1. Understanding Total Maximum Daily Loads with Stormwater Sources and the NPDES Stormwater Permitting Process U.S. Environmental Protection Agency

2. Learning Objectives Provide an overview of TMDLs and NPDES stormwater permitting Provide an understanding of how TMDL writers can address stormwater in TMDL development Provide an understanding of how NPDES permit writers can develop permits to implement TMDLs 2

3. Presentation Roadmap Overview of the TMDL program Overview of the NPDES stormwater permitting process Basics of TMDL and stormwater permit integration What’s different about TMDLs for stormwater sources? What’s different about stormwater permits to implement TMDLs? Quiz 3

4. Overview of Total Maximum Daily Loads (TMDLs) Wasteload allocations (WLAs) set loading cap for point sources Load allocations (LAs) set loading cap for nonpoint sources Reserve capacity sets aside allocation for future development Margin of Safety (MOS) allocation accounts for uncertainty 4 Point Source #1 Point Source #2 Point Source #3 Nonpoint Source #1 Nonpoint Source #2 Nonpoint Source #3 Nonpoint Source #4 MOS Reserve Capacity

5. Wasteload Allocations (WLAs) WLA used to determine WQBEL WQBEL implemented through NPDES permits 5 Point Source #1 Point Source #2 – WLA MOS Reserve Capacity Point Source #3 Nonpoint Source #1 Nonpoint Source #2 Nonpoint Source #3 Nonpoint Source #4

6. Brief Overview of Regulated Stormwater Sources Three primary types of sources (40 CFR 122.26(a) and 122.26(b)) Municipal separate storm sewer systems (MS4s) Construction Industrial Other sources as designated by the permitting authority Two types of NPDES stormwater permits Individual General 6

7. Types of NPDES Permits Individual Permit 1 application submitted  1 permit issued Appropriate where discharger needs site- specific permit conditions Public Notice and Public Comments Administrative Record Permit Application Draft Permit and Fact Sheet Development Effluent Limits Monitoring Conditions Standard Conditions Special Conditions Draft Permit and Fact Sheet Development Effluent Limits Monitoring Conditions Standard Conditions Special Conditions Final Permit

8. Types of NPDES Permits General Permit 1 permit issued  many applications submitted Appropriate where multiple dischargers require relatively uniform permit conditions Public Notice and Public Comments Administrative Record Identify Need and Collect Data Draft Permit and Fact Sheet Development Effluent Limits Monitoring Conditions Standard Conditions Special Conditions Draft Permit and Fact Sheet Development Effluent Limits Monitoring Conditions Standard Conditions Special Conditions Final Permit Notice of Intent (NOI) to be Covered

9. Overview of Regulated Stormwater Sources: MS4s Not just municipalities Phase I MS4s Based on population served (100,000+) Individual permit with detailed application process Phase II MS4s Small regulated MS4s within the boundaries of an ‘urbanized area’ or designated by permit authority Two permit types MS4 general permit with 6 minimum control measures Individual permit under special circumstances 9

10. Overview of Regulated SW Sources: Construction Phase I: disturb 5 acres or more Phase II: disturb between one and 5 acres Permit types Construction General Permit (CGP) Individual permits are an option under certain conditions Discharge to impaired waters Reasonable potential to cause or contribute to water quality standard exceedance 10

11. Overview of Regulated SW Sources: Industrial Activity Eleven categories of industrial activity Covered under multi-sector general permit (MSGP), although individual permits are an option under certain conditions Able to certify to a condition of no exposure in lieu of permit coverage 11

12. Permitting Other SW Sources: Residual Designation Authorizes NPDES permitting authorities to designate other stormwater sources for permit coverage Cause or contribute to water quality standard excursion Significant contributor of pollutants to surface waters Implications for how TMDLs are developed that include both regulated and currently unregulated stormwater sources 12

13. Let’s Review... Three types of regulated stormwater sources MS4s (Phase II MS4 GP) Industrial (MSGP) Construction (CGP) Other sources using RDA Stormwater sources assigned WLAs WLAs translated to WQBELs in permits 13

14. Basics of TMDL & Stormwater Permit Integration WLAs for regulated stormwater sources Needed to promote effective implementation As specific for each regulated stormwater source as possible NPDES stormwater permits must be consistent with assumptions and requirements of WLAs TMDL and permit writers should work together throughout the process 14

