Drain with Fish Graffiti

The intent of this paper is to provide a basic understanding of the recently reissued MS4 permits in Illinois.

A brief history of stormwater regulations includes the federal Clean Water Act (CWA) of 1972 which was implemented by the United States Environmental Protection Agency (USEPA) and established the National Pollutant Discharge Elimination System (NPDES) Permit Program. Then, in 1987 the reauthorization of the CWA required the regulation of stormwater point discharges be addressed through the NPDES permit program.

In 1990, Phase 1 of the reauthorization of CWA required medium and large cities, or certain counties with populations of 100,000 or more, to obtain a NPDES permit for stormwater discharges from their municipal separate storm sewer systems (MS4s). MS4s are a conveyance – or a system of conveyances – owned by a state, city, town, village or other public entity, and discharges into waterways. MS4s are also designated to collect or convey stormwater (including storm drains, pipes, ditches, ponds, etc.) Rockford, IL is an example of a “large city” MS4 included in Phase 1.

Phase 2 (implemented in 2000) revised every permit cycle to require regulated small MS4s obtain NPDES permits for their stormwater too. All other MS4s in Illinois (excluding Rockford) were included in Phase 2.

All MS4s in Illinois are regulated by the NPDES permit program, and must abide by permit number ILR40 – the Illinois NPDES permit for the discharge of stormwater. The term of ILR40 is five (5) years and it has the CWA as its legal basis.


PART 1 – Coverage Under General Permit

This section requires submittal of the Notice of Intent (NOI) to the Illinois Environmental Protection Agency (IL EPA) within 90 days. The permit holder is authorized to discharge stormwater from their small MS4 under the terms and conditions of the permit 30 days after the date the NOI is received.

PART 2 – Notice of Intent (NOI) Requirements

This section requires a new NOI (if requested) within 90 days of effective date (using the form on the IL EPA website). You must include the name and segment number of receiving water(s) and list:

  • Any impaired waters (303d list),
  • Any associated with total maximum daily load (TMDL), and
  • Any associated with watershed management plans.

PART 3 – Special Conditions

Discharges shall not cause water quality violations. For total maximum daily load (TMDL)/watershed management plan approved water bodies, the permit requires an assessment of stormwater management as well as a plan that assures TMDL allocations are being met. If allocations are not being met, a plan that revises and monitors discharges must be included. Deicing activities are also a part of this section. Please note: If MS4 owners apply for an ILR40 and are denied coverage, there are opportunities to apply for an individual permit.

PART 4 – Stormwater Management Programs (SWMP)

This section requires permit holders to implement and enforce SWMPs by using some or all of the following:

  • Implementing an ordinance or other regulatory mechanism to address post-construction runoff from new development and redevelopment projects, public surfaces, and existing developed property.
  • Require all regulated construction sites to have post-construction management plans that meet or exceed the requirements of Part IV.D.2.h of NPDES permit ILR10 including management practices, controls, and other provisions at least as protective as the requirements contained in the most recent version of the Illinois Urban Manual.
  • Ensure adequate long-term operation and maintenance of BMPs.
  • [By March 1, 2019], implement a process to assess the water quality impacts in the design of all new and existing flood management projects that are associated with the permit holder or that discharge to the MS4.

PART 5 – Monitoring, Recordkeeping & Reporting

The permit holder must implement a monitoring program to evaluate the effectiveness of the BMPs being implemented. The program may include:

  • An evaluation of BMPs based on estimated effectiveness from published research accompanied by an inventory of the number and location of BMPs implemented as well as an estimate of pollutant reduction resulting from the BMPs
    – OR –
  • A determination of the effectiveness of control measures. The monitoring of stormwater discharges, and ambient monitoring intended to gauge stormwater impacts, shall be performed within 48 hours of a precipitation event greater than or equal to one (1) quarter inch in a 24-hour period. At a minimum, analysis of stormwater discharges or ambient water quality is required to include total suspended solids, total nitrogen, total phosphorus, fecal coliform, chlorides, and oil and grease. In addition, monitoring should be performed for any other pollutants associated with stormwater runoff for which the receiving water is considered impaired pursuant to the most recently approved list under Section 303(d) of the Clean Water Act. Permit holders serving a population of 25,000 or less may conduct visual observations of stormwater discharge, documenting the aforementioned parameters in lieu of the water quality monitoring.

