits in Ma ryland [ Anne Arundel County (201 4), Charles County (2002), Carroll County (2005), Frederick County (2002), Harford County (2004), Howard County (2005), Montgomery County (2010), Prince George’s County (2014), City of Baltimore (2013), and Baltimore County (2013) ] also require by reference that the permittee implement the stormwa ter management design policies, principles, methods, and practices found in the 2000 Maryland Stormwater Design Manual or other innovative stormwater management technolo gies approved by MDE

. See Part III. E.1

.

6

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## Section A

Delaware The 2013 New Castle County, Del a ware, MS4 permit requires permittees to implement a program to address stormwater from post

- development sites as prescribed under the Delaware Sediment and Storm water regulations

. In general, the Delaware Sediment and Stormwater regulations require stormwater controls sized according to the Resource Protection Event. The design parameter for the Resource Protection Event shall be the annualized runoff volume (RPv) produced by a storm having a 99% probability of occurring annually (i.e., the 1- year event) based on post

- developed conditions

. For new development, the RPv shall be reduced to an equivalent 0% effective imperviousness. For redevelopment, the RPv shall be reduced to an equivalent 70% of the existing effective imperviousness. The RPv shall be further reduced to an equivalent wooded condition for any existing meadow or wooded areas within the limit of disturbance based on the 2007 Delaware Land Use/Land Cove r data

. See Part II.A.4

. 

## REGION 4 Tennessee The 2010 Tennessee general permit for discharges from small MS4s requires for new development and redevelopment projects greater than or equal to one acre, management measures that are designed, built , and maintained to infiltrate, evapotranspire, harvest and/or use, at a minimum, the fir st inch of every rainfall event preceded by 72 hours of no measurable precipitation. This first inch of rainfall must be 100% managed with no stormwater runoff being discharged to surface waters

. See Section 4.2.5.2.1

. The 2011 Phase I City of Chattanooga, Tennessee, and the 2012 Phase I City of Nashville, T ennessee, MS4 permits include runoff reduct ion standards which require, in combination or alone, management measures that are designed, built , and maintained to infiltrate, evapotranspire, harvest , and/or use, at a minimum, the first inch of every rainfall event preceded by 72 hours of no measurabl e precipitation. The permittee may develop incentive standards for redevelopment and/or to increase use of green infrastructure best management practices ( BMPs ) while allowing flexibility for developers and designers to meet development standards. Such incentive standards are subject to certain criteria and may not exceed a maximum reduction of 50% of the required volume. For projects that cannot meet 100% of the runoff reduction requirement, the remainder must be treated prior to discharge with a technolog y documented to remove 80% TSS

. See Section 3.2.5.2

. 

## Kentucky The 2011 Phase I Louisville and Jefferson County, Kentucky, MS4 permit requires the development of an ordinance that requires water quality control measures to infiltrate,

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## Section A

evapo transpirate, harvest , and reuse at least the equivalent runoff produced from an 80 th percentile storm ( e.g. , 0.75 inches)

. See Part II.B.5

. 

## REGION 5 Minnesota The 2013 Minnesota general permit for discharges from small MS4s requires permittees to develop and implement a post

construction stormwater management program that requires new development projects to meet a standard of no net increase from pre

- project conditions of stormwater discharge volume, TSS , and TP . Redevelopment projec ts are required to meet a standard of a net reduction from pre

- project conditions of stormwater discharge volume, TSS , and TP

. See Part III.D.5

. Parking lot tree pit in Maplewood , Minnesota (Credit: Alisha Goldstein/EPA) 

## Wisconsin The 2014 Wisconsin general permit for discharges from small MS4s requires permittees to implement a program for new development and redevelopment that includes an ordinance or other regulatory mechanism that establishes post

construction performance standards equivalent to those contained in Wisconsin ’ s administrative c ode NR 151.122 through 151.126 , and 151.242 through 151.246. The infiltration performance standard in Wisconsin’s code is based on the imperviousness of the site. For example, sites with low imperviousness or development with less than 40% connected imperv iousness such as parks, cemeteries, and low

- density residential development, must infiltrate sufficient runoff volume so that the post

- development infiltration volume shall be at least 90% of the pre

- development infiltration volume, based on an average annual rainfall. For sites with 40 %– 80% connected 

### Wisconsin also has a numeric standard that applies to the entire MS4 not only to new development and redevelopment: The 2014 Wisconsin general permit for discharges from small MS4 requires permittees to meet at minimum a 20% reduction in the annual average mass of TSS d ischarging from the MS4 to surface waters of the state as compared to implementing no stormwater management controls. Source area controls, structural stormwater management practices, and nonstructural control practices implemented to achieve the 20% reduc tion in TSS shall be maintained. See Section 2.7.1

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imperviousness, such as medium - and high

- density residential, multi

- family development, industrial and institutional development, and office parks, the post

- development infiltration volume shall be at least 75 % of the pre

- development infiltration volume. For sites greater than 80% connected imperviousness , such as commercial strip malls, shopping centers, and commercial downtowns , the post

- development infiltration volume shall be at least 60% of the pre - develop ment infiltration volume

. See Section 2.5

. 

## REGION 6 New Mexico The 2012 Phase I MS4 permit for the City of Albuquerque, Albuquerque Metropolitan Arroyo Flood Control Authority (AMAFCA), New Mexico Department of Transportation (NMDOT), and University of New Mexico (UNM) requires the implementation and enforcement, via ordinance and/or other enforceable mechanism(s), of site design standards that capture the 90 th percentile storm event runoff to ensure the hydrology associated with new development and redevelopment sites mimic the pre

- development hydrology of the previously undeveloped site

. See Part I.C.5.b.


## REGION 8 Montana The 2009 M ontana general permit for discharges from small MS4s requires , for new development and redevelopment projects greater than or equal to one acre , the implementation of LID practices that infiltrate, evapotranspire, or capture for reuse the runoff generated from the first 0.5 inches of rainfall from a 24

- hour storm preceded by 48 hours of no measurable precipitation

. See Part II.B.5

. 

## REGION 9 California The 2013 C alifornia general permit for discharges from small MS4s requires that new development and redevelopment projects are designed to evapotranspire, infiltrate, harvest and use, and biotreat stormwater to meet at least one of the following hydraulic sizing design criteria: volumetric criteria (approximately the 85 th percentile 24

- hour storm runoff event or the volume of annual runoff required to achieve 80% or more captu re) or flow

- based criteria (the flow of runoff produced from a rain event equal to at least 0.2 inches per hour intensity; or the flow of runoff produced from a rain event equal to at least two times the 85 th percentile hourly rainfall intensity)

. See Sect ion E.12.e.ii.c

.

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## Section A
Los Angeles County , CA The 2012 Los Angeles County MS4 permit requires that each permittee shall require applicable
new develop ment and redevelopment projects to retain on

- site the stormwater quality design volume de fined as the runoff from: (1 ) t he 0.75

- inch, 24

- hour rain event or ( 2 ) the 85th percentile, 24

- hour rain event , whichever is greater

. When evaluating the potential for on

- site retention, each p ermittee shall consider the maximum potential for evapotranspiration from green roofs and rainfall harvest and use. Alternative compliance measures are allowed where meeting the standard is shown to be technically infeasible or where a project has been determined to provide an opportunity to replenish regional groundwater supplies at an off

- site location. Alternative compliance measures include on

- site biofiltration, off

- site infiltration, a propose d ground water replenish ment project, an off

- site retrofit project such as green streets, parking lot retrofits, green roofs, and rainfall harvest and use, or participate in a regional stormwater mitigation program. The permittee must also require applicab le new development and redevelopment projects within natural drainage systems to implement hydrologic control measures, to minimize changes in post

- development hydrologic stormwater runoff discharge rates, velocities, and duration. This shall be achieved b y maintaining the project’s pre

- project stormwater ru noff flow rates and durations

. See Part VI.D.7.c. 

