How to Conduct a Stormwater Inspection

A stormwater inspection is a structured site walkdown to verify that the Best Management Practices (BMPs) documented in your SWPPP are installed, functioning as designed, and being properly maintained. Inspections are required under the Clean Water Act for all construction sites covered by the EPA CGP or an equivalent state permit.

The purpose is twofold: to catch BMP failures before they result in a discharge of polluted stormwater, and to create a documented record showing that the site is actively managed for permit compliance. Inspection reports become part of the SWPPP record and must be available for review by regulators at any time.

The CGP requires that inspections be performed by a "qualified personnel" — someone who is knowledgeable about the provisions of the permit, the SWPPP, and the BMPs implemented on the site. This does not require a licensed engineer, but it does require demonstrated familiarity with:

• The site-specific SWPPP and the BMPs it describes
• The permit's inspection requirements and corrective action thresholds
• How to identify BMP failures or inadequacies in the field

Many operators designate a site superintendent, project manager, or environmental compliance officer as the qualified inspector. The SWPPP must identify who is authorized to perform inspections by name or by title.

Some state permits go further and require a certified inspector (e.g., a Certified Inspector of Stormwater Quality, or CISQ). Always check your state permit for inspector qualification requirements beyond the federal baseline.

The EPA CGP establishes two inspection schedules. Operators must satisfy both:

Routine Schedule

At least once every seven calendar days, or at least once every 14 calendar days and within 24 hours of the end of a storm event that produces 0.25 inches or more of rainfall. You choose which schedule applies, and document it in the SWPPP.

Post-Storm Inspections

When operating on the 14-day schedule, a rainfall event of 0.25 inches or more triggers a required inspection within 24 hours of the storm ending. The 24-hour clock starts when precipitation stops, not when it begins.

Impaired Waters

Sites that discharge to waters listed as impaired under Section 303(d), or subject to a TMDL for a stormwater pollutant, must inspect at least once every seven calendar days regardless of which routine schedule is otherwise used.

Frozen Ground Exception

Inspections may be reduced to once per month when construction activity is temporarily halted due to frozen ground conditions and runoff is unlikely. This exception ends as soon as thaw begins and must be documented in the SWPPP.

Final Stabilization

Once an area has achieved final stabilization, inspections of that area may be discontinued. Inspections must continue on any remaining disturbed areas until the entire site reaches final stabilization.

State permits often impose stricter frequency requirements. Always confirm your applicable permit's inspection schedule before adopting the federal baseline.

The CGP specifies the areas and BMPs that must be evaluated during each inspection. Work systematically through the site using the SWPPP BMP list as your checklist:

Disturbed Areas

Check all areas of active clearing, grading, and excavation for adequate erosion control. Verify that any area idle for more than 14 days (or 7 days near impaired waters) has been temporarily stabilized.

Erosion & Sediment Controls

Inspect silt fences, fiber rolls, compost berms, sediment traps, and basins for damage, undercutting, overtopping, or excessive sediment accumulation. Controls that have reached 50% capacity must be cleaned out or replaced.

Perimeter Controls

Walk the entire site perimeter to confirm the continuous barrier is intact. Look for gaps, washouts, or areas where sediment has bypassed controls and left the site.

Storm Drain Inlets

Check every inlet on or adjacent to the site. Inlet filters, rock dams, or silt sacks must be clean and in place. Remove any sediment that has accumulated inside inlets.

Stabilized Construction Entrance

Inspect the rock pad or wheel wash station at all vehicle exit points for signs of trackout onto public roads. A functioning stabilized entrance should not deposit visible mud beyond the site boundary.

Slopes

Look for rill erosion, gullying, or failure of slope protection measures such as erosion control blankets, slope drains, or interceptor swales. Slope failures require immediate corrective action.

Good Housekeeping Areas

Inspect fueling areas, material storage, concrete washout, solid waste containers, and portable sanitation facilities. Confirm secondary containment is intact, lids are secured, and no spills or leaks are present.