PART 6 – Definitions and Acronyms

SWMP – stormwater management plan
MS4 – municipal separate storm sewer system
CWA – clean water act
BMP – best management practice
NPDES – National Pollutant Discharge Elimination System
NOI – notice of intent
NOT – notice of termination
TMDL – total maximum daily load
SWPPP – stormwater pollution prevention plan
WQS – water quality standard
USEPA – United States Environmental Protection Agency
Environmental Justice – fair treatment and meaningful involvement of all people regardless of race, origin or income
Environmental Justice Area – community with low income and/or minority population greater than twice statewide average

ATTACHMENT H – Standard Conditions

  • More definitions and other legal requirements.
  • All a permit holders should read this section.

Illinois NPDES Permit Number ILR40

Each MS4 permit holder must address six (6) minimum control measures comprised of best management practices (BMPs) that include:

  1. Public education and outreach focusing on stormwater impacts.
  2. Public involvement and participation.
  3. The identification and elimination of illicit discharges including in sanitary sewers connected to storm sewers.
  4. Control construction site runoff by using erosion control as well as other BMPs.
  5. Control stormwater runoff from development and redevelopment using stormwater ordinances and standards.
  6. Reduce pollutant runoff from municipal/government operations by implementing BMPs at public works facilities.

REQUIREMENT #1: Public Education and Outreach on Stormwater Impacts

Permit holders are required to distribute educational materials and/or conduct outreach activities regarding the impacts of stormwater discharges on water to the community. The materials must include a statement on the benefits and costs of starting pollution prevention measures and how to implement them. And, at a minimum, the permit holder is required to provide:

  • Information on the effective pollution prevention measures including these topics:
    • Storage and disposal of fuels, oils and similar materials used in the operation of vehicles and other equipment;
    • Use of soaps, solvents or detergents used in the outdoor washing;
    • Paint and related décor;
    • Lawn and garden care; and
    • Winter deicing material storage and use.
  • Information on the potential impacts on stormwater discharge due to climate change.
    Information about green infrastructure strategies such as green roofs, rain gardens, rain barrels, bioswales, permeable piping, dry wells, and permeable pavements.

REQUIREMENT #2: Public Involvement & Participation

  • At a minimum, permit holders must comply with State and local public notice requirements when implementing a public involvement/participation program.
  • Permit holders must provide a minimum of one (1) public meeting annually to collect input regarding the adequacy of the MS4 program.
  • Permit holders must also identify environmental justice areas (i.e. minority populations) within the permit holders’ jurisdiction and include appropriate public involvement/participation.

NOTE: These requirements may be met in conjunction with or as part of a regular council or board meeting.

REQUIREMENT #3: Illicit Discharge Detection and Elimination

Permit holders are required to develop and enforce a program to detect and eliminate illicit connections or discharges into the permit holders small MS4. The permit holder may establish a prioritization plan for inspection of outfalls; placing priority on outfalls with the greatest potential for non-stormwater discharges. Major/high priority outfalls shall be inspected at least annually. The following are BMPs used to assure this requirement:

  • Develop/maintain/update, a storm sewer system map with outfalls identified.
  • To the extent applicable under law, prohibit through ordinance, or other regulatory mechanism, non-stormwater discharges into the MS4. Implement appropriate enforcement procedures including requirements for the prompt reporting to the MS4 of all unpermitted discharges and a program to be responsive to any reports.
  • Develop and implement a plan to detect and address non-stormwater discharges, including illegal dumping, to the system.
    Inform employees, businesses, and the general public of hazards associated with illegal discharges and improper disposal of waste.
  • Address the categories of non-stormwater discharges (listed in Section l.B.2 of the permit) if you identify them as a significant contributor of pollutants to your small MS4.
  • Conduct periodic inspections of the storm sewer outfalls in dry weather conditions for detection of non-stormwater discharges.