## San Francisco , CA The 2009 San Francisco Bay Regiona l Water Board Municipal Permit requires permittee s to require applicable new development and redevelopment projects to treat 100% of the design storm runoff with LID treatment measures (harvesting and reuse, infiltration, evapotranspiration, or biotreatment) on - site or with LID treatment measures at an alternate stormwater treatment facility

. The design storm is defined to meet at least one of the following hydraulic sizing design criteria: (1) v olume hydraulic design b asis ( treat stormwater runo ff equal to approximately the 85 th percent ile 24

- hour storm runoff event or t he volume of annual runoff required to achieve 80 % or more capture ) ; (2) flow hydraulic design b asis ( treat (a) 10 % of the 50

- year peak flowrate; (b) t he flow of runoff produced b y a rain event equal to at least two times the 85 th percentile hourly rainfall intensity; or (c) t he flow of runoff resulting from a rain event equal to at least 0.2 inches per hour intensity ) ; or (3) combination flow and volume design b asis ( treat at leas t 80 % of the total runoff over the life of the project)

. See Sections C.3.c and C.3.d

. 

## San Diego , CA The 2013 San Diego Regional MS4 p ermit requires the permittee to require applicable new development and redev elopment projects to implement LID BMPs that are designed to retain (i.e. intercept, store, infiltrate, evaporate, and evapotranspire) on

- site the pollutants contained

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## Section A

in the volume of stormwater runoff produced from a 24

- hour , 85 th percentile storm event (design capture volume) , with the potential to implement off

- site alternative compliance projects that will have a greater overall water quality benefit for the watershed than if the project were to implement structural BMPs on

- site . In addition, the permittee must require implementation of on

- site BMPs to manage hydromodification that may be caused by stormwater runoff discharged from a project as follows: (1 ) post

- project runoff conditions (flow rates and durations) must not exceed pre

- development runoff conditions by more than 10 % (for the range of flows that result in increased potential for erosion, or degraded instream habitat downstream of the project ) ; and (2 ) avoid critical sediment yield areas, or implement measures that allow critical coarse sediment to be discharged to receiving waters, such that there is no net impact to the receiving water

. See Part II.E.3.c

. 

## REGION 10 Anchorage, AK The 2010 Anchorage, Ala ska, individual MS4 permit require s that for new development and redevelopment projects that result in a land disturbance of 10,000 square feet or more, management measures that keep and manage the runoff generated from the first 0.52 inches of rainfall fr om a 24

- hour event preceded by 48 hours of no measureable precipitation. The ordinance or regulatory mechanism must require that the first 0.52 inches of rainfall be 100% managed with no discharge to surface waters, except in circumstances described in the permit. Runoff volume reduction can be achieved by canopy interception, soil amendments, evapotranspiration, rainfall harvesting, engineered infiltration, extended filtration, and/or any combination of su ch practices

. See Part II.B.2

. 

## Washington The 2013 Western Washington general permit for discharges from small MS4s and the 2013 Washington Phase I MS4 permit require permittee s to implement LID performance standard s for certain newly developed and redeveloped sites. The standard requires that stormwater discharges match developed discharge durations to pre

- developed durations for the range of pre - developed discharge rates from 8% of the 2

- year f low to 50% of the 2

- year flow

. See Appendix I, Section 4.5

. 

## Oregon The 2011 Phase I Portland, Oregon, MS4 permit requires new develo pment and redevelopment projects that create or replace 500 square feet of impervious surface to capture and treat 80% of the annual average runoff volume, based on a documented local or regional rainfall

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### Numeric Post

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## Section A

frequency and intensity. The program must prioritiz e and include LID , green infrastructure , or equivalent design and construction approaches

. See Schedule A.4.f

. The 2010 Phase I Salem , 2010 Phase I Gresham/Fairview, 2010 Phase I Multnomah, 2011 Phase 1 Eugene, and the 2012 Phase I Clackamas County, Oregon, MS4 permits have the same standard , but it applies to new development and redevelopment projects of varying site size thresholds.

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## Section B



# Section B. Water Quality

- Based Efflu ent Limits in MS4 Permits
This section presents examples of different types of permit requirements that are based on TMDLs or concern for impaired waters

. The permits EPA reviewed showed that permitting authorities are taking a variety of different approaches to establishing WQBELs in their MS4 permits

. Although s ome water quality

- based requirements in these permits are in the form of numeric effluent limits, others are expressed as specific control measures that must be implemented to b e consistent with applicable water quality standards or WLAs. Permeable pavement and bioretention in Albuquerque, New Mexico (Photo courtesy of AridLID.org) Overall, EPA fou nd that nearly all MS4 permits include at least some language addressing impaired waters

. For the purposes of presenting the different types of permitting approaches found in EPA’s survey, this compendium organize s the examples into the following categorie s:
1. Listing of applicable TMDLs, WLAs, and/or the affected MS4s 2. Numeric effluent limits and other quantifiable approaches for the specific pollutants of
concern 1 3. Required implement ation of specific stormwater controls or management measures 4. Other types of water quality

- based requirements

a. Permitting Authority Review and Approval of TMDL Plans b. Monitoring/Modeling Requirements

c. TMDL

- Related Annual Reporting Requirements 5. Requirements for discharges to impaired waters prior to TMDL approval

1 The use of the term pollutant of concern in this compendium refers to the pollutant parameter(s) for which a waterbody is listed as impaired under section 303(d) of the Clean Water Act or for which a TMDL has been approved or established by EPA.

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### Water Quality

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## Section B

**1. L**  **isting of applicable TMDLS, WLAS, and the affected MS4s** A first step in determining whether additional permit requirements are necessary as a result of an approved or established TMDL is to establish whether any TMDLs or WLAs apply to the MS4s being permit ted

. Although many permits have placed the responsibility for making this determination on the MS4 permittee, several permits have instead included information on
w hich TMDLs and WLAs apply and which MS4s are affected directly in the permit

. This approach reduces the amount of work required of the permittee in interpreting TMDL documents, and provides greater clarity for the permittee in understanding what water quality

related requirements may apply. The following are examples of this approach

. 

## General Per mits California The 20 13 California small MS4 permit includes tables showing applicable TMDLs, the MS4s covered by WLAs, the applicable WLA, and individualized TMDL implementation req uirements for each affected MS4. See Attachment G

. 

## Minnesota The Minnesota Pollution Contr ol Agency includes on its website the Master List MS4 Permit TMDLs Spreadsheet that identifies TMDLs and associated WLAs that apply to its regulated MS4s. See the Permit tab. 

## Washington The 201 3 Western Washington small MS4 permit identif ies each TMDL within the perm it area and all affected MS4 permittees

. See Appendix 2

. The permit also states that “For applicable TMDLs not listed in Appendix 2, compliance with this Permit shall constitute compliance wit h the TMDL.” See Section S7.B. 

## Individual Permits Anchorage, AK The 2010 Anchorage, Alaska, MS4 permit fact sheet includes a list of completed TMDLs that identifies the pollutants of concern and percent reduction needed

. Contact state for permit.