15. TMDL Process 15 Stakeholder Involvement & Public Participation Linkage between Loading and Waterbody Response Allocation Analysis TMDL Report and Submittal 1. Description of waterbody, pollutant of concern, pollutant sources, and priority ranking 2. Water Quality Standards and numeric WQ target* 4. Load Allocations (LAs)* 5. Wasteload Allocations (WLAs)* 6. Margin of Safety (MOS)* 7. Seasonal Variation* 3.Loading Capacity- Linking WQ and Pollutant Sources* (including critical conditions*) 8.Reasonable Assurances + 9.Monitoring Plan + 10.Implementation Plan + 11. Public Participation* EPA Recommended Elements in a TMDL Submittal * Required by regulation (40 CFR 130.7) + Recommended through guidance From Guidelines for Reviewing TMDLs under Existing Regulations issued in 1992 (May 20, 2002): http://www.epa.gov/owow/tmdl/guidance/final52002.html Implementation and Monitoring Plan Problem Understanding TMDL Target Identification Source Assessment

16. Understanding SW Effects 16 Precipitation Interception Infiltration Percolation Transpiration Evaporation Surface Runoff Groundwater Return Flow

17. Understanding SW Effects 17

18. Understanding SW Effects Altered stream hydrology (“water quantity”) Higher peak flows Increased runoff volume Lower base flows Increased pollutant loading (“water quality”) Higher runoff volumes Exposure to stormwater sources Less opportunity for filtering 18

19. Impairment Characterization Waters impaired by stormwater sources often listed for: Biological impairment Habitat alteration Focus on multiple pollutants and combined effects Look at indicators of stormwater impacts Flow patterns Degraded biology/habitat Imperviousness 19

20. Establishing Water Quality Targets Water quality targets include… Indicator Associated target value Water quality targets for TMDLs with SW sources Consider multiple stressors due to changes in flow and increased pollutant loads Could lead to use of a surrogate target, such as impervious cover, that represents combined SW effects 20

21. Stormwater Source Assessment Challenging boundary issues Snapshot in time Construction sites ephemeral in nature Industrial source no-exposure status could change Less familiar point source databases eNOI state-specific stormwater database Data generated by sources varies by type and permit requirement 21

22. Understanding Spatial Boundaries of SW Sources MS4 system boundary ≠ municipal jurisdictional boundary Phase II regulated small MS4s only within urbanized area boundary Industrial and construction sources can be found in and out of MS4 boundaries

23. MS4 Generated Information 23

24. TMDL Approach Selection Similar approaches to consider Impairment/source specific information to consider Use of a surrogate target such as IC or flow volume Boundary/location of stormwater sources Behavior of stormwater sources Critical conditions 24

25. Categorizing Stormwater WLAs WLAs for other point sources are presented for each individual point source facility For regulated stormwater sources, TMDL writers might face challenges that limit their ability to provide individual WLAs for each regulated stormwater source 25

26. Challenges for Categorizing Stormwater Source WLAs Data availability Boundary issues Varied implementation approaches 26

27. Residual Designation Authority and WLAs Include language in the TMDL about potential changes in regulatory status Currently unregulated stormwater sources have load allocations Use of RDA to change designation means load allocation becomes a wasteload allocation No need for TMDL resubmission Might require WLA refinement Change in overall loading cap would be subject to approval 27

28. Options for Categorizing and Expressing WLAs Individual by each regulated stormwater source Categorical by each type of stormwater source Aggregated for all stormwater sources 28

29. Individual WLAs by Source: Overview 29

30. Tips: Individual WLAs by Source Ensure consistency between source characterization and source WLAs Provide information and assumptions about each source Provide estimated baseline load for each source Present WLA to support implementation 30

31. Categorical WLAs by Source Type: Overview 31

32. Tips: Categorical WLAs by Source Type Create regulated stormwater source inventory Indicate which regulated stormwater sources are included under each category Provide recommendations for sub-allocating the categorical WLAs Provide rationale for using this approach 32

33. Single Aggregated WLA for All Stormwater Sources: Overview 33

34. Tips: Single Aggregated WLA for All Stormwater Sources Create regulated stormwater source inventory Indicate which regulated stormwater sources are included under the aggregated WLA Provide recommendations for sub-allocating the aggregated WLA Provide rationale for using this approach 34

35. Mixing WLA Options Select options best suited to sources Data availability Permit requirements and implementation strategies Consider other options for further categorizing WLAs Subwatershed Dry weather/wet weather 35

36. WLA Challenges and Considerations by Source Type 36

37. MS4 WLA Challenges Regulated area based on system boundary Regulated area might have pockets that don’t drain to the regulated system Regulated area might contain nested sources 37

38. Charles River Pathogen TMDL MS4 WLA Includes 35 MS4s Assigns two WLAs to all MS4s for each type of surface waters Expresses WLA as colonies/day Calculated WLA using flow data from areas with impervious cover Captures combined sewer areas Presented on a segment-by- segment basis 38

39. Wissahickon Creek Siltation TMDL MS4 WLAs Covers 16 MS4s in five subwatersheds Estimates loads for five subwatersheds and distributes among MS4s Contains existing load, WLA, percent reduction for each MS4 Presents WLAs by subwatershed in appendix 39