REQUIREMENT #4: Control Construction Site Runoff

All regulated construction sites must have a stormwater pollution prevention plan (SWPPP) that meet the requirements of Part IV of NPDES permit number ILR10 and are at least as protective as the requirements contained in the Illinois Urban Manual (or as amended) including green infrastructure techniques.

  • Include procedures for site plan reviews which incorporate consideration of potential water quality impacts and review of individual pre-construction site plans to ensure consistency with local sediment and erosion control requirements.
  • Procedures for receipt and consideration of information submitted by the public.
  • Site inspections and enforcement of ordinance provisions.
  • To reduce pollutants in stormwater runoff from construction activities that result in a land disturbance of greater than, or equal to, one (1) acre, the permit holder must develop and implement the following:

An ordinance, or other regulatory mechanism, to require erosion/sediment controls, as well as include sanctions to ensure compliance. Controls must address factors such as the amount, frequency, intensity and duration of precipitation, the nature of resulting stormwater runoff, and soil characteristics, including the range of soil particle sizes expected to be present on the site.
Ensure the construction site owner/operator maintains effective erosion controls and sediment controls. At a minimum when feasible, controls must:

  • Control stormwater volume and velocity to minimize soil erosion.
  • Control stormwater peak flow rates and total volume discharges to minimize erosion at outlets and streams.
  • Minimize the amount of soil exposed during construction activity.
  • Minimize the disturbance of steep slopes.
  • Minimize sediment discharges from the site.
  • Minimize soil compaction and preserve topsoil.
  • Provide and maintain natural buffers around surface waters, direct stormwater to vegetated areas, and maximize stormwater infiltration. Infiltration practices should not be implemented in any of the following circumstances:
  • Areas where vehicle fueling and/or maintenance occur.
  • Areas with shallow bedrock which allows movement of pollutants into the groundwater.
  • Areas near Karst features.
  • Areas where contaminants in soil or groundwater could be mobilized by infiltration of stormwater.
  • Areas with a delineated source water protection area for public drinking water supply where the potential for an introduction of pollutants into the groundwater exists.
  • Areas within 400 feet of a community water supply well if there is not a wellhead protection delineation area or within 200 feet of a private water supply well.
  • Construction site operators should also be required to control or prohibit non-stormwater discharges that would include:

Concrete and wastewater from washout of concrete, drywall compound, stucco, paint, form release oils, curing compounds and other construction materials, Oils, or other pollutants used in vehicle and equipment operation and maintenance, Soaps, solvents, or detergents, toxic or hazardous substances from a spill or other release, or Any other pollutant that could cause or tend to cause water pollution.

REQUIREMENT #5: Control stormwater runoff from development and redevelopment using stormwater ordinances and standards

When selecting BMPs to comply with the requirements for construction and post-construction management, the permit holder is required to adopt one (1) or more of the following general strategies (listed in order of preference below). The chosen strategies must also include rationale for not selecting an approach with a higher preference.

  • Preservation of the natural features of development sites, including natural storage and infiltration characteristics.
  • Preservation of existing natural streams, channels, and drainage ways.
  • Minimization of new impervious surfaces.
  • Conveyance of stormwater in open vegetated channels.
  • Construction of structures that provide both quantity and quality control, with structures serving multiple sites being preferable to those serving individual sites.
  • Construction of structures that provide only quantity control, with structures serving multiple sites being preferable to those serving individual sites.

MS4 permit holders are required to implement a program to minimize the volume of stormwater runoff and pollutants from public highways, streets, roads, parking lots, and sidewalks (public surfaces) if they manage, or are directly involved in, (or who supervise others who manage, or directly involved in), the routine maintenance, repair or replacement of public surfaces. The program is required to include the two (2) annual training sessions outlined below:

  • Annual training for all MS4 employees in current green infrastructure or low impact design techniques.
  • Annual training for all contractors retained in current green infrastructure or low impact design techniques. Contractors may provide training to their employees.
  • Again, under Requirement #5, permit holders are asked to implement a program to help minimize the volume of stormwater runoff and pollutants from privately owned property within the MS4 jurisdiction. Such program must be directed to the affected property owners, must be documented and may contain the following elements:
    • Property owners receive education on green infrastructure BMPs including the management of pesticides and fertilizers.
    • Permit holders must provide an inventory of stormwater pollutants discharged to the MS4.
    • Permit holders provide an evaluation of existing flood control techniques to determine the feasibility of pollution control retrofits.
    • Permit holders must provide an evaluation of existing flood control techniques to determine the potential effects due to climate change.
    • Permit holders are required to implement additional controls for special events expected to generate significant pollution (fairs, parades, performances) as well as maintenance programs (including maintenance agreements, for structural pollution control devices or systems).
    • Permit holders should arrange for street cleaning in targeted areas.
    • Post-Construction Stormwater Management in New Development and Redevelopment

Similar rules apply to new development and redevelopment. Permit holders are required to implement and enforce a program to address and minimize the volume and pollutant load of stormwater runoff that disturb greater than or equal to one (1) acre (or that have been designated to protect water quality), that discharge into the MS4’s jurisdictional control.

REQUIREMENT #6: Reduce pollutant runoff from municipal/government operations by implementing BMPs at public works facilities

The below BMPs are suggestions for municipal operators of MS4s to assist in complying now and in the future.

Develop and implement an operation and maintenance program that includes an annual training component for municipal staff and contractors and is designed to prevent and reduce the discharge of pollutants to the maximum extent practicable.
Design, install, implement, and maintain effective pollution prevention measures, including:

  • Minimize the discharge of pollutants from equipment and vehicle washing, including wheel wash water, and other wash waters. Wash waters must be treated in a sediment basin or alternative control that provides equivalent or better treatment prior to discharge.
  • Minimize the exposure to precipitation and stormwater of building materials, construction wastes, trash, landscape materials, fertilizers, pesticides, herbicides, chemical storage tanks, deicing material storage facilities and temporary stockpiles, detergents, sanitary waste, and other materials present on site.
  • Minimize the discharge of pollutants from spills and leaks and implement chemical spill and leak procedures.
  • Provide regular inspection of municipal stormwater BMPs. Based on inspection findings, the permit holder is required to determine if repair, replacement, or maintenance measures are necessary in order to ensure the structural integrity, proper function, and treatment effectiveness of structural stormwater BMPs.
  • Deicing material must be stored in a permanent or temporary storage structure or seasonal tarping must be utilized. If no permanent structures are owned or operated by the permit holder, new permanent deicing material storage are required to be constructed within two (2) years of the effective date of the permit. Storage structures or stockpiles shall be managed to minimize stormwater pollutant runoff from the stockpiles or loading/unloading areas of the stockpiles. Stockpiles and loading/unloading areas should be located as far as practicable from any area storm sewer drains. Fertilizers, pesticides, or other chemicals are also required to be stored indoors.
  • Using training materials available from the USEPA, the state of Illinois, or other organizations, the permit holder’s annual program to reduce and prevent stormwater pollution must include:
    • Employee training,
    • Fleet and building maintenance,
    • Operation of storage yards,
    • Snow disposal,
    • Deicing material storage handling and use on roadways,
    • New construction and land disturbances, and
    • Stormwater system maintenance procedures for proper disposal of street cleaning debris and catch basin material.
      In addition, training should include how flood management projects impact water quality, non-point source pollution control, green infrastructure controls, and aquatic habitat.

NPDES Permit Number ILR40 – Monitoring and Reporting

The ILR40 is structured around six (6) minimum control measures that include monitoring and reporting to regulatory agencies to document progress on goals by June 1st each year (Phase I communities have additional requirements). The annual report should be submitted electronically (epa.ms4annualinsp@illinois.gov) and must include:

  • An explanation of the compliance with permit conditions, including an assessment of the BMPs and progress toward measurable goals;
  • Results of any collected and analyzed data;
  • A summary of the stormwater activities planned for the next reporting cycle;
  • A change in any identified BMPs or measurable goals; and
  • If applicable, information regarding another governmental entity(ies) prompted to satisfy some of the permit obligations.

In conclusion, stormwater management is complex and important. CMT professionals are experts in stormwater management and can guide you through this process to help your MS4 achieve your water quality goals.

Authored by,
Timothy Sumner, PE, CFM, CSM
Water Resources Project Manager and Engineer
Crawford, Murphy & Tilly (CMT)