The Stormwater Pollution Prevention Plan (SWPPP) is required under the National Pollutant Discharge Elimination System (NPDES) for industrial facilities and construction sites that discharge stormwater. While routine BMP inspections verify that individual controls are functioning, a program audit evaluates whether your overall stormwater program meets permit requirements including plan adequacy, monitoring compliance, BMP effectiveness, employee training, and recordkeeping. Many NPDES permits require annual comprehensive site compliance evaluations in addition to routine inspections.
Free Stormwater/SWPPP Program Audit Checklist
Download our Word document checklist for stormwater/swppp program audits.
Download Checklist (.docx)Regulatory Requirements
Clean Water Act — NPDES Program
The Clean Water Act Section 402 establishes the NPDES permit program. Industrial facilities covered under the Multi-Sector General Permit (MSGP) or individual permits must develop and implement a SWPPP, conduct monitoring, perform inspections, and submit required reports. Permits are issued by EPA or delegated state agencies.
EPA Multi-Sector General Permit (MSGP)
The MSGP covers stormwater discharges from industrial activities in 29 industry sectors. Requirements include a written SWPPP, routine facility inspections, quarterly visual monitoring, benchmark and effluent limit monitoring (where applicable), annual comprehensive site evaluations, and corrective action procedures.
State NPDES Programs
Most states have delegated NPDES authority and issue their own industrial stormwater general permits. State permits may have additional or more stringent requirements than the federal MSGP. Always verify your specific state permit requirements when conducting program audits.
SWPPP Documentation
| Audit Item | Expected Finding / What to Evaluate |
|---|---|
| Plan availability | Current SWPPP is maintained on-site and available for review by regulatory inspectors. Plan is accessible to all facility personnel involved in stormwater management. Electronic or hard copy is available at all times. |
| Permit coverage | Facility has active NPDES permit coverage (general or individual permit). Notice of Intent (NOI) was submitted and acknowledged. Permit number is documented. Permit renewal dates are tracked. |
| Site map | SWPPP includes a current site map showing buildings, paved areas, drainage patterns, outfall locations, sampling points, structural BMPs, and receiving waters. Map reflects current facility layout and any recent modifications. |
| Pollution sources | All potential sources of stormwater pollution are identified and documented including material storage areas, loading/unloading areas, outdoor process areas, waste management areas, and vehicle maintenance areas. |
| BMP selection | BMPs are identified for each potential pollution source. Both structural and non-structural BMPs are documented. BMPs are appropriate for the identified pollutant sources and site conditions. |
Monitoring and Sampling
| Audit Item | Expected Finding / What to Evaluate |
|---|---|
| Quarterly visual monitoring | Visual monitoring of stormwater discharges is conducted quarterly during qualifying storm events. Observations are documented including color, odor, clarity, floating solids, foam, and oil sheen. Results are retained for at least three years. |
| Benchmark monitoring | Benchmark monitoring is conducted for applicable parameters per permit sector requirements. Sampling is performed within the first 30 minutes of discharge (or as soon as practicable). Laboratory analysis uses approved methods. |
| Effluent limit monitoring | Effluent limit monitoring is conducted at required frequency for applicable parameters. Results are compared against numeric limits. Exceedances trigger corrective action and reporting requirements. |
| Annual comprehensive evaluation | Annual comprehensive site compliance evaluation is performed as required by permit. Evaluation covers all aspects of the SWPPP including BMP effectiveness, monitoring results, and potential plan modifications. |
BMPs and Controls
| Audit Item | Expected Finding / What to Evaluate |
|---|---|
| Good housekeeping | Facility maintains clean and orderly conditions. Material storage areas are organized and contained. Spills are cleaned promptly. Outdoor areas are swept or cleaned regularly. Waste receptacles are covered. |
| Structural BMPs | All structural BMPs (detention ponds, oil/water separators, filter systems, etc.) are installed as described in the SWPPP. BMPs are maintained and functioning as designed. Maintenance records are current. |
| Material management | Hazardous materials and chemicals are properly stored with cover and containment. Material Safety Data Sheets are available. Inventory of outdoor-stored materials is current. Spill response materials are available. |
| Vehicle/equipment areas | Vehicle maintenance areas have spill containment. Fueling areas have spill prevention measures. Equipment wash areas drain to proper treatment. No illicit discharges from vehicle operations. |
Reporting and Recordkeeping
| Audit Item | Expected Finding / What to Evaluate |
|---|---|
| Annual report | Annual report is submitted to the permitting authority by the required deadline. Report covers monitoring results, BMP assessments, and any corrective actions taken during the reporting period. |
| Record retention | All monitoring data, inspection records, and SWPPP amendments are retained for at least three years (or longer per state requirements). Records are organized and accessible for audits or inspections. |
| SWPPP amendments | SWPPP is amended when changes occur at the facility that affect stormwater management. Amendments are documented with dates and descriptions. Personnel are notified of SWPPP changes. |
| Training records | All personnel involved in stormwater management have received initial and annual training. Training covers the SWPPP, BMPs, good housekeeping, and spill response. Attendance records are maintained. |
Corrective Actions
Common Issues and Responses
- Benchmark exceedance: Investigate the source of the exceedance. Evaluate and modify BMPs as needed. Conduct follow-up monitoring. Document all corrective actions in the SWPPP.
- Expired permit coverage: Submit a new NOI immediately. Continue compliance with existing permit terms. Contact the permitting authority regarding coverage status and any interim requirements.
- Inadequate BMPs: Assess current BMP effectiveness against actual pollutant sources. Design and install additional or upgraded BMPs. Update the SWPPP to reflect changes. Monitor effectiveness after implementation.
- Missing monitoring data: Establish procedures to ensure sampling during qualifying storm events. Train sampling personnel on proper collection methods. Set up weather alerts to anticipate qualifying storms.
- Outdated SWPPP: Conduct a comprehensive review and update all sections. Verify site map accuracy, pollution source identification, and BMP descriptions. Obtain required certifications and distribute the updated plan.
Download the Free Checklist
Get our stormwater/swppp program audit checklist in Word format. Customize it for your organization.
Download Checklist (.docx)Ecesis EHS Software
Stormwater
Digital SWPPP management with BMP tracking, monitoring data, and compliance reporting.
Inspections
Scheduled BMP inspections with mobile forms, photo documentation, and deficiency tracking.
Water Quality
Laboratory data management with benchmark comparisons and exceedance alerts.
Compliance Calendar
Track monitoring deadlines, annual report dates, and permit renewal dates.
Document Management
Centralized SWPPP storage with amendment tracking and version control.
Task Management
Track corrective actions from inspections, audits, and monitoring exceedances.