14

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## Section B
Menomonee Watershed, Wisconsin The 2012 Menomonee Watershed Permit for Milwaukee, Wisconsin, and 10 other MS4 permittees includes a table that lists all of the impaired waterbodie s in the Menomonee River Watershed, the pollutants of concern, and the contributing MS4

. See Table 1

. 

## Prince George’s County, MD The 2014 Prince George’s County, M aryland, MS4 permit provides an attachment, which includes a three

- page list of EPA

- approved TMDLs in the County

. See Attachment B

. 

## 2. **Numeric limits and other quantifiable approaches for the**  **specific pollutants of concern** NPDES permits for MS4 discharges have included numeric effluent limitations for specific parameters based on an applicable TMDL WLA

. Some examples of MS4 permits with numeric effluent limitations and other quantifiable approaches include the following

. 

## General Permits California The 2013 California general permi t for discharges fr om s mall MS4s incorporates numeric WLAs that apply to individual small MS4s

. Although the permit states that these numeric WLAs (for fecal coliform, sediment, and pesticides) apply to the named MS4s, it provides near

- term actions, in the form of specific m anagement measures, which constitute the bulk of what the permittee must do to be consistent with the WLAs

. For example, for the Pajaro River TMDL and Implementation Plan for sediment, four MS4 permittees are prohibited from discharging sediment to the lis ted waterbodies in excess of the incorporated WLAs (Table 1). The allocations represent a 90% reduction in sediment loading to e ach waterbody from urban roads. See Attachment G – Region Specific Requirements, Regional Water Board Approved TMDLs

— where urban runoff is listed as a source. Table 1. Pajaro R iver TMDL for Sediment
Applicable MS4s Major Subwatershed Metric Tons of Sediment Per Year City of Morgan Hill City of Gilroy City of Hollister City of Watsonville Tres Pinos 1 San Benito 100 Llagas 787 Uvas 139 Upper Pajaro 161 Corralitos 284 Mount of Pajaro River 191

15

### Water Quality

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## Section B
Virginia The 2013 Virginia general permit for discharges from small MS4s requires permittees discharging to the Chesapeake Bay watershed to reduce loadings of nitrogen, phosphorus , and TSS from existing developed lands (pre

- June 30, 2009) by 5 % of its modeled share by the permit expiration date

. The permit also requires a 5 % offset of increased loads from new and grandfathered construction projects disturbing one or more acres for which an average land cover condition greater than 16 % impervious cover was used in the design of post

- development stormwater facilities

. The general permit includes tables with loading rates to be used by the permittee to calculate required load reductions from existing sources. Load reductions are to be accomplished through the implementation of a Chesapeake Bay TMDL Action Plan that outli nes the means and methods by which the permittee will achieve the required reductions. For this permit term, the permit states that compliance with these requirements “represents adequate progress for this state permit term towards achieving TMDL WLAs cons istent with the assumptions and requirements of the TMDL.” See Sections I.C, I.C.2.a.5, Tables 3.a –3 .d, I.C.2.a.7 and 8, and I.C.3 . In the Watershed Implementation Plan for the Chesapeake Bay TMDL, Virginia committed to a phased approach to reducing nitrogen, phosphorus, and TSS from the MS4 and will include additional loading reductions in the next two permits terms. 

## Individual Permits Arlington County, VA
The 2013 Arlington County, Virginia, MS4 permit has the same pollutant reduction requirements for nitrogen, phosphorus , and TSS as the 2013 Virginia s mall MS4 g eneral p ermit (described above). The Arlington County MS4 permit also requires the permittee to identify and submit to the state at least seven retrofit projects within its watershed retrofit plans that will be implemented within County rights

- of

- way or on County property within 60 months of permit issuance

. The MS4 is also required to:

• Plant a min imum of 2,000 trees on County lands and develop a program to distribute a minimum of 2,000 trees to private property owners.

• Have funding to accommodate a minimum of 200 participants in the StormwaterWise Landscape program , which provides cost

- sharing and technical assistance for the installation of small

- scale BMPs to reduce stormwater runoff from private properties.
See Parts I.B.2.c and I.D.1.b

.

16

### Water Quality

- Based Effluent Limitations 

## Section B

California Permits Lake Tahoe, CA The 2011 Lake Tahoe, California, MS4 permit , covering the City of South Lake Tahoe, and portions of El Dorado County and Placer County in the Lake Tahoe Hydrologic Unit, requires each permittee to reduce fine sediment particle (FSP), TP and total nitrogen (TN) loads by 10%, 7%, and 8%, respectively, by September 30, 2016

. These percentage reduction requirements were applied to each of the permittee’s baseline load of FSP, TP, and TN to determine the maximum load allowance for each permittee to meet the 5

- year load reduction requirements

. See Section IV.B and Table IV.B.1. 

## Los Angeles Count y, CA The 2012 Los Angeles County, California, systemwide permit requires permittees to comply with numeric WQBELs based on WLAs in approved TMDLs

. The permit includes comprehensive provisions to achieve WLAs from applicable TMDLs, including interim and final WQBELs and corresponding compliance schedules consistent with the state

- adopted TMDL I mplementation P lan, compliance monitoring, and reporting requirements, and for each pollutant of concern

. For example, Attachment L of the permit prescribes final and interim WQBELs that apply to MS4s discharging to the Santa Clara River . T he attachment includes WQBELs for nitrogen, chloride, trash, and E. coli that are consistent with the WLAs from approved TMDLs for the Santa Clara River watershed

. For the interim WQBELs, the permit includes several alternatives from which the permittees can choose to demonstrate compliance

. A permit can demonstrate compliance with the applicable interim WQBEL in any of the follo wing ways:

• There are no violations of the interim WQBEL for the pollutant of concern at the permittee’s applicable MS4 outfalls;

• There are no exceedances of the applicable receiving water limitation for the pollutant of concern in the receiving water at or downstream of the permittee’s outfalls;

• There is no direct or indirect discharge from the permittee’s MS4 to the receiving water subject to the interim WQBEL and/or the receiving water limitation for the pollutant of concern;

• The permittee has submitted a nd is fully implementing an approved Watershed Management Program (WMP) or an Enhanced Watershed Management Program (EWMP) , which requires among other things that the permittee include multi

- benefit regional projects that retain through infiltration or cap ture and reuse the stormwater

17

### Water Quality

- Based Effluent Limitations 

## Section B

volume from the 85 th percentile, 24

- hour storm for the drainage areas tributary to these projects. See Parts VI.C and E, and Attachments L – R. 

## Orange County, CA The 2009 Orange County, California, MS4 permit establishes a number of different numeric WQBELs that affect MS4s discharging to certain watersheds

. For instance, for MS4s discharging to the Newport Watershed, the permit requires compliance with WLAs for metals (cadmium, copper, lead, zinc, mercury, and chromium), organochlorine compounds, and selenium

. See Section XVIII.B.4

. Not e that the original TMDLs for these constituents included no implementation plans or compliance schedules for attainment . During development of the modified TMDL , which will include an implementation plan, the permittees are required to continue working to wards meeting the WLAs

. In addition , for TMDLs with implementation plans, the permit includes WLAs that are required to be met as soon as 2013 (e.g., recreational standards for fecal coliform), but by no later than 2019 (e.g., shellfish standards for fecal coliform)

. See Section XVIII.C

. Other numeric WLAs are required in Section XVIII.D for diazinon, chloropyrifos, TN , TP , and sediment

. Note that, according to the permitting authority, the WLAs for these constituents have already been achieved

. Compliance with the WLAs is to be determined by receiving water monitoring . W here monitoring reveals that the WLAs are exceeded, the permittees are required to evaluate and submit to the permitting authority within 12 months of the exceedances a proposal for implementing additional BMPs

. See Section XVIII.E. 

