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1. What is an illicit discharge?

An illicit discharge is any discharge to a stormwater conveyance system (e.g., curb and gutter, street, swale, ditch, creek) that is not entirely composed of stormwater. Stormwater is defined as surface runoff free of pollutants to the maximum extent practicable.

2. What is meant by "maximum extent practicable"?

Maximum extent practicable (MEP) is a technology-based standard established by the Clean Water Act. MEP is generally the result of emphasizing pollution prevention and source control measures primarily (as the first line of defense) and in combination with treatment methods serving as a backup (additional line of defense). As an example, erosion control is a source control measure and silt fences and fiber rolls around the perimeter of the disrupted area is a treatment control measure. The use of a combination of erosion and sediment control measures are required to meet the MEP standard.

3. Do I need to prepare a Stormwater Pollution Prevention Plan (SWPPP)?

If your project disturbs one acre or more of land, you need to apply for coverage under the State Water Resources Control Board’s (SWRCB) National Pollutant Discharge Elimination System (NPDES) General Permit for Stormwater Associated with Construction Activity. The SWRCB also issues separate NPDES permits for some types of dewatering activities as well as linear construction projects, such as trenching for utilities. Refer to the SWRCB’s Stormwater Construction website for more information on NPDES permit requirements.

4. Does the SWRCB review and approve SWPPPs?

No. The SWRCB only looks at SWPPPs during inspections.