Last Friday, the Environmental Protection Agency (EPA) finalized anticipated new stormwater discharge regulations, known more formally as the “2021 National Pollutant Discharge Elimination System (NPDES) general permit for stormwater discharges associated with industrial activity” and also referred to as the “2021 Multi-Sector General Permit (MSGP)”. The MSGP is updated every five years in accordance with MSGP requirements. While the 2021 MSGP is effective as of March 1, 2021 and only applies to Idaho, Massachusetts, New Hampshire, New Mexico, tribal lands, Puerto Rico, the District of Columbia, and most U.S. territories and protectorates, it also sets a baseline that many states follow when updating their stormwater regulations.


While NRMCA is still analyzing the new permit, some highlights from the new permit, compared to the 2015 permit, in part, include:

  • Restructuring from previous permit parts to “streamline” the permit for better “sequential” reading.
  • Public Signage: “MSGP operators must post a sign of permit coverage (except in the instance where other laws or local ordinances prohibit such signage) at a safe, publicly accessible location in close proximity to the facility, as other NPDES permittees are required to do. This notice must include basic information about the facility (e.g., the NPDES ID number), information that informs the public on how to request the facility’s Stormwater Pollution Prevention Plan (SWPPP), and how to contact the facility and EPA if stormwater pollution is observed in the stormwater discharge.
  • Good Housekeeping Measures: At least once weekly, employ housekeeping measures, such as “sweeping, vacuuming and other equivalent measures… in areas where cement, aggregate, kiln dust, fly ash or settled dust are being handled or processed and may be discharged in stormwater.” Concrete plants must also “prevent the exposure of fine granular (e.g., cement, fly ash, kiln dust) to stormwater, where practicable, by storing these materials in enclosed silos, hoppers, buildings or under other covering.”
  • Continued Total Suspended Solids (TSS) monitoring (there was concern this would be expanded to also require pH and chemical oxygen demand (COD) dubbed “universal benchmark monitoring”, both of which were NOT included for the concrete sector and which NRMCA opposed).
  • “Report Only” monitoring for polycyclic aromatic hydrocarbons (PAHs), or rather “stormwater discharges from paved surfaces that will be sealed or re-sealed with coal-tar sealcoat”.
  • NOT finalizing a proposed “Appendix Q”, which held a bevy of redundant and controversial “stormwater control measures (SCMs)” that NRMCA opposed. However, while not finalized for this permit, EPA has suggested they will continue to review the issue, and any questions about SCMs are covered in prior year’s MSGP guidance.
  • Major Storm Events: The new permit “requires that operators consider implementing enhanced stormwater control measures for facilities that could be impacted by major storm events, such as hurricanes, storm surge, and flood events. EPA is not requiring operators to implement additional controls if the operator determines such controls to be unnecessary, but EPA is requiring operators to consider the benefits of selecting and designing control measures that reduce risks to their industrial facility and the potential impact of pollutants in stormwater discharges caused by major storm events.
  • Additional Implementation Measures: “Both the proposed 2020 MSGP and this final 2021 MSGP maintain a three-level structure of advancement and responses triggered by benchmark exceedances and keep follow-up actions clear, timely, and proportional to exceedance frequency and duration.
  • NOT extending the 30-day wait period of NOIs. The proposal originally suggested stretching the wait period for 60 days, which NRMCA opposed, as many facilities may not be able to withhold discharges for 60 days.
  • NOT implementing an inspection only requirement for low risk facilities. NRMCA supported this provision, as it could have limited stormwater monitoring requirements for many concrete plants, and replaced them with simple periodic inspections for compliance.
  • All reporting must be submitted electronically, with few exceptions.


NRMCA submitted lengthy comments on the proposed MSGP back in May 2020. Numerous problematic additions were ultimately left out of the final permit, while other requirements were retained. NRMCA will continue to examine the permit for industry liabilities and burdensome compliance requirements.


To review the 2021 MSGP, accompanying factsheets and appendices please click here.