• Most stormwater discharges are considered point sources and require coverage by a permit under NPDES.
• The NPDES stormwater permitting program is organized according to the three types of regulated stormwater discharges.

Stormwater discharges are generated by rainwater and snowmelt runoff from land and impervious areas such as paved streets, parking lots, and building rooftops. This runoff often contains pollutants in quantities that could adversely affect water quality.

Most stormwater discharges are considered point sources and require coverage by a permit under the National Pollutant Discharge Elimination System (NPDES). The primary method to control stormwater discharges is through the use of best management practices. The NPDES stormwater permitting program is organized according to the three types of regulated stormwater discharges:

• Industrial,
• Construction, and
• Municipal separate storm sewer systems (MS4s).

Cited under 40 CFR 122.26, major requirements related to stormwater include:

For industrial facilities:

• Determine if the facility’s Standard Industrial Classification (SIC) code or industrial activity is subject to NPDES stormwater permitting.
• Determine if the facility is in a state that runs its own NPDES stormwater permitting program, or if the facility must apply for a Multi-Sector General Permit (MSGP).
• Test for the contaminants that are found in the facility’s stormwater/snowmelt discharges.
• Apply for the proper permit (general, specific, MSGP, construction, construction MSGP, or other).
• Comply with the terms and conditions listed in the permit.

For construction activities:

• Determine if construction activities will disturb one or more acres of land or are part of a larger construction project that will disturb five or more acres of land.
• Determine if the facility is eligible for a Construction General Permit.
• Apply for a stormwater construction permit.
• Comply with the terms and conditions in the permit.