As the United States Environmental Protection Agency (USEPA) moves toward finalizing the 2026 Multi-Sector General Permit (MSGP), steel and related metal facilities should prepare for expanded monitoring obligations—most notably new per- and polyfluorinated alkyl substances (PFAS) sampling requirements—which may affect compliance complexity and cost.
The MSGP is the USEPA’s primary vehicle for regulating stormwater discharges from industrial facilities under the National Pollutant Discharge Elimination System (NPDES). Reissued approximately every five years, the MSGP establishes sector-specific monitoring requirements, benchmark thresholds, and stormwater pollution prevention plan (SWPPP) obligations for 29 industrial sectors. Sector F—Primary Metals covers iron, steel, and related metals manufacturing across seven subsectors: ferrous metal mills and foundries (F1), aluminum smelting (F2), copper and brass operations (F3), other nonferrous metals (F4), primary smelting and refining (F5), pipe and tube manufacturing (F6), and wire drawing (F7).
USEPA published the proposed 2026 MSGP in the Federal Register in December 2024 (Docket ID: EPA-HQ-OW-2024-0481), with a public comment period that closed in May 2025 after an extension. The 2026 MSGP is expected to be finalized sometime in 2026; upon issuance, all currently covered facilities will be required to submit new Notices of Intent (NOIs) to obtain coverage under the new permit.
Key Changes from the 2021 MSGP
PFAS Monitoring (New Requirement). The most significant new obligation for Sector F facilities is the addition of quarterly indicator monitoring for PFAS. Sector F is among 23 industrial sectors that USEPA has proposed to require stormwater sampling for 40 PFAS using USEPA Method 1633 (LC-MS/MS). Monitoring is required for the full permit term on a “report-only basis”—no benchmarks have been established yet. USEPA intends to use the collected data to inform future PFAS benchmark rulemaking. Facilities should anticipate substantially higher lab costs, as Method 1633 analysis is significantly more expensive than conventional stormwater parameters.
Benchmark Monitoring Adjustments. The 2026 MSGP proposes to modify how and when benchmark monitoring is conducted. Qualifying Sector F subsectors that showed exceedances of indicator parameters under the 2021 MSGP will be elevated from report-only indicator monitoring to full-benchmark monitoring for pH, total suspended solids (TSS), chemical oxygen demand (COD), and certain metals. Under the revised schedule, operators conduct quarterly benchmark sampling during the first three years of permit coverage (or 12 quarters). If all annual averages remain below benchmark thresholds, facilities may discontinue sampling; otherwise, monitoring continues for the permit term. This structure is designed to focus ongoing compliance effort on facilities with demonstrated water quality concerns.
Hardness-Based Metal Benchmarks. For copper, zinc, and lead, parameters particularly relevant to nonferrous metal subsectors, USEPA is proposing hardness-dependent benchmark values that vary based on the receiving water’s hardness. This means facilities discharging to softer waters will face lower (more stringent) benchmarks. Facilities will need to collect hardness data from receiving waters to determine the applicable benchmark tier.
Natural Background and Impaired Waters. The process for claiming a natural background exception has been tightened. Facilities must now submit analytical data and obtain USEPA approval before the exception applies. Additionally, all Sector F facilities discharging to waters listed as impaired on state 303(d) lists must conduct quarterly monitoring for the specific parameters driving the impairment. USEPA is seeking comment on whether this enhanced monitoring should be required for the full permit term.
Sector F — Proposed 2026 MSGP Monitoring Requirements
| Monitoring Type | Parameters | Subsectors Affected | Frequency and Notes |
| Benchmark Monitoring (Existing) | pH, TSS, COD; Total Copper | F5 (pH, TSS, COD), F2, F3, F4 (Copper) | Quarterly, years 1–3. May discontinue if annual average is below benchmark. |
| Benchmark Monitoring (New/Upgraded) | pH, TSS, COD (upgraded from indicator); sector-specific metals | Subsectors with 2021 MSGP indicator exceedances | Quarterly, years 1–3, and then discontinue if compliant; otherwise continue through permit term. |
| PFAS Indicator Monitoring (New) | 40 PFAS compounds per USEPA Method 1633 (LC-MS/MS), including PFOA, PFOS, PFHxS, PFNA, PFBS, and GenX | All Sector F subsectors (part of 23-sector requirement) | Quarterly, full permit term. Report only—no benchmarks established. Data inform future rulemaking. Expect significantly higher lab costs. |
| Polycyclic Aromatic Hydrocarbon (PAH) Indicator Monitoring (Continued) | 16 PAH compounds per 40 Code of Federal Regulations Part 423, Appendix A | All Sector F subsectors | Quarterly, report only. No benchmark thresholds. |
| Impaired Waters Monitoring (Enhanced) | Parameters specific to each 303(d)-listed waterbody impairment | All Sector F facilities discharging to impaired waters | Quarterly. USEPA seeking comment on full-term requirement. |
| Quarterly Visual Assessment (Continued) | Color, odor, clarity, floating solids, foam, sheen, staining | All Sector F subsectors | Each operational quarter. No lab analysis required. Records retained on-site. |
Compliance Considerations for Steel Facilities
Facilities currently covered under the 2021 MSGP should continue operating under existing permit conditions without interruption; no immediate action is required while the permit is administratively continued. The primary near-term planning task is to prepare for the transition once the 2026 MSGP is finalized. All currently covered facilities will need to submit a new NOI, and SWPPPs will require meaningful updates to address PFAS monitoring protocols, updated benchmark parameters, climate resilience language, and Additional Implementation Measures (AIM) reporting obligations.
Given the cost and complexity of PFAS sampling, facilities should begin now by assessing potential PFAS sources on-site—including aqueous film-forming foam (AFFF), surface treatments, coatings, and process lubricants—before the monitoring obligation takes effect. Steel facilities operating in states that model their general permits on USEPA’s MSGP—which represents the majority of states—should also monitor state permit renewal processes, as similar requirements are likely to be adopted at the state level over the next several years.
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To discuss any questions or concerns, please contact Bruce Martin or Katie Milk.
