The U.S. Environmental Protection Agency (EPA) is seeking public comment on its proposed 2020 National Pollutant Discharge Elimination System (NPDES) Multi-Sector General Permit (MSGP) for stormwater discharges. This proposed permit — which looks to improve methods to prevent such discharges — is associated with industrial activity in areas where the EPA is the NPDES permitting authority, including Idaho, Massachusetts, New Hampshire, New Mexico, District of Columbia, U.S. territories, and federal and tribal lands.

If approved, it would replace the EPA’s 2015 MSGP. States that have the authority to run their own programs would consider the finalized 2020 MSGP as a model for their state-specific permit requirements. Proposed changes primarily relate to site eligibility and benchmark monitoring requirements.

Eligibility Updates

The proposed 2020 MSGP updated requirements would apply to all regions and would require facilities that use coal-tar sealcoat — which, in turn, discharges polycyclic aromatic hydrocarbons (PAHs) into stormwater runoff — to eliminate this discharge for coverage approval under the MSGP. Operators who wish to continue use of coal-tar sealcoat may apply for an individual permit.

Eligibility updates would affect sites that discharge to federal Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA or Superfund sites). Currently, the only facilities that must report stormwater discharges onto CERCLA sites are those listed in EPA Region 10 (Pacific Northwest).

Benchmark Monitoring

The bulk of the proposed updates to the MSGP pertain to benchmark monitoring. EPA is proposing universal quarterly benchmark monitoring for pH, total suspended solids (TSS) and chemical oxygen demand (COD) over the entire permit term.

The current 2015 permit does not require all sectors to perform benchmark monitoring. If passed, the 2020 permit would apply to all facilities in all sectors. The thresholds for selenium, arsenic, cadmium, magnesium, iron and copper would be modified based on updated toxicity information.

Additionally, Sector I (Oil and Gas Extraction); Sector P (Land Transportation and Warehousing); and Sector R (Ship and Boat Building and Repair Yards), which did not previously require any benchmark sampling, would require benchmark monitoring under the proposed permit. Benchmark monitoring exceedances would trigger new tiered “Additional Implementation Measures” (AIM), with three-tiered AIM levels dictating increasingly robust control measures, based on the magnitude of the benchmark threshold exceedance.

These proposed changes to benchmark monitoring have the potential to affect businesses in the identified sectors, namely Sector P (Land Transportation and Monitoring). Facilities in this sector typically have designated areas for vehicle and equipment storage, cleaning and maintenance, fueling, material storage, and locomotive sanding areas. Sector P would still be permitted to use on-site chemicals such as solvents, diesel fuel, gasoline, hydraulic fluids, antifreeze and transmission fluids.

However, the EPA proposes that facilities in Sector P have benchmark monitoring for lead (hardness dependent for freshwater or 210 ug/L for saltwater) and mercury (freshwater 1.4 ug/L or saltwater 1.8 ug/L) in addition to the proposed universal quarterly benchmark monitoring for pH, TSS and COD.

Under the proposed 2020 MSGP, these facilities also would require updates to their Stormwater Pollution Prevention Plans (SWPPPs) as well as development of sampling plans to comply with the new benchmark monitoring requirements.

The EPA is accepting comments on the proposed 2020 MSGP through May 31, 2020. Comments must be submitted on for docket ID #EPA-HQ-OW-2019-0372.


Industry professionals, those with extensive knowledge in NPDES permitting and SWPPPs, work hand in hand with facility owners and operators to meet stormwater regulatory requirements.

Learn More

With more than 15 years of consulting experience, Christine Mayo, a senior environmental specialist at Burns & McDonnell and certified lead auditor, specializes in multimedia environmental compliance auditing and permitting, ISO 14001 environmental management systems, and industrial hygiene and safety. Her multimedia environmental compliance experience includes stormwater planning, spill prevention planning, hazardous materials and waste, and air quality.