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Proposed 2026 EPA MSGP Changes — What Industrial Facilities Should Expect

EPA published the proposed 2026 Multi-Sector General Permit on December 13, 2024 (Federal Register docket EPA-HQ-OW-2024-0481). The comment period closed May 19, 2025 and the permit is in final review. Five confirmed changes will reshape industrial stormwater compliance: report-only PFAS monitoring across 23 sectors, quarterly benchmark monitoring for the first three years, climate-resilience documentation, expanded impaired-waters monitoring, and a new enforceable visual discharge standard.

Five Confirmed Changes in the Proposed 2026 MSGP

PFAS Monitoring — New, 23 Sectors
The most significant new requirement. Sectors A, B, C, D, F, I, K, L, M, N, P, R, S, T, U, V, W, X, Y, Z, AA, AB, and AC must conduct report-only PFAS monitoring using EPA Method 1633 for 40 PFAS compounds across the full five-year permit term. No numeric benchmarks are established yet — EPA is collecting baseline data to inform future rulemaking. "Report-only" does not mean results can be ignored; values above health advisory levels will draw scrutiny.
Benchmark Monitoring Frequency Increase
The 2021 MSGP required quarterly benchmark monitoring only in permit years 1 and 4 (semi-annually otherwise). The proposed 2026 MSGP requires quarterly monitoring for the first three consecutive years (or until 12 quarters of data are collected) — a substantial increase in sampling and lab cost for facilities with multiple outfalls. New benchmark parameters are proposed for ammonia/nitrate/nitrite at vehicle maintenance areas (subsector I1), and pH/TSS/COD and metals are upgraded from indicator to benchmark status across several subsectors.
Climate Resilience Documentation
Operators must document how stormwater control measures are designed to withstand projected future weather conditions: consult FEMA Flood Maps, NOAA precipitation frequency data, or USGS stream gauge data to assess flood vulnerability; evaluate whether increased storm frequency or intensity affects BMP effectiveness; adjust maintenance schedules; and record all of it in the SWPPP.
Impaired Waters Monitoring Expansion
Quarterly monitoring will be required for all relevant pollutants when discharging to waters on the 303(d) impaired waters list — regardless of whether a TMDL has been established.
New Visual Discharge Standard
Discharges must not contain or result in observable floating solids, scum, sheen, foam, or discoloration. This adds a specific enforceable visual standard that did not exist in the 2021 MSGP.

Budget Impact

EPA's regulatory analysis for the proposed permit estimates incremental compliance cost at approximately $4,670 per facility per year, driven primarily by EPA Method 1633 PFAS analysis, the increased benchmark sampling frequency, and climate-resilience documentation. Facilities with multiple outfalls or in PFAS-monitored sectors should plan for the higher end of that range.

Cost-data disclosure. The figure above is EPA's own published per-facility estimate from the proposed 2026 MSGP regulatory analysis, not an Inspections Plus price. It is illustrative only and does not constitute a price quote or binding offer. Actual compliance cost depends on your sector, outfall count, monitoring obligations, and the scope agreed in a written Service Agreement. See Terms §2.

Continuance Is Not a Compliance HolidayUntil the 2026 MSGP issues, the 2021 permit's requirements remain fully in force under administrative continuance. The transition window is a higher-risk enforcement period, not a lower one — EPA Region 6 uses inspection sweeps during permit transitions to identify non-compliant facilities. Use this time to update your SWPPP and prepare for the new requirements rather than scaling back.

How to Prepare

Identify your MSGP sector(s) and confirm whether PFAS monitoring will apply
Get baseline lab quotes for EPA Method 1633 (40 PFAS compounds) at each monitored outfall
Map your outfalls and re-cost benchmark sampling at quarterly frequency for three years
Pull FEMA, NOAA, and USGS data for your site to begin climate-resilience documentation
Check whether any receiving water is on New Mexico's 303(d) impaired waters list
Schedule a SWPPP update so the document is current before the new permit's NOI window opens

Official EPA Sources

MSGP industrial permit overview →Benchmark monitoring detail →Industrial SWPPP guide →

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Frequently Asked Questions

When does the 2026 MSGP take effect?
EPA published the proposed 2026 MSGP on December 13, 2024, and the public comment period closed May 19, 2025. As of this writing the permit is in final review and EPA has not published a final effective date. The 2021 MSGP remains in effect under administrative continuance until the new permit issues. When it does, there is typically a defined submission window — usually around 90 days — to file a new Notice of Intent under the new permit.
Will my facility have to monitor for PFAS?
If your facility falls within one of the 23 sectors named in the proposal (A, B, C, D, F, I, K, L, M, N, P, R, S, T, U, V, W, X, Y, Z, AA, AB, AC), then yes — report-only PFAS monitoring via EPA Method 1633 for 40 compounds would be required for the full permit term once the 2026 MSGP is final. There are no numeric PFAS benchmarks yet; the data is collected to inform future rulemaking.
How much will the new requirements cost?
EPA's own regulatory analysis for the proposed 2026 MSGP estimates incremental compliance cost at roughly $4,670 per facility per year, driven primarily by Method 1633 PFAS lab analysis, the increased benchmark sampling frequency, and climate-resilience documentation. Actual cost depends on your sector, number of outfalls, and existing program — see the cost-data disclosure below.