Discharge Points

Check all identified outfalls and any locations where stormwater leaves the site. Look for signs of visible turbidity, sheen, foam, or discoloration in any discharge. Any discharge that appears polluted must be documented and addressed immediately.

An inspection report must be completed within 24 hours of completing the inspection. The CGP specifies the minimum content each report must include:

• Date and time of the inspection
• Name and title of the inspector
• Weather conditions at the time of inspection and since the last inspection
• Location of each BMP inspected
• Condition of each BMP — functioning as designed, needs maintenance, or failed
• Any visible signs of stormwater pollution (turbidity, sheen, sediment deposits off-site)
• Any corrective actions taken or needed, with the date each action is required to be completed
• Certification statement signed by the inspector

Photographs are not required by the CGP but are strongly recommended. A timestamped photo of each BMP condition creates an unambiguous record if compliance is ever challenged. Store photos as part of the inspection report.

When an inspection identifies a BMP that is not functioning as designed, the CGP requires you to act:

Immediate Repairs

BMPs that have failed and are allowing sediment or other pollutants to leave the site must be repaired, replaced, or supplemented immediately — or as soon as field conditions allow. "As soon as practicable" is defined by the CGP as no later than seven calendar days from the date the problem was identified.

Discharges of Concern

If you observe a discharge that may have caused or contributed to a water quality standard violation, you must take corrective action immediately, document the discharge in the inspection report, and retain all related records for at least three years.

SWPPP Amendment

If a corrective action results in a change to your BMP strategy — adding a new control, relocating an existing one, or revising the inspection schedule — the SWPPP must be updated to reflect the change. Date and document every amendment.

Tracking Open Items

Each unresolved finding from an inspection should be tracked as an open action item until it is closed. The follow-up inspection must confirm that the corrective action was completed, and that confirmation must be noted in the subsequent report.

When operating on the 14-day routine schedule, a storm that produces 0.25 inches or more of rainfall triggers a separate post-storm inspection requirement. This inspection has different timing and focus from a routine walkdown:

Timing

The post-storm inspection must be completed within 24 hours of the end of the rainfall event. If completing an inspection within 24 hours is not feasible due to unsafe site conditions (e.g., standing water, lightning risk), document the reason and complete the inspection as soon as it is safe to do so.

Rainfall Threshold

The 0.25-inch trigger applies to rainfall measured at or near the site. Using a rain gauge at the site is the most reliable method. A weather station within a few miles may be used if a site-specific gauge is not practical, but document the data source in the report.

Focus Areas

Post-storm inspections should focus on areas most likely to show damage: sediment that has washed past perimeter controls, BMP displacement from storm flows, inlet protection failure, and any off-site sediment deposition. Document any discharge observed during or immediately after the storm.

Resetting the 14-Day Clock

A post-storm inspection counts as a routine inspection for the purpose of resetting the 14-day calendar. You do not need to conduct a separate routine inspection within 14 days of a completed post-storm inspection.

All inspection reports must be retained as part of the SWPPP record. The CGP requires these records to be available on-site or accessible electronically during an inspection by any regulatory authority.

On-Site Availability

Inspection reports must be on-site or immediately accessible during normal business hours. Digital storage on a phone or tablet is acceptable as long as it is accessible on demand.

Retention Period

All inspection records — reports, corrective action documentation, and supporting photographs — must be retained for at least three years after permit coverage ends. The three-year period begins from the date you submit your Notice of Termination (NOT).

What Must Be Kept

Completed inspection reports, any records of corrective actions taken, documentation of any discharges observed during or immediately after storms, and training records for personnel who conducted inspections.

State Requirements

Some states require longer retention periods or mandate submission of inspection reports to the permitting authority at defined intervals. Verify your state permit's recordkeeping requirements — they may exceed the federal minimum.