Ohio's MS4 Permit Is Expiring — Are You Ready?
Ohio EPA's current Small MS4 General Permit (OHQ000004) expires March 31, 2026, and a new permit is expected in summer 2026. Whether you're renewing your permit or applying for the first time, now is the time to ensure your stormwater management program meets all requirements.
At EnviroFlow USA, we help municipalities across Northeast Ohio build and maintain MS4-compliant stormwater programs. Here's what you need to know.
What Is an MS4 Permit?
MS4 stands for Municipal Separate Storm Sewer System. If your municipality operates a storm sewer system that's separate from the sanitary sewer system (which is most Ohio communities), and you're located in an urbanized area, you're required to hold an MS4 permit.
The permit requires you to develop and implement a Stormwater Management Program (SWMP) that addresses six areas called Minimum Control Measures (MCMs).
The Six Minimum Control Measures
MCM 1: Public Education and Outreach
You must educate residents and businesses about stormwater pollution and what they can do to prevent it. This includes distributing educational materials, hosting workshops, and maintaining a stormwater-focused section on your municipal website.
MCM 2: Public Involvement and Participation
Citizens must have opportunities to participate in your stormwater program. This can include public meetings, volunteer stream cleanups, storm drain marking programs, and citizen advisory committees.
MCM 3: Illicit Discharge Detection and Elimination (IDDE)
You need a program to find and stop illicit discharges — any non-stormwater flow entering your storm sewer system. This requires mapping your system, conducting dry-weather screening, and having enforcement authority to stop violations.
MCM 4: Construction Site Runoff Control
Your municipality must have an ordinance requiring erosion and sediment controls on construction sites, plus an inspection and enforcement program to ensure compliance.
MCM 5: Post-Construction Stormwater Management
New development and redevelopment must include permanent stormwater controls that manage runoff after construction is complete. You need an ordinance and a long-term inspection program.
MCM 6: Pollution Prevention and Good Housekeeping
This is where physical infrastructure maintenance comes in. Your municipality must maintain its own stormwater facilities, including:
- Regular catch basin cleaning
- Storm drain inspection and maintenance
- Street sweeping programs
- Stormwater system repairs
- Staff training on pollution prevention
Common Compliance Gaps We See
After working with dozens of Ohio municipalities, these are the gaps we see most often:
- Documentation — The work is being done, but inspection records, cleaning logs, and maintenance documentation are incomplete or disorganized
- Catch basin maintenance — Many municipalities clean some basins but don't have a systematic program covering the entire system
- IDDE program — Outfall screening is sporadic or the system map is outdated
- Staff training — MCM 6 requires documented training for municipal employees on stormwater practices
- Annual reporting — Reports are submitted late, are incomplete, or don't demonstrate measurable progress
How EnviroFlow USA Supports Municipal MS4 Programs
We serve as the field services partner for municipalities across Cuyahoga, Lake, Geauga, Lorain, Medina, Portage, and Summit counties. Our MS4 support services include:
- Systematic catch basin cleaning with GPS documentation and photo records
- CCTV sewer inspections coded to NASSCO PACP standards
- Stormwater infrastructure assessment and condition reporting
- Illicit discharge screening at outfalls and key locations
- Compliance documentation formatted for Ohio EPA reporting requirements
Need help getting your MS4 program audit-ready? Call (440) 290-1550.