On Jan. 15, the EPA issued the 2021 National Pollutant Discharge Elimination System (NPDES) Multi-Sector General Permit (MSGP). Though the finalized MSGP should take effect in March, the Biden administration has halted new regulations for review. If no changes are made, this finalized version incorporates a number of revisions for applicable facilities, including stormwater:

  • New features in the EPA’s NPDES eReporting Tool (NeT) and NeT-MSGP.
  • Quarterly ”report-only” indicator analytical monitoring for pH, Total Suspended Solids (TSS), and Chemical Oxygen Demand (COD) at certain facilities.
  • Biannual (twice per year) “report-only” indicator analytical monitoring for polycyclic aromatic hydrocarbons (PAHs) during the first and fourth years of permit coverage. (Applies to operators in all sectors with stormwater discharges from paved surfaces that will be sealed or re-sealed with coal-tar sealcoat.)
  • Quarterly benchmark and annual impaired waters monitoring in first and fourth years of permit (minimum).
  • Composite sampling may be used for indicator and benchmark monitoring instead of grab samples.
  • Updated benchmark concentrations for aluminum, copper, selenium, and cadmium, as well as suspended benchmark thresholds for magnesium and iron.
  • Tiered additional implementation measures (AIM) for benchmark exceedances.

The revised permit will apply to facilities in jurisdictions where EPA is the permitting authority: Idaho, Massachusetts, New Hampshire, New Mexico, Native American lands, Puerto Rico, the District of Columbia, and most U.S. territories and protectorates. On July 1, NPDES permitting authority for industrial stormwater will transfer to Idaho. It is likely that many of the remaining states will model their MSGP on the new federal permit.

The 2021 MSGP becomes effective on March 1 and will replace the 2015 MSGP.

“The 2021 MSGP contains some significant changes, especially related to monitoring and implementation of additional control measures. We can help you navigate these changes to be in compliance with the new permit from Day 1.”

Elizabeth Wilson, Principal Scientist

About the experts

Elizabeth Wilson is Principal Scientist, Environmental Compliance, for Brown and Caldwell. She is based in New Hampshire, and has 16 years of environmental consulting and industry experience.

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