Industrial Stormwater Pollution: How It's Regulated and Tracked
When rain falls on an industrial facility, it picks up pollutants — oils, metals, chemicals, sediment — from surfaces, equipment, and storage areas and carries them into storm drains, nearby streams, or directly to surface waters. This "industrial stormwater" is regulated under the Clean Water Act\'s NPDES program, but it receives far less public attention than direct process discharges — partly because it\'s harder to measure and partly because violations are less visible than, say, a pipe discharging into a river.
The Multi-Sector General Permit
Most industrial facilities managing stormwater do so under EPA\'s Multi-Sector General Permit (MSGP), a standardized permit that covers 30 industrial sectors. The MSGP requires facilities to develop and implement a Stormwater Pollution Prevention Plan (SWPPP) that identifies pollution sources, implements Best Management Practices (BMPs), and establishes monitoring and inspection protocols. It doesn\'t typically set numeric discharge limits for pollutants — instead it focuses on management practices and visual monitoring.
Benchmark Monitoring and Exceedances
MSGP requires "benchmark monitoring" — quarterly sampling of stormwater discharges for pollutants of concern for the facility\'s sector. Benchmark values are not effluent limits; they are indicators of whether BMPs are working. Exceedances trigger a requirement to review and improve BMPs, not automatic violations. But repeated exceedances without corrective action can lead to enforcement. Stormwater violations from benchmark monitoring appear in ECHO less consistently than process discharge violations.
Connection to TRI Data
Stormwater can be a pathway for chemicals stored at industrial facilities to reach surface waters. Some TRI releases categorized as "surface water" may reflect stormwater pathways rather than direct pipe discharges. When a facility reports significant TRI releases to surface water from land-based activities, stormwater is often the mechanism. Browse facilities with TRI water releases at the chemical index filtered for water release categories, or explore facilities in your state at the state browser.
Phase II Stormwater Program
Smaller industrial facilities and municipal separate storm sewer systems (MS4s) — including many suburban storm drain systems — are regulated under the Phase II NPDES stormwater program, which has less stringent requirements than Phase I. Compliance with Phase II stormwater requirements is tracked in ECHO, though coverage is less comprehensive than for major point sources. Browse facilities and their water compliance status at the facility database.