## San Diego, CA The 2013 San Diego Regional MS4 permit contain s numeric effluent limitations for diazinon, dissolved copper, TN , TP , lead, zinc, and indicator bacteria, which are consistent with applicable TMDL WLAs

. The permit identifies for each applicable TMDL information about the TMDL (waterbodies, adoption dates ); which MS4 co

- permittees are affected ; final compliance requirements (final compliance dates, receiving water and/or effluent limitations, BMP requirements, and final TMDL compliance determination ); interim compliance requirements ; and specific monitoring and assessment requirements

. See Attachment E. 

## San Francisco, CA The 2009 San Francisco Bay Regional MS4 permit requires the permittee to implement trash load reduction plans and actions to reduce trash loads from their MS4 by 40% by 2014, 70% by 2017 , and 100% by 2022.

18

### Water Quality

- Based Effluent Limitations 

## Section B
Prince George’s County, MD The 2014 Prince George’s County, Maryland, MS4 permit requires the County to develop a work plan within one year to address the Anacostia Trash TMDL, which estimates that 170,628 pounds of trash will need to be removed annually

. The work plan must include a detailed schedule, trash reduction benchmarks in years two and four, and methods of implementation. The County must also develop accounting methods to quantify annual trash reductions

. The permit also requires restoration plans for waters with approved TMDLs

. The restoration plans must address the stormwater WLA for all EPA

- approved TMDLs in the County. An annual TMDL assessment report is required to be submitted to the permitting authority

. In addition , the permit requires the County, within the 5- year permit term, to achieve reductions in discharges consistent with the Chesapeake Bay TMDL by restoring 20 % of the previously developed impervious land with little or no controls

. See similar requirements in the 2014 Anne Arundel County, Maryland, MS4 permit (Parts IV.E.2.a and VI.A).

Note t hat Maryland has five other Phase I MS4 permits [ Charles County (2002), Carroll County (2005), Frederick County (2002), Harford County (2004), and Howard County (2005) ] that are required during their current administratively extended permit term to restore 10% of the County’s impervious surface area that was identified during the previous permit term. These permits also require permittees to begin to implement an additional 10% restoration during the permit term for a total goal of 20% restoration. The perm it further requires monitoring to determine the effectiveness of the restoration efforts toward achieving water quality. See Parts IV.D.4, IV.E, and VI.A

. See similar requirements in Parts IV.E and VI of both the 2013 Baltimore County, Maryland, MS4 permit and the 2013 Baltimore City, Maryland, MS4 permit

. 

## Honolulu, HI The 2011 Honolulu City/County MS4 permit requires compliance with the “urban source wasteload allocation” based on different TMDLs in table format including applicable allocations ; existing loads ; and reductions needed for TN , TP , and TSS

. See Sections F.3.b and F.3.b.1 thr ough F.3.b.6. 

## Washington, DC
The 2011 DC MS4 permit requires the permittee to remove 103,188 pounds of trash annually

. Reductions must be made through a combination of the following approaches:

• Direct removal from waterbodies ( e.g., stream cleanups, skimmers )

• Direct removal from the MS4 ( e.g., catch basin cleanout, trash racks )

19

### Water Quality

- Based Effluent Limitations 

## Section B

• Direct removal prior to entry to the MS4 ( e.g., street sweeping )

• Prevention throug h additional disposal alternatives ( e.g., public trash/recycling collection )

• Prevention through waste reduction practices, regulations , and/or incentives ( e.g., bag fees )
The MS4 is also required to achieve the following numeric requirements:

• Implement retrofits for stormwater discharges from a minimum of 18,000,000 square feet of impervious surfaces during the permit term. A minimum of 1,500,000 square feet of this objective must be in transportation rights

- of

- way;

• Achieve a minimum net annual tree plan ting rate of 4,150 plantings annually within the DC MS4 area, with the objective of a D istrict

- wide urban tree canopy coverage of 40% by 2035. The annual total tree planting shall be calculated as a net increase, such that annual mortality is also included in the estimate. Trees must be planted in accordance with the Planting Specifications issued by the International Society of Arboriculture as appropriate to the site conditions; and

• Install at a minimum 350,000 square feet of green roofs on District prope rties during the term of the permit (including schools and school administration buildings).

See Sections 4.1.5.4, 4.1.6.2, 4.1.7.2, and 4.10.1

. 

## 3. **Required implement**  **ation of specific stormwater controls or**  **management measures** EPA found several examples of permits that require their MS4 permittees to implement specific BMPs or other management measures to ensure consistency with the applicable TMDLs

. This approach provides both the permitting authority and the permittee with measurable performance measures that can be readily tracked, and it provides both parties with the ability to understand what actions constitute reasonable further progress towards achieving the TMDL and protecting water quality. 

## General Permits California Th e 2013 C alifornia g eneral permi t for d ischarges from small MS4s includes a dditional (narrative) s tormwater c ontrol r equirements that a re deeme d by t he pe rmitting a uthority to be consistent with applicable T MDLs

. These requirements are individualized for e ach pollu tant of concern, and d ifferent r equireme nts ap ply to e ach imp aired w atershe d an d c ontributing MS4

20

### Water Quality

- Based Effluent Limitations 

## Section B

dischargers

. For instance, to be consistent with the Napa River pathogens WLA for municipal stormwater, the permit requires the six affected MS4s to educate the public about pathogen impacts and ways to reduce pathogen discharges, and to develop and implement programs to reduce/eliminate fecal coliform loading fr om pet was tes, among other requirements. See Attachment G.


## Minnesota The 2013 Minnesota general permit for discharges from small MS4s requires each regulated small MS4 to submit a compliance schedule with their permit application showing what BMPs will be implemented and when during the permit term to address applicable WLAs, and target dates for when the WLAs will be achieved

. Note that the state provides public notice and an opportunity to comment on each permit application

. See Section II.D.6.f. 

## Pennsylvania The 2013 Pennsylvania general perm it for discharges from small MS4s requires that permittees develop, submit for approval , and ensure implementation of an MS4 TMDL Plan that is designed to achieve pollutant reductions requirements of the applicable WLAs

. The permit provides permittees with a list of nine alternative TMDL Control Measures for permittees to consider for reducing pollutants consistent with applicable WLAs

. See Section II.F.1 (NOI Instructions). 

## Washington The 2013 Western Washington Phase II Municipal Stormwater Permit includes tables that establish additional watershed

- specific actions that are required of each named MS4

. The actions are differentiated based on the applicable TMDL and pollutant of
concern
. See Appendix 2.

Street - side swale and pervious concrete sidewalk in Seattle, Washington

(Credit: Abby Hall/EPA) The 2014 Washington State Department of Transportation (WDOT) MS4 permit includes specific mandated action items for WDOT that are associated with individual TMDLs

. For example, to implement the Hangman Creek Fecal Coliform, Temperature, TSS/Turbidity TMDL , WDOT is required to take the following actions by deadlines specified in the permit:

21

### Water Quality

- Based Effluent Limitations 

## Section B

• Within WDOT’s right

- of

- way inside the TMDL boundary, identify illicit sources of bacteria and sediment disch arges to the stormwater conveyance system

. A priority list of stream crossings and stormwater discharge locations to Hangman Creek are identified;

• If stormwater discharges that transport bacteria over natural background levels to listed receiving waters ar e found from sources within WSDOT’s right

- of

- way and control, WSDOT will apply BMPs from their Stormwater Management Program Plan ( SWMPP ) or perform remediation to correct bacteria discharges;

• To address TSS and turbidity, WSDOT will work to prevent sediment from entering area waterways along SR 27 (in upper watershed) and SR 195 right s- of

- way
. WSDOT will prioritize problem areas and work with individual property owners to prevent sediment from entering area waterways via WSDOT’s MS4; and

• Evaluate whether s tormwater discharges contribute to elevated temperature issued, and, if so, take steps to reduce the adverse thermal stormwater discharge impacts to Hangman Creek or its tributaries. See Appendix 3 (Applicable TMDL Requirements). 

