Understanding industrial stormwater risks and what EPA’s proposed 2026 MSGP could mean for facility environmental management.
Stormwater is part of every industrial facility. The U.S. Environmental Protection Agency (EPA) defines industrial stormwater as stormwater runoff from industrial activities. This includes runoff from rain, snowmelt, surface runoff, and drainage that may come into contact with activities at a facility (40 CFR 122.26(b)(13)–(14)).
The key concern arises when that water comes into contact with industrial materials or activities.
Outdoor storage areas, loading and unloading zones, waste containers, equipment, maintenance activities, raw materials, dust, oils, or chemicals may be exposed to rain or snowmelt. Stormwater can pick up pollutants and carry them directly to a waterbody or indirectly through a storm drainage system.
That is why stormwater management is much more than a rainy-day activity. It is an operational issue.
Follow the Water
A simple way to understand industrial stormwater risk is to follow the path of the water:
Rainfall → Industrial Exposure → Runoff → Drainage System → Discharge Point → Receiving Water
The most important part of this sequence may be industrial exposure itself.
Consider a loading area where small product spills occur. During dry weather, the situation may seem like nothing more than a housekeeping issue. Then it rains.
Water flows across the pavement, comes into contact with the material, reaches a catch basin, and continues through the storm drainage system. What appeared to be only a housekeeping issue can now become a stormwater issue.
The same principle applies to leaking equipment, unprotected waste containers, outdoor storage of chemicals or raw materials, accumulated dust or debris, vehicle maintenance areas, scrap materials, and other industrial activities.
The key question is not simply where stormwater goes, but what it can come into contact with before it gets there.
Your SWPPP Should Reflect Actual Facility Conditions
For facilities subject to industrial stormwater permitting requirements, the Stormwater Pollution Prevention Plan (SWPPP) plays an important role in connecting regulatory requirements with actual operating conditions.
However, a SWPPP provides value only when it reflects what is actually happening at the facility.
Facilities change. Equipment is relocated. Production increases. New chemicals are introduced. Storage areas are modified. Waste streams change. Outdoor activities expand. Even drainage patterns can change when infrastructure is modified.
If stormwater management does not evolve with these changes, a gap can develop between the conditions described in the plan and the conditions that actually exist at the facility.
EPA regulates different industrial activities through the Multi-Sector General Permit (MSGP), which covers 29 industrial sectors and includes sector-specific information and requirements, including typical pollutants and stormwater control measures.
That is why an effective stormwater program should connect the SWPPP with day-to-day operations. Inspections, employee awareness, good housekeeping, preventive maintenance, spill prevention and response, material management, stormwater controls, monitoring, and corrective actions work together to help prevent materials used or generated by the operation from becoming pollutants carried by stormwater.
The Proposed 2026 MSGP: What Should Facilities Be Watching?
Industrial stormwater requirements are also evolving.
EPA’s 2021 MSGP expired on February 28, 2026. Because EPA did not issue a replacement permit before that date, the 2021 MSGP is currently administratively continued for facilities that had coverage before the permit expired.
This means those facilities must continue complying with applicable permit conditions, including relevant monitoring and reporting requirements, while EPA completes the new permit.
EPA has proposed a new 2026 MSGP, which would replace the 2021 permit once finalized. The proposal applies to industrial stormwater discharges in areas where EPA serves as the permitting authority under the National Pollutant Discharge Elimination System (NPDES) (Federal Register, December 13, 2024).
Several proposed changes are worth watching closely.
PFAS Enters the Industrial Stormwater Conversation
One of the most notable proposed changes is the addition of indicator monitoring for Per- and Polyfluoroalkyl Substances (PFAS), a broad category of fluorinated chemicals.
Under the proposed 2026 MSGP, operators in certain industrial sectors would conduct quarterly analytical monitoring for 40 PFAS compounds using EPA Method 1633.
The proposed monitoring is indicator monitoring for reporting purposes. The proposal does not establish a benchmark for these PFAS results, nor would an analytical result by itself automatically trigger the permit’s follow-up actions (Proposed 2026 MSGP Fact Sheet).
Could PFAS-containing materials or activities at our facility be exposed to stormwater?
Answering that question may require looking far beyond the storm drain. Facilities may need to understand their raw materials, products, processing aids, waste streams, storage areas, and other industrial activities that could potentially contribute PFAS to runoff.
Monitoring Continues to Evolve
The proposal includes changes to benchmark monitoring requirements and other types of monitoring.
This monitoring provides information on concentrations of certain pollutants and helps evaluate the effectiveness of implemented control measures. The proposed 2026 MSGP draws on data and experience from previous permits and proposes changes for different sectors and pollutants.