40. Shingle Creek Chloride TMDL MS4 WLAs Covers deicing activities by multiple MS4s Nine municipalities One county MN Dept. of Transportation Includes categorical MS4 WLA Allows implementation flexibility 40

41. Construction Source WLA Challenges Varied timeframes for construction activities Change in source type after activity ends Activities located in MS4 boundary Activities located outside MS4 boundary 41

42. Potomac Drains (WV) Sediment TMDL Construction WLAs Identified 176 regulated construction sources at outset of TMDL Updated information during process with new active and pending permits Assigns individual WLAs to 297 regulated construction sources Includes future growth allowance 42

43. Industrial WLA Challenges Regulated industrial stormwater sources might be located in the MS4 boundary Regulated industrial stormwater sources might have a no exposure certification 43

44. Columbia Slough TMDLs Industrial WLAs Lead TMDL (1998) Aggregated WLA for permitted industrial area Provides an approach for industrial facilities to calculate their individual WLA Unit-area basis Dependent on flow conditions 44 Photo: Mark Gamba http://www.portlandmonthlymag.com/travel-and-outdoors/articles/1008-features-oasis /

45. Gauley River Watershed TMDL Industrial WLAs Iron/TSS WLAs (2008) Loads (lbs/yr) Concentrations (mg/L) Individual WLA assigned to each industrial facility Facilities have iron and TSS benchmark values under MSGP Facilities that meet benchmarks not considered a significant source Assigning WLA necessary to allow SW discharge under MSGP 45

46. NPDES Permit Components 46 Components of All Permits Cover Page Special Conditions Monitoring and Reporting Effluent Limitations Additional Monitoring / Special Studies Best Management Practices Standard Conditions Compliance Schedules Technology-based Water Quality-based

47. NPDES Permit Components Affected by TMDLs 47 Components of All Permits Cover Page Special Conditions Monitoring and Reporting Effluent Limitations Additional Monitoring / Special Studies Best Management Practices Standard Conditions Compliance Schedules Technology-based Water Quality-based

48. 48 40 CFR 122.44(d)(1)(vii) (vii) When developing water quality-based effluent limits under this paragraph the permitting authority shall ensure that: (A)The level of water quality to be achieved by limits on point sources established under this paragraph is derived from and complies with all applicable water quality standards; and (B)Effluent limits developed to protect a narrative water quality criterion, a numeric water quality criterion, or both, are consistent with the assumptions and requirements of any available wasteload allocation for the discharge prepared by the State and approved by EPA pursuant to 40 CFR 130.7.

49. Effluent Limits in Stormwater Permits Numeric limits Pollutant loads and concentrations Numeric parameters acting as surrogates for pollutants (i.e., impervious cover or flow) Narrative BMP limits Selected to meet the WLA Possibly includes requirement to monitor BMP performance against benchmarks 49

50. Options for Numeric Effluent Limits in Stormwater Permits Develop water quality-based effluent limitations (WQBELs) Incorporate WLA as numeric effluent limit (e.g., bacteria concentration or sediment percent reduction) 50

51. Options for Narrative Effluent Limits in Stormwater Permits Require implementation of BMPs in the permit Based on documented pollutant removal effectiveness Consider numeric performance benchmarks Incorporate specific BMPs identified in the TMDL or implementation plan Hybrid approach: meet narrative limits or be subject to numeric limits 51

52. Monitoring in Stormwater Permits Visual BMP installation inspections Discharges In-stream Analytical monitoring Discharge/Outfall BMP performance (flow, pollutant removal) Ambient 52

53. Compliance Schedules in Stormwater Permits Compliance schedule and interim limits might be necessary BMP implementation over time to meet WLA Time needed for compliance with numeric effluent limit Consult EPA’s memorandum “Compliance Schedules for Water Quality Based Effluent Limits in NPDES Permits” http://www.epa.gov/npdes/pubs/memo_complian ceschedules_may07.pdf) http://www.epa.gov/npdes/pubs/memo_complian ceschedules_may07.pdf 53

54. WLAs to MS4 Permit Example: Washington D.C. MS4 Permit Permit includes two different types of WQBELs that are linked to applicable TMDLs 1.Numeric effluent limit: Requires annual removal of 103,188 lbs of trash as defined by Anacostia River Watershed Trash TMDL 2.Other TMDL requirements Permit lists 15 TMDLs for BOD, fecal coliform, TSS, oil and grease, organics and metals, PCBs, trash, nutrients For all WLAs assigned to the DC MS4, the permittee to develop and submit a TMDL Implementation Plan for review and approval within 30 months of permit issuance (Section 4.10.3) 54

