CWA Section 402: EPA Industrial Stormwater

Regulatory citation: Clean Water Act Section 402; National Pollutant Discharge Elimination System (NPDES) stormwater program

What Is EPA's Industrial Stormwater Program?

Under Clean Water Act Section 402, the National Pollutant Discharge Elimination System (NPDES) program requires permits for stormwater discharges from certain industrial activities and construction sites. EPA issues the Multi-Sector General Permit (MSGP) for industrial facilities in areas where it is the permitting authority, while most states issue their own general permits.

Why Stormwater Matters

Rain and snowmelt that run over industrial sites can pick up oil, metals, chemicals and sediment and carry them into rivers, lakes and streams. Stormwater permits aim to keep pollutants from being exposed to rainfall in the first place.

Core Requirements

1. Determine Whether You Need Coverage

Industrial stormwater permits apply to specific categories of industrial activity, identified largely by industry code, such as manufacturing, transportation facilities with vehicle maintenance, recycling facilities and landfills. Construction activities disturbing one acre or more generally need construction stormwater permit coverage.

2. Obtain Permit Coverage

Facilities typically obtain coverage by submitting a notice of intent under a general permit issued by EPA or the state.

3. Prepare a Stormwater Pollution Prevention Plan (SWPPP)

The SWPPP identifies potential pollutant sources and describes control measures, such as good housekeeping, covering materials, spill prevention and structural controls.

4. Inspect and Monitor

Permits require routine facility inspections and, for many sectors, benchmark or compliance monitoring of stormwater discharges.

5. Take Corrective Action

When inspections or monitoring show problems, facilities must investigate and correct control measures within set timeframes.

6. Consider No Exposure Certification

Facilities where industrial materials and activities are fully protected from stormwater may qualify for a conditional no exposure exclusion instead of full permit requirements.

Common Compliance Approaches

Map Drainage and Outfalls

Know where stormwater flows and where it leaves your site.

Cover and Contain

Move storage indoors or under cover and keep dumpsters closed to prevent exposure.

Train Your Stormwater Team

Staff responsible for inspections and sampling need to understand permit requirements and deadlines.

Example: Industrial Stormwater Compliance in Practice

A truck maintenance facility is covered by its state's industrial stormwater general permit. Its SWPPP identifies used oil storage, vehicle washing and scrap metal piles as pollutant sources. The facility builds a roof over the oil storage area, routes wash water to the sanitary sewer with approval, conducts quarterly inspections and benchmark sampling, and updates its SWPPP after sampling shows elevated zinc.

Related regulations: EPA SPCC Rule, EPA Hazardous Waste Generators, EPA General Duty Clause.

Note: This summary reflects federal EPA requirements. Many states run authorized programs with additional or stricter rules. Always check the current regulation text and your state environmental agency's requirements.

Frequently Asked Questions

What is a SWPPP?

A Stormwater Pollution Prevention Plan (SWPPP) is a site-specific plan that identifies potential sources of stormwater pollution at a facility and describes the practices and controls used to reduce pollutants in stormwater discharges.

Who needs an industrial stormwater permit?

Facilities in specific industrial categories, defined largely by industry code, that discharge stormwater to surface waters or separate storm sewer systems generally need NPDES permit coverage, unless they qualify for a no exposure exclusion.

Is stormwater permitting run by EPA or the states?

Most states are authorized to run their own NPDES stormwater programs and issue their own general permits. EPA issues permits directly in a small number of states, territories and on certain tribal lands.