Illicit Discharge Detection: What Ohio Facilities and Municipalities Need to Know

What Is an Illicit Discharge?

An illicit discharge is any discharge to a storm drain system that is not composed entirely of stormwater. Under the Clean Water Act, anything other than rainwater that enters a storm drain — and ultimately flows untreated to local waterways — is considered an illicit discharge and is prohibited by federal law.

Common examples include:

• Sanitary sewer connections — Sewage piped into the storm system through cross-connections
• Industrial process water — Wash water, coolant, or chemicals discharged to parking lot drains
• Vehicle washing — Soap, oil, and grime from washing vehicles or equipment on pavement
• Improper dumping — Paint, solvents, used oil, or other chemicals poured into storm drains
• Failing septic systems — Leaking septic effluent reaching storm drain infrastructure
• Swimming pool discharges — Chlorinated pool water drained to storm systems

The only things that should go into a storm drain are rainwater and snowmelt. Everything else is an illicit discharge — intentional or not.

Why IDDE Matters for Ohio Municipalities

If your municipality operates under an MS4 permit, Illicit Discharge Detection and Elimination (IDDE) is one of the six required minimum control measures under Ohio EPA's general permit OHQ000004. You must:

1. Develop a storm sewer system map — Document all outfalls, pipes, and connections in your system
2. Adopt an illicit discharge ordinance — Pass local legislation prohibiting non-stormwater discharges
3. Implement a detection program — Systematically screen outfalls and investigate potential illicit discharges
4. Conduct dry weather screening — Inspect outfalls during dry weather; any flow detected could be illicit
5. Track and eliminate sources — Investigate, trace, and eliminate every confirmed illicit discharge
6. Train municipal staff — Public works, code enforcement, and field crews must recognize and report illicit discharges

Ohio EPA audits are increasingly focused on IDDE programs. If you can't demonstrate an active detection and elimination effort, you risk enforcement action.

How Illicit Discharges Are Detected

There are several proven methods for identifying illicit discharges in storm drain systems:

Dry Weather Outfall Screening

The most common method. During a period of at least 72 hours without rainfall, crews inspect every storm drain outfall. Any flow observed during dry weather is suspicious and triggers an investigation.

Field teams check for:

• Visual indicators — Color, clarity, sheen, foam, or floating material
• Odor — Sewage, chemical, petroleum, or rotten egg smells
• Field testing — pH, ammonia, chlorine, surfactants, and temperature are tested on-site

CCTV Pipe Inspection

CCTV camera inspections allow crews to travel upstream from an outfall and visually identify where an illicit connection enters the storm system. This is the most definitive method for pinpointing cross-connections.

Dye and Smoke Testing

Non-toxic dye is flushed into suspected source connections (toilets, floor drains, sinks) and monitored at storm drain outfalls. Smoke testing involves pressurizing the storm system with non-toxic smoke; if smoke appears inside a building, that building has a connection to the storm drain.

Water Quality Sampling

Laboratory analysis of storm drain flow can identify the type of pollutant and help narrow the source. Common parameters include E. coli, ammonia, surfactants (from soaps), and optical brighteners (from laundry discharge).

What Industrial and Commercial Facilities Need to Know

IDDE isn't just a municipal responsibility. If you own or operate a commercial or industrial facility, you're responsible for ensuring that nothing from your property enters the storm drain system except stormwater.

Common violations we see at Ohio commercial properties:

• Pressure washing runoff — Building washing, sidewalk cleaning, or equipment washing that flows to storm drains without treatment
• Dumpster leachate — Liquid waste from dumpsters draining to parking lot catch basins
• Loading dock wash-down — Cleaning spills on loading docks that flow to storm drains
• HVAC condensate with chemicals — Treated cooling water discharged to the storm system
• Landscape chemical runoff — Fertilizer and pesticide applications near storm drain inlets
• Floor drain cross-connections — Indoor floor drains mistakenly connected to storm rather than sanitary sewer

If your municipality identifies your property as the source of an illicit discharge, you are responsible for correcting it at your own expense. Penalties under the Clean Water Act can reach $25,000 per day per violation.

Building an Effective IDDE Program

For municipalities building or improving their IDDE programs, here's a framework based on Ohio EPA expectations and our field experience:

Phase 1: Mapping (Year 1)

• Map all outfalls, major junction points, and interconnections in your storm system
• GIS-based mapping is preferred; Ohio EPA expects digital, updatable records
• Include pipe material, size, direction of flow, and receiving waterway

Phase 2: Priority Screening (Year 1-2)

• Conduct dry weather screening at all outfalls, starting with priority areas (industrial zones, older neighborhoods, known problem areas)
• Document all findings with photos, field measurements, and GPS coordinates
• Flag any outfall with dry weather flow for investigation

Phase 3: Investigation and Elimination (Ongoing)

• Trace each identified discharge upstream using CCTV inspection, dye testing, or smoke testing
• Issue notices of violation to property owners with illicit connections
• Verify elimination through follow-up inspection
• Document the entire process for annual MS4 reporting

Common IDDE Program Failures (What Ohio EPA Looks For)

During MS4 audits, Ohio EPA frequently cites these IDDE deficiencies:

• No outfall map — The program exists on paper but the municipality can't show where their outfalls are
• No dry weather screening records — The ordinance was adopted but no actual screening has been performed
• No investigation follow-through — Discharges were identified but never traced or eliminated
• Inadequate documentation — Screening was performed but records are incomplete or missing
• No training program — Municipal staff weren't trained to recognize or report illicit discharges

How EnviroFlow USA Supports IDDE Programs

We provide the field services that municipalities and facilities need to run effective IDDE programs:

• Dry weather outfall screening — Systematic inspection with field testing and photographic documentation
• CCTV pipeline investigation — Camera inspection to trace illicit connections to their source
• Dye and smoke testing — Non-invasive source identification for cross-connections
• Catch basin cleaning — Remove accumulated pollutants before they discharge downstream
• IDDE program development — Help municipalities build programs that meet Ohio EPA requirements
• Compliance documentation — Complete reporting packages for MS4 annual reports

Call us at (440) 290-1550 or contact us to discuss your IDDE needs.