Sampling should not simply generate laboratory results. The data should help explain what is actually happening at the facility.
An unexpected result can be a reason to investigate drainage areas, material exposure, housekeeping practices, control measures, operational changes, or potential pollutant sources.
In this way, monitoring becomes more than a compliance obligation; it can also serve as a tool for evaluating the effectiveness of stormwater management.
Preparing for More Resilient Stormwater Controls
EPA’s proposal also addresses consideration of enhancements to stormwater control measures for major storm events.
The proposed permit would have operators consider the benefits of selecting and designing controls that reduce risks to industrial facilities and the potential impact of pollutants in stormwater during significant events.
This adds another dimension to stormwater management.
How might our stormwater system perform under more intense rainfall or flooding conditions?
What Can Facilities Do Now?
Although the 2026 MSGP remains a proposal and its new requirements should not yet be treated as current obligations, facilities can use this time to evaluate how well they understand and manage their stormwater today.
A good starting point is to walk the facility and follow the path of the water. This helps identify which materials and activities are exposed to rain, where runoff flows, which drains and catch basins receive water from each area, and where the water ultimately leaves the site. Drainage maps and the SWPPP should reflect these actual conditions and be kept current as operations, infrastructure, or storage areas change.
The review should also pay attention to conditions that may appear minor during day-to-day operations: exposed containers, small leaks, pavement staining, accumulated sediment or debris, outdoor storage, and loading or unloading areas. These conditions can become sources of pollution when they come into contact with rainfall.
Historical inspection and monitoring results can also provide valuable information. Rather than reviewing each result in isolation, looking at trends, unexpected values, or recurring issues can help determine whether control measures are working or whether a pollutant source requires further investigation.
In light of the proposed 2026 MSGP, this is also an appropriate time to begin understanding whether PFAS may be present in raw materials, products, processing aids, wastes, or other facility activities that could potentially be exposed to stormwater. This does not mean treating a proposed requirement as if it were already in effect; it means improving operational knowledge and being better prepared for potential regulatory changes.
Ultimately, being prepared does not mean waiting for a new permit before taking action. It means knowing the site, understanding the path of the water, keeping the SWPPP current, evaluating available information, and verifying that control measures match actual operating conditions.
An Important Distinction: EPA MSGP vs. State Requirements
The federal MSGP should not be interpreted as the industrial stormwater permit that automatically applies to every facility in the United States.
EPA has authorized many states to administer their own NPDES programs. In fact, most industrial facilities obtain NPDES permit coverage through their state. EPA remains the permitting authority in certain jurisdictions.
For this reason, each facility should first identify the applicable permitting authority and the requirements for its specific location before determining its obligations.
Stormwater Management Starts Before the Storm
Industrial stormwater management is sometimes viewed as a specialized environmental compliance activity.
In practice, it depends heavily on everyday operational decisions: where materials are stored, how waste is managed, whether leaks are identified and corrected, how loading and unloading areas are maintained, whether employees recognize conditions that may create stormwater exposure, whether facility changes are incorporated into the SWPPP, and whether monitoring results are used to investigate what is actually happening onsite.
The proposed 2026 MSGP provides an additional reason for facilities to review these systems, particularly in light of the changes EPA is considering related to PFAS, monitoring, and stormwater control measures.
Effective stormwater management does not begin when it rains. It begins with understanding what the rain can come into contact with.
A facility that understands this pathway is better positioned to identify risks, maintain effective controls, respond to regulatory changes, and prevent pollutants from leaving the site through stormwater.
Abbreviations Used
EPA: U.S. Environmental Protection Agency
MSGP: Multi-Sector General Permit
SWPPP: Stormwater Pollution Prevention Plan
NPDES: National Pollutant Discharge Elimination System
PFAS: Per- and Polyfluoroalkyl Substances
Sources
- U.S. EPA. Stormwater Discharges from Industrial Activities.
- Code of Federal Regulations. 40 CFR 122.26 — Storm water discharges.
- U.S. EPA. Industrial Stormwater Fact Sheet Series.
- U.S. EPA. Administrative Continuance of EPA’s 2021 MSGP.
- U.S. EPA. Stormwater Discharges from Industrial Activities — EPA’s Proposed 2026 MSGP.
- U.S. EPA. Proposed 2026 MSGP Fact Sheet (December 2024).
- Federal Register. NPDES 2026 Issuance of the Multi-Sector General Permit for Stormwater Discharges Associated With Industrial Activity (89 FR, December 13, 2024).