## Individual Permits Denver, CO The 2009 Denver, Colorado, MS4 permit identifies specific requirements that apply to discharges to Segment 14 of the Upper South Platte River Basin associated with WLAs from the approved E. coli TMDL

. The permit requires the permittee to identify outfa lls with dry weather flows and to identify outfalls of concern ; to monitor priority outfalls of concern for flow rates and E. coli densities ; to implement a system maintenance program for listed priority basins (which includes storm sewer cleaning and sanitary sewer investigations ); to install markers at least 90 % of storm drain inlets in areas with public access ; and to conduct a public outreach program focused on sources that contribute E. coli loads to the MS4

. See Part I.B.1.f. The permit also requires the permittee to develop and implement new programs and BMPs, in addition to the activities described above, to reduce dry weather discharges of E. coli to the extent necessary so that by the end of the compliance period , dry weather discharges from MS4 ou tfalls of concern do not contribute to an exceedance of the E. coli standard (do not exceed an E. coli density of 126 cfu per 100 m l for a geometric mean of all samples collected at a specific outfall in a 30

- day period)

. The permit includes a compliance s chedule for meeting this requirement by November 30, 2018

. See Part I.B.1.f. Contact state for permit.

22

### Water Quality

- Based Effluent Limitations 

## Section B

Florida Phase I MS4 Permits Florida’s Phase I MS4 permits require permittees that discharge to waterbodies with an approved TMDL and a Basin Management Action Plan (BMAP) to comply with the provisions of the BMAP and report on the status of BMAP implementation with each annual report . For waterbodies with an approved TMDL, but no BMAP, the MS4 permittee is required to submit for review and approval a TMDL prioritization schedule within 6 months of the permit effective date. At a minimum, the highest priority TMDL is to have a plan to address the pollutant of concern by the end of the permit cycle. See, for example, Parts VIII. B.2 and B.3.a of the Pinellas and Miami

- Dade permits. Florida’s permits also include specific requirements for fecal coliform TMDL waters that do not have a BMAP

. In these cases, the MS4 permittee is required to develop and submit a bacterial pollution control plan with specific elemen ts such as bacteria source tracking and a pet waste management program. The bacteria pollution control plan is to be implemented in accordance to the schedule within the approved plan. The permittees are required to submit a status report with each a nnual r eport. See, for example, Part VIII.B.4 of the Pinellas and Miami

- Dad permits. Contact state for permits. 

## San Francisco, CA
The 2009 San Francisco Bay Regional Stormwater MS4 Permit includes narrative and numeric WQBELs for trash, mercury, polychlorinated biphenyls , pesticides, copper, polybrominated diphenyl ether , and selenium

. The permit requires interim milestones and pollutant

- specific control measu res that are consistent with the implementation actions identified in the applicable WLA . (F or “urban stormwater , ” see pages 15

– 16 of the Basin Plan Amendments to the San Francisco Basin Water Quality Control Plan, www.swrcb.ca.gov/sanfranciscobay/water_issues/programs/TMDLs/sfbaymercury/Adopted_B PA_080906.pdf .) For example, the San Francisco Basin Water Quality Control Plan for mercury in cludes interim and final milestones of 120 kilograms per year ( kg/yr ) loading by February 2018 and 82 kg/yr by February 2028

. The permit incorporates both the aggregate WLA and the interim loading milestone, as well as implementation requirements that are identified in the TMDL Implementation Plan, including requirements to: (1) Implement a mercury source control program ; (2) Implement a monitoring system to quantify mercury loads and loads reduced ; (3) Monitor methylmercury in discharges ;

23

### Water Quality

- Based Effluent Limitations 

## Section B

(4) Conduct a fat e and transport study ; and (5) Develop an allocation sharing mechanism.

See Sections C

- 9 through C- 14.


## 4. **Other t**  **ypes of**  **w ater**  **q uality**  **-b ased**  **r equirements**  A number of permits exhibit alternative means of ensuring consistency with applicable TMDLs, other than by adopting numeric requirements or implementing specific stormwater controls

. The following permitting approaches are illustrative of these types of requirements

. 

### 4.1 **Permitting Authority Review and Approval of TMDL Plans** Several permitting authoriti es require that their permittees develop a TMDL P lan (or the TMDL component of the overall stormwater management program [ SWMP ] document) and submit it for review and/or approval

. The benefit of this type of approach is that through the permitting authorit y review there is an additional level of assurance that the proposed plan will be consistent with the assumptions and requirements of any available WLA in an approved TMDL. 

## General Permits Vermont The 2012 Vermont general permit for discharges from small MS4s requires permittees that discharge to a stormwater

- impaired water with an approved TMDL to submit , within 3 years of the permit issuance date , a Flow Restoration Plan for state review and approval. 

## Pennsylvania The 2013 Pennsylvania general permit for discharges fr om small MS4s requires permittees discharging to impaired waters for which a TMDL has been approved to submit with their notice of intent ( NOI ) for review and approval by the permitting authority an MS4 TMDL Plan designed to achieve pollutant reductions co nsistent with the applicable WLA

. The permit requires that
[P] ermittees must include the reductions in pollutant loads attained by implementation of control measures or BMPs, broken down measure by measure or BMP by BMP. Permittees must have physical pollu tant removal measures installed on

- the

- ground in time for their successful operation to be documented in the periodic report or the progress report submitted at the end of the third year of coverage under this permit. Additional measurable substantial progress with installation of physical pollutant removal measures must be documented in the reports submitted with the next successive renewal NOI or application for a renewal permit.

24

### Water Quality

- Based Effluent Limitations 

## Section B

A further description of these reports is found in the NOI Instructions. Th e permit also requires that MS4 TMDL Plans and Designs be signed and sealed by a professional engineer holding a valid license in good standing from the state. See Section II.F (NOI Instructions) and Part C.1 (Authorization to Discharge). 

## Virginia The 2013 Virginia general permit for discharges from small MS4s requires that permittees discharging to the Chesapeake Bay watershed submit a Chesapeake Bay TMDL Action Plan within 24 months of the permit effective date for review and approval by the permitting authority

. Unless specifically denied in writing by the department, TMDL Action Plans and updates developed in accordance with this section of the permit become effective and enforceable 90 days after the date received by the department . The Chesapeake Bay TMDL Action Plans must include the following :

• A review of the current MS4 program to identify new or modified legal authorities to meet these requirements;

• An estimate of th e annual pollutant of concern loads discharged from the existing sources based loading rates specified in the permit;

• A determination of the total pollutant load reductions necessary to reduce the annual pollutant of concern loads from existing sources;

• Th e management practices and retrofit programs that will be utilized to meet the required load reductions and a schedule to achieve those reductions

. The schedule should include annual benchmarks to demonstrate the ongoing progress in meeting the reductions; and

• The means and methods to offset the increased loads from new sources that disturb one or more acres as a result of the utilization of an average land cover condition greater than 16 % impervious cover for the design of post

- development stormwater manag ement facilities

. The permittee must use tables in the permit to develop the equivalent pollutant load for nitrogen and TSS

. T he permittee must offset 5 % of the calculated increased load from these new sources during the permit cycle.
See Table 1 and Secti on I.C.2

.