55. TMDL Implementation Plan Requirements (Section 4.10.3) Schedule of WLA attainment with interim milestones if longer than 5 years Numeric benchmarks Specify annual pollutant load reductions Extent of controls to achieve benchmarks Modeling to show how controls will achieve WLA Submit within 30 months of effective date for EPA review and approval EPA will incorporate approved plan as enforceable permit provisions Annual updates as needed to include new WLAs If insufficient progress is shown during permit term from effluent monitoring, adjustments to the Implementation Plan must be made within 6 months 55

56. Determining Applicability of the TMDL to SW Permits Permitting staff makes determination General permit application process guides permittee to determine: Receiving waterbody If receiving water is impaired or subject to a TMDL General permit contains list of TMDLs and applicable waterbodies 56

57. Considerations for Implementation Planning 1.) Establish baseline conditions/characterization Soils, geology Space constraints 2.) Identify potential BMPs based on project goals Flow/volume reduction Water quality treatment 3.) Analyze BMP opportunities and constraints 4.) Estimate cost 5.) Conduct targeting and optimization 57

58. Tools to Support Implementation Planning BMP Performance Evaluation Tool (EPA Region 1) Can estimate BMP pollutant load removal or size a BMP to meet specific pollutant removal target www.epa.gov/region1/npdes/stormwater/ SUSTAIN (EPA ORD) Identifies most cost-effective combinations of BMP type, location and size to meet specific flow and water quality targets www.epa.gov/nrmrl/wswrd/wq/models/sustain/ 58

59. WLAs to MS4 Permit Example: San Francisco Bay TMDLs 59

60. San Francisco Bay TMDL: WLAs for PCBs and Mercury PCB and Mercury TMDLs Identify “urban stormwater” as a source that contribute to the impairment Allocate county-wide loads for those identified as sources of urban stormwater discharges TMDL Implementation Plans Provide a 20-year timeline for meeting the WLAs Specify what must be included in NPDES permits Require implementation of BMPs designed to achieve WLA Specify requirements for permit reissuance based on an updated effectiveness of BMPs include technically feasible and cost-efficient controls to attain WLAs 60

61. San Francisco Bay PCB and Mercury TMDL Implementation Plans PCBs Implementation Plan 1st permit cycle – implement BMP pilots 2nd permit cycle – implement BMPs that protect strategic locations and develop plan to attain allocations Mercury Implementation Plan Identifies specific permit requirements that must be included in urban stormwater permits Example: develop and implement mercury source control program; monitor levels of methymercury in discharges 61

62. San Francisco Bay MS4 Permit (2009) Permit covers stormwater discharges from multiple municipalities and local agencies Includes both the minimum regulatory requirements (i.e., MS4 “six minimum measures”) and TMDL-based requirements (Sections C.9-C.14) for all impairment pollutants Pesticides, mercury, PCBs, copper Trash TMDL requirements in permit are directly linked to the Implementation Plans for each of the impairment pollutants 62

63. WLAs to SW Permit Limits: Mercury SW WLAs Assigned to 12 urban SW dischargers, listed by county or MS4 entity 20 yr deadline to achieve WLA with interim milestone Specifies that NPDES permits must require sources to implement BMPs designed to achieve WLA, including a set of minimum requirements Implement mercury source control program Implement monitoring system to quantify load reductions Monitor methylmercury in discharges Fate and transport study Develop allocation sharing mechanism Permit Limits Incorporates specific aggregate WLA and interim loading milestone 20 yr deadline for attainment of aggregate WLA and 10 yr deadline for interim loading milestone WQBEL in permit match requirements set out in Implementation Plan Additional WQBELs: Pilot projects to evaluate municipal sediment removal practices, on-site treatment systems through retrofits, and pollution abatement programs in stormwater conveyances 63

64. Tips for TMDL Developers and NPDES Stormwater Permit Writers Work together throughout the TMDL development process Promotes data sharing Encourages programmatic information exchange Identify all stormwater sources in the watershed affecting an impaired waterbody MS4s, traditional and non-traditional Construction site in and out of MS4 Industrial facilities in and out of MS4 64

65. Tips for TMDL Developers and NPDES Stormwater Permit Writers Address data gaps by developing suite of monitoring requirements for TMDLs and permits Express WLAs to promote effective implementation One WLA per stormwater source, if adequate data Talk to NPDES stormwater permitting staff about implementation details 65

66. Tips for TMDL Developers and NPDES Stormwater Permit Writers Determine whether to prescribe BMPs and where (TMDL v. permit) Assist stormwater permittees in finding impaired waterbodies and associated TMDL information Direct permittees to WLAs related to their discharges Provide guidance on BMP selection where narrative effluent limits are used 66

67. Resources  Technical assistance from EPA: www.epa.gov/owow/tmdl/stormwater/ www.epa.gov/owow/tmdl/stormwater/  Summary of State Practices  Summary of 17 TMDLs with SW sources  Understanding TMDL Requirements for MS4s  Stormwater TMDL Implementation Support Manual 67