25

### Water Quality

- Based Effluent Limitations 

## Section B
Georgia
The 2012 Georgia general permit for discharges from small MS4s requires existing permittees discharging to impaired waters with an approved TMDL to develop and submit for review and approval to the permitting authority an Impaired Waters Plan (for MS4s with a population of < 10,000) or a Monitoring and Implementation Plan (for MS4s with a population of > 10,000)

.

• The Impaired Waters Plan, which must be submitted by a specific date, must include a list of the impaired waters and the pollutant(s) of concern, a map showing the locations of the impaired waters and all MS4 outfalls discharging to those waters, BMP s that will be implemented to address each pollutant of concern, and a schedule for implementing the BMPs

.

• The Monitoring and Implementation Plan, which also must be submitted by a specified date, must identify where wet weather monitoring will occur, samp le type, frequency, schedule to begin monitoring, and a description of the BMPs that will be implemented to address each pollutant of concern.
See Sections 4.4.1 and 4.4.2

. 

## Minnesota
The 2013 Minnesota general permit for discharges from small MS4s requires each applicant to submit its Stormwater Pollution Prevention Program ( SWPPP ) document to the permitting
a uthority, including a compliance schedule for addressing applicable WLAs with the following required elements:

• Interim milestones, expressed as BMP s or progress toward implementation of BMP s to be achieved during the term of this permit

• Dates for implementation of interim milestones

• Strategies for continued BMP implementation beyond the term of this permit

• Target dates the applicable WLA (s) will be achieved
See Sections II.D.6 and III.E. 

## California The 2013 California general permit for discharges from small MS4s requires some of its permittees, for specific TMDLs, to submit for review and approval a plan to minimize, control, and preferably prevent the discharge of the pollutant of concern.

26

### Water Quality

- Based Effluent Limitations 

## Section B

Individual Permits Arlington Country, VA The 2013 Arlington County, Virginia, MS4 permit has the same requirement as the 2013 Virginia
s mall MS4 g eneral p ermit to submit a Chesapeake Bay TMDL Action Plan within 24 months of the permit effective date for review and approval by the permitting authority (described above). See Part I.D.1.b. 

## Denver, CO The 2009 Denver, Colorado, MS4 permit identifies specific requirements that apply to discharges to Segment 14 of the Upper South Platte River b asin associated with WLAs from the approved E. coli TMDL

. The permit requires the permittee to submit to the state an E. coli control plan, which, among other things, must include requirements for the permittee to identify outfalls with dry weather flows and to identify outfalls of concern ; to monitor priority outfalls of concern for flow rates and E. coli densities ; to implement a system maintenance program for listed “priority basins” (which includes storm sewer cleaning and sanitary sewer investigations ); to install markers for at least 90 % of storm drain inlets in areas with public
access ; to conduct a public outreach program focused on sources that contribute E. coli loads to the MS4 ; and to develop and implement additional programs and BMPs as necessary to ensure that dry weather discharges from MS4 outfalls of concern by November 30, 2018 , do not cont ribute to an exceedance of the E. coli standard (do not exceed an E. coli density of 126 cfu per 100 ml for a geometric mean of all samples collected at a specific outfall in a 30

- day period)

. See Part I.B.1.f. Contact state for permit. 

## Los Angeles Country, CA The 2012 Los Angeles County, C alifornia, systemwide permit provides permittees with the option of demonstrating compliance with interim WQBELs by implementing a state

- approved WMP or EWMP

. The permit specifies what each WMP or EWMP must include to be approvable

. For example, each EWMP must, among other things:

• Prioritize water quality issues resulting from stormwater/non

- stormwater discharges to the receiving water within each Watershed Management Area ;

• Identify and implement strategies, control measures, and BMPs to ensure that discharges ( 1 ) achieve applicable WQBELs; ( 2 ) do not cause or contribute to exceedances of receiving water limitations; and ( 3 ) do not include non

- stormwater discharges that are prohibited;

27

### Water Quality

- Based Effluent Limitations 

## Section B

• Execute an integrated monitoring program to determine progress towards achieving applicable limitations and/or action levels;

• Modify strategies, control measures, and BMPs as necessary based on analysis of monitoring data to ensure applicable WQBELs and receiving water limitations and other milestones are achieved in the required timeframes;

• Include multi

- benefit regional project s to ensure that MS4 discharges achieve compliance with all final WQBELs and do not cause or contribute to exceedances of receiving water limitations by retaining through infiltration or capture and reuse the stormwater volume of the 8 5 th percentile, 24

- ho ur storm for the drainage areas tributary to the multi

- benefit regional projects; and

• Maximize the effectiveness of funds through analysis of alternatives and section and sequencing of actions needed to address human health and water quality

- related challe nges and noncompliance. The permittee is considered in compliance with the interim WQBELs if it:

• Provides timely notice of its intent to develop a WMP or EWMP;

• Meets all deadlines for development of the WMP or EWMP;

• For the area covered by the program, tar gets implementation of watershed control measures in its existing SWMP to address known contributions of pollutants from MS4 discharges that cause or contribute to exceedances of receiving water limitations;

• Demonstrates reasonable assurance (through a pee r- reviewed quantitative modeling approach) that implementation of the actions/projects proposed in the WMP or EWMP will achieve WQBELs and receiving water limitations by required deadlines;

• Receives final approval of the WMP or EWMP ;

• Fully implements its approved WMP or EWMP, including all proposed actions/projects, per the approved time schedules; and

• Periodically adapts its WMP or EWMP, when necessary, if monitoring data indicate that expected water quality outcomes are not being achieved

. See Parts V I.C and E , a nd A ttachments L

– R. 

## Montgomery C ounty, MD Th e 2010 Montgomery C ounty, Maryland, MS4 p ermit r equires the permittee t o submi t to t he st a te for re view a nd ap proval a plan f or each E PA -a pproved TMDL for th e portion of a

28

### Water Quality

- Based Effluent Limitations 

## Section B

watershed covered by the permit

. The plans must include the actions and deadlines to meet the required pollutant load reduction benc hmarks and WLAs within the specified timeframe

. See Part III.J.2

. 

## Prince George’s Country, MD The 2014 Prince George’s County, Maryland, MS4 permit requires the permittee to submit for review and approval by the state a restoration plan for each WLA approved by EPA prior to the permit’s effective date

. The permit requires that each restoration plan: (1) include the final date for meeting applicable WLAs and a detailed schedule for implementing all structural and nonstructural measures necessary for meeting applicable WLAs; (2) provide detailed cost estimates for individual projects, programs, controls, and plan implementation; (3) evaluate and track implementation of restoration plans toward meeting established benchmarks, deadlines, and stormwater WLAs; and (4) develop an ongoing iterative process for focusing in on areas where the WLAs are not being met according to benchmarks and deadlines established as part of the County’s watershed assessments

. Note that in another section of the permit, the County is required to specify pollutant load reduction benchmarks for each watershed that demonstrate progress toward meeting all applicable stormwater WLAs

. See Sections III.E.1.b.v and E.2

. 

## Washington, DC The 201 1 DC MS 4 permit requires the permittee to submit for review and approval no later than 30 months after the effective date of the permit modification a consolidated TMDL Implementation Plan to address all TMDL WLAs applicable to District waters, with a focus on 15 specific TMDL s affecting the MS4’s discharge, but also to evaluate other pollutants of concern for which relevant WLAs exist

. Further, the permittee is required to submit an annual updated Consolidated TMDL Implementation Plan to account for any new or revised TMDL WLAs

. See Section 4.10

. 

### 4.2 **Monitoring/Modeling Requirements** A number of permits are starting to require their MS4s, which are identified and assigned allocations in TMDLs, to monitor 2 for the associated pollutant(s) of concern or, in others, to model the effects of stormwater controls on the discharge of pollutant(s) of concern

. Some of these requirements are specific to the pollutant parameter, while others dictate that the

2 Note that while many Phase I MS4 permits include monitoring requirements, these have generally not been, until relatively recently, included for the purposes of implementing TMDLs.

29

### Water Quality

- Based Effluent Limitations 

## Section B

permittee establish a monitoring program of its own to determine progress towards meeting applicable WLAs

. 

## General Permits California The 2013 California general permit for discharges from small MS4s includ es tailored requirements for monitoring in certain watersheds

. The permit specifies which permittees are affected by the tailored requirements, and the receiving streams where the monitoring must be performed

. In some watersheds, the monitoring is intended to establish baseline pollutant loading information, while in a number of others, the monitoring program (which is submitted to the state as part of a Wasteload Allocation Attainment Program) is intended show whether the MS4’s program is meeting interim t argets or WLA

- based limits

. In a number of watersheds, in addition to the effluent monitoring requirements, permittees are required to submit a quantifiable numeric analysis demonstrating that the BMPs selected for implementation will likely achieve the ap plicable WLA according to the schedule for implementing the TMDL , based on modeling, published BMP pollutant removal performance estimates, best professional judgment, and/or other available tools

. See, for example, the permit requirements for the San Lorenzo River TMDL for sediment in Appendix G

. See Attachment G – Region Specific Requirements, Regional Water Board Approved TMDLs

— where urban runoff is listed as a
source
. 

## Georgia The 2012 Georgia general permit for discharges from small MS4s requires permittees with a population of > 10,000 that discharge to an impaired water either with or without an approved TMDL to implement a monitoring plan for all pollutants of concern

. The monitoring plan, which must be submitted to the permitting authority for review and approval, is required to specify the sampling locations, sample type and frequency, implementation schedule, and t he BMPs that will be implemented to control and reduce the pollutants of concern

. Annual reports are required to include an assessment of the data trends for each pollutant of concern

. The assessment must initially include a characterization of baseline co nditions to determine the effectiveness of the BMPs employed and what, if any, additional adaptive BMP measures may be necessary to return the waters to comply with s tate water quality standards

. See Section 4.4.2

. 

## Pennsylvania The 2013 Pennsylvania general permit for discharges from small MS4s requires permittees to report on the progress of implementation of applicable MS4 TMDL Plans by submitting to the

30

### Water Quality

- Based Effluent Limitations 

## Section B

permitting authority either annual or progress reports. (Further description of reports found in NOI Instructions .) The permit requires the reports to include the reductions in pollutant load attained by implementation of the TMDL control measures and BMPs, broken down measure by measure and BMP by BMP. The report must demonstrate that measurable progress toward meeting the required pollutant load reductions are being achieved and are consistent with the conditions and assumpti ons of the applicable TMDL

. See Section II.F.2 (NOI Instructions). 

## Washington The 201 3 Western Washington small MS4 general permit requires a numbe r of its permittees to conduct discharge or surface water monitoring for fecal coliform and to electronically submit the results to the state

. See Appendix 2

. 

## Individual Permits Atlanta, GA Georgia’s Phase I MS4 permits require MS4s to propose a monitoring and implementation plan for each pollutant of concern

. The plan must include a map showing the monitoring locations and must specify the sample type and frequency

. Each a nnual r eport shall include an assessment of the data trends for each pollutant of con cern. The assessment shall initially include a characterization of baseline conditions to determine the effectiveness of the BMPs employed and what, if any, additional adaptive BMP measures may be necessary to return the waterbody to compliance with s tate water quality standards

. See, for example, Part 3.3.7 of the Bibb County, GA MS4 permit and Part III.E. of the Atlanta, Georgia, permit.

P ermits available upon request: Frances.Carpenter@dnr.state.ga .us 

## Nashville, TN Th e 2012 Nashville, Tennessee, MS4 permit includes specific monitoring instructions for waters impaired for siltation and/or habitat alteration, and pathogens

. For example, for siltation and habitat alteration impairments, biological stream sampling must be performed utilizing the Semi

- Quantitative Single Habitat Method (October 2006)

. For pathogen impairments, samples must be performed using methods identified in the permitting authority’s Quality System Standard Operating Procedure for Chemical and Bacteriological Sampling of Surface Waters (December 2009), and they must include the collection of 5 samples and corresponding flow measurements, within a 30

- day p eriod and must be performed between June through September (Summer)

. The permit also requires Visual Stream Surveys and Impairment Inventories on streams impaired for siltation, habitat alteration, and pathogens immediately upstream and downstream of each MS4 outfall to identify and prioritize MS4 stream impairment sources

. See 4.1 and 4.2

.

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### Water Quality

- Based Effluent Limitations 

## Section B

Florida Phase I Permits Florida’s Phase I MS4 permits require the MS4 for waterbodies with an approved TMDL, but without a BMAP , to submit to the state for review and approval a TMDL monitoring and assessment plan within one year

. The permit s specif y the minimum elements of the p lan , which include:

• Develop a table showing the annual loadings currently discharged from outfalls into waterbodies with an adopted TMDL;

• Rank the outfalls, based on total annual loading of the pollutant(s) of concern, discharging into each waterbody with an adopted TMDL; and

• Based on a review of sediment and biological monitoring results from the past, vali date the results of the loading assessment that identifies the highest priority outfalls

. Once the monitoring and assessment plan is approved, the permit s require storm event monitoring for a minimum of seven storm events at the top

- ranked outfall identifi ed in the plan to validate the estimates of annual pollutant loadings

. A final report summarizing the results must be submitted for review and approval by the state

. S ee , for example, Parts VIII.B.3.b and c of the 2013 Pinellas and 2011 Miami

- Dade Phase I MS4 permits

. Contact state for permit. 

## Prince George’s County, MD The 2014 Prince George’ s County, Maryland, MS4 permit requires the permittee to conduct monitoring to track progress toward meeting TMDLs, specifically chemical, physical, and biological monitoring in the Bear Branch watershed and an assessment of the effectiveness of stormwater controls for stream channel protection in the Black Branch watershed

. The permit includes specific protocols to be followed based on the type of monitoring

. For each annual report, the permittee must submit information on the results of the monitoring as well as pollutant load reductions related to applicable WLAs

. See Part IV.F and V.A

. See also similar requirements in Part IV.F of the 2013 Baltimore County, MD MS4 permit

. 

## Tucson, AZ The 2011 Tucson, Arizona, MS4 permit requires the MS4 to conduct monitoring at least two times during the first year of the permit to evaluate the effectiveness of control measures by comparing the phosphorus loads in stormwater with the applicable WLAs in the TMDL

. The target value for ortho

- phosphorus based on the WLA in the TMDL is 0.139 lbs/day minus the load contributed by the added ground water

. See Part 6.2.

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### Water Quality

- Based Effluent Limitations 

## Section B

Contact state for permit.


### 4.3 **TMDL**
**- Related Annual Reporting Requirements**  Several permits require MS4s that are subject to TMDLs to report on progress made towards implementing required management measures related to the TMDL

. These approaches provide the permitting authority with data and other information that can be used to determine what kind of progress is being made towards achievement of the TMDL

. The following are examples of this type of requirement

. 

## General Permits Arizona The 2002 Arizona general permit for discharges from small MS4s requires as part of the annual report for permittees to include a description and schedule for implementation of additional BMPs that may be nece ssary, based on monitoring results, to ensure compliance with applicable TMDLs

. See Section V.G.1.f

. 

## Arkansas The 2009 Arkansas general permit for discharges from small MS4s requires permittees to report on progress on program implementation and reducing the pollutant of concern and updates to measurable goals for the pollutant of concern reduction program elements

. See Section 3.4.5

. 

## California Th e 2013 California general permit for discharges from small MS4s requires permittees to report annually on the status of implementation of sp ecific TMDL components

. The report must include: (1) A description of BMPs implemented, including types, number, and locations; (2) An assessment of the effectiveness of implemented BMPs in progressing towards attainment of WLAs within the TMDLs’ specified timeframes; (3) All monitoring data, including a statistical analysis of the data to assess progress towards attainment of WLAs within the TMDLs’ specified timeframes; and (4) Based on results of the effectiveness assessment and monitoring, a description of the additional BMPs that will be implemented to attain WLAs within the TMDLs specified timeframes

. See Section E.15.d

. 

## Georgia The 2012 Georgia general permit for discharges from small MS4s requires MS4 permittees with populations over 10,000 that discharge to impaired waters with or without a TMDL to include an assessment of the data trends for each pollutant of concern i n their annual reports

. The initial a nnual r eport must also include a characterization of baseline conditions to determine

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### Water Quality

- Based Effluent Limitations 

## Section B

the effectiveness of the BMPs employed and what, if any, additional adaptive BMP measures may be necessary to return the waters to compliance with s tate water quality standards

. See Section 4.4.2

. 

## Minnesota The 2013 Minnesota general permit for discharges from small MS4s requires the following to be included in the annual report: (1) a list of all BMPs being applied to achieve the applicable WLA (including a unique identifier and geographic coordinate); (2) stage of implementation for each BMP; (3) updated estimate of the cumulative reductions in load ing achieved for each pollutant of concern; and (4) updated narrative describing any adaptive management strategies used for making progress to achieve applicable WLA

. See Part III.E and IV.B

. The state also provides specific TMDL reporting forms and training for using the forms

. 

## Nevada The 201 0 N evada g eneral permi t for d ischarges f rom s mall MS4s requires permittees t o in clude in their a nnual r eports a n update on a ll c ontrol measures being i mplemente d to a ddress applicable W LAs, and estimated r eductions of po llutants of concern

. See Section II. B.2.e and f

. 

## Individual Permit s Prince George’s Country, MD The Prince George’s County, M aryland, MS4 permit requires the permittee to submit an annual TMDL assessment report that includes complete descriptions of the analytical methodology used to evaluate the effectiveness of the County’s restoration plans toward achieving implementation of EPA

- approved TMDLs

. The County is also required to provide: (1) estimated net changes in pollutant load reductions from all completed water quality improvement projects, enhanced stormwater management programs, and alternative stormwater control initiative s; (2) a comparison of the net change in pollutant load reductions with the established benchmarks, deadlines, and applicable stormwater WLAs; (3) itemized costs for completed projects, programs, and initiatives to meet established pollutant reduction benc hmarks and deadlines; (4) cost estimates for completing all projects, programs, and alternatives necessary for meeting applicable stormwater WLAs; and (5) a description of additional watershed restoration actions that can be enforced when benchmarks, deadl ines, and applicable stormwater WLAs are not being met or when projected funding is inadequate

. See Section III.E.4

.

34

### Water Quality

- Based Effluent Limitations 

## Section B

**5. Requirements for discharges to impaired waters prior to**  **TMDL approval** Several permits identified specific actions that must be taken to address impaired waters prior to completion of an approved TMDL

. The following examples exhibited this approach

. 

## General Permits Arkansas
The 200 9 Arkansas general permit for discharges from small MS4s specifies required actions that must be taken by permittees that discharge to impaired waters for nutrients, bacteria, or other pollutants of concern prior to the completion of the TMDL

. For instance , for bacteria impairments, the permittee is required to take the following actions:

• Within 1 year, identify potential significant sources of bacteria entering the MS4;

• Within 2 years, develop and implement a public education program to reduce the discharg e of bacteria in municipal stormwater contributed by: (1) pets, recreation and exhibition livestock, and zoos; and (2) on

- site wastewater treatment systems;

• Within 2 years, review results from the Illicit Discharge Detection and Elimination ( IDDE ) program and modify as necessary to prioritize the detection and elimination of discharges contributing bacteria to the MS4; and

• Include in annual reports updates to measurable goals for bacteria reduction program elements

. See Sections 3.4.5 and 3.4.5.2

. 

## Californi a The 2013 California general permit for discharges from small MS4s requires permittees to implement additional procedures for discharges to impaired waters:

• For the construction site inventory, provide the location of the project with respect to all waterbodies listed as impaired for sediment and turbidity (Section E.10.a); and

• For the post

- construction BMP condition assessment, the permittee is required to give higher priority for maintenance to BMPs designed to remove pollutants for which the receiving water is impaired (Section E.12.ii.b)

. In addition , permittees that discharge to waters listed as impaired where urban runoff is listed
as a s ource must consult with the permitting authority within one year of permit coverage to

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### Water Quality

- Based Effluent Limitations 

## Section B

assess whether monitoring is necessary and, if so, the appropriate monitoring plan

. Section E.13.c

. 

## Georgia
The 2012 Georgia general permit for discharges from small MS4s requires existing permittees discharging to impaired waters to develop and submit for review and approval to the permitting authority an Impaired Waters Plan (for MS4s with a population of < 10,000) or a Monitoring and Implementation Plan (for MS4s with a population of > 10,000)

.

• The Impaired Waters Plan, which must be submitted by a specific date, must include a list of the impaired waters and the pollutant(s) of concern, a map showing the locations of the impaired waters and all MS4 outfalls discharging to those waters, BMPs that will be implemented to address each pollutant of concern, and a schedule for implementing the BMPs

.

• The Monitoring and Implementation Plan, which also must be submitted by a specified date, must identify where wet weather monitoring will occur, sample type, frequency, schedule to begin monitori ng, and a description of the BMPs that will be implemented to address each pollutant of concern. The permittee is also required to annually check whether an impaired water within its permitted area has been added to the latest 305(b)/303(d) list

. Newly lis ted waters must be addressed in the plan and the SWMP must be revised accordingly

. See Section 4.4.2

. 

## Individual Permits Baton Rouge, LA The 2009 Baton Rouge, Louisiana, permit requires the MS4 to develop an Interim Pollutant Reduction Plan for discharges of a pollutant on a 303(d) list prior to completion of a TMDL. Specific activities and dates are specified when the pollutant is a nutrient constituent, for bacteria, or another pollutant (for example, identify potential sources of nutrient pollutant withi n 1 year, develop a public education program for residential/commerci al uses of fertilizers within 2 years, develop a program to reduce discharge of nutrients from municipal facilities within 2 years, etc.)

. See Part II.B.1. Contact state for permit.

36