If you run a construction site that disturbs an acre or more of land, stormwater inspections are not optional paperwork. They are the heartbeat of your permit. Skip them, do them late, or fail to write them down, and you hand an inspector the easiest violation they will find all week. Get them right, and you have a dated, signed record that proves your site was managed responsibly every step of the way.
The most common question on a new site is simple: how often do we have to inspect? The answer comes straight from the EPA 2022 Construction General Permit (CGP), and it gives you a choice. Understanding that choice — and committing to one schedule — is the difference between a smooth project and one that grinds to a halt under a stop-work order.
The Two Inspection Schedules Under the EPA CGP
The EPA 2022 Construction General Permit offers operators two standard inspection frequency options. You pick one at the start of the project and follow it consistently.
Option A: Every 7 calendar days
Inspect the entire site at least once every seven calendar days. That is it. No matter the weather, no matter whether it rained, you walk the site and document conditions weekly.
This is the simpler of the two options because there is only one rule to remember. Seven days pass, you inspect. It does not depend on watching the forecast or tracking how much rain fell overnight.
Option B: Every 14 calendar days, plus within 24 hours of a qualifying storm
Inspect at least once every fourteen calendar days, AND inspect within 24 hours of the end of any storm event that produces 0.25 inches or more of rain. Under this option you go two weeks between routine inspections, but every meaningful rain event triggers an extra inspection on top of that schedule.
The 0.25-inch threshold is the federal trigger. A storm that drops a quarter inch or more of precipitation starts a 24-hour clock, and you must inspect before that clock runs out.
Both options satisfy the federal permit. The difference is purely about how the work is distributed: predictable weekly visits, or fewer routine visits paired with rain-driven ones.
Why Operators Pick One Schedule and Stick To It
The permit lets you choose, but it does not want you switching back and forth. You select a schedule and document it in your SWPPP, and that becomes the standard for the project. There are practical reasons most operators settle this early.
The 7-day schedule wins on simplicity. Crews on large sites, sites with many subcontractors, or sites in dry climates where rain is rare often prefer it. There is no rain gauge to monitor and no forecast to second-guess. The inspector shows up on the same day each week, and everyone knows the routine. In a dry season, you might inspect far more often than a rain-triggered schedule would require — but you never miss a trigger because there is no trigger to miss.
The 14-day-plus-storm schedule can mean fewer total inspections in dry stretches, which appeals to operators in arid regions or on smaller, slower-moving sites. The catch is vigilance. You have to track rainfall reliably and act fast when a qualifying storm hits. Miss the 24-hour window after a 0.25-inch rain, and you have a documented gap that an inspector can flag.
A few reasons consistency matters:
- Auditability. A regulator reviewing your records wants to see a predictable pattern. Inconsistent intervals look like guesswork and invite scrutiny.
- Crew habit. When the schedule is fixed, the inspection becomes routine and gets done. Ad hoc scheduling is how inspections get forgotten.
- Defensibility. If you ever face an enforcement question, a steady, documented cadence is your strongest evidence that the site was managed in good faith.
Pick the option that fits your site, your climate, and your staffing — then run it the same way for the life of the project.
The Post-Rain Trigger and Rain Gauges
For operators on the 14-day-plus-storm schedule, the rain trigger is the part that catches people out. The federal threshold is 0.25 inches of rainfall, and the 24-hour inspection window begins at the end of the storm event, not when the rain starts.
To use this schedule responsibly you need a defensible way to measure rainfall on or near the site. Common approaches include:
- An on-site rain gauge checked and logged daily. A simple physical gauge is cheap, reliable, and hard to argue with.
- A weather station that records precipitation electronically and timestamps it.
- A nearby official weather source, such as a National Weather Service station, when an on-site gauge is not practical. Document which source you rely on.
Whatever method you choose, write it into your SWPPP and keep the rainfall log with your inspection records. When an inspector asks how you knew a storm did or did not cross the 0.25-inch threshold, your rainfall data is the answer.
Two practical notes. First, the trigger is measured at the end of the storm, so a multi-day rain event is treated as one event for the 24-hour clock — confirm how your permit defines the end of an event. Second, even on the 7-day schedule, it is good practice to check the site after significant rain. Storms are when erosion and sediment discharge actually happen, so a post-rain walk often catches the problems that matter most.
What an Inspection Must Cover
Frequency is only half the rule. The other half is what you actually look at when you inspect. A compliant inspection under the CGP is a real walk of the site, not a desk exercise. At minimum, the inspector examines the following.
Best Management Practice (BMP) condition
Every control measure on the site gets checked for whether it is installed correctly and working. This includes:
- Perimeter controls such as silt fences, fiber rolls, and wattles — are they intact, trenched in, and not undermined or overtopped?
- Inlet protection at storm drains and catch basins.
- Sediment basins and traps — are they holding capacity, and do they need to be cleaned out?
- Stabilized construction entrances that keep tracked-out mud off public roads.
- Stockpile covers and protection.
- Stabilization measures on disturbed areas, including seeding, mulch, blankets, or other cover on slopes that have reached the point where stabilization is required.
Discharge points
Walk every location where stormwater leaves the site. Look for sediment, turbidity, sheen, or any other indicator that something other than clean stormwater is leaving the property. Discharge points are where a problem becomes a violation, so they get close attention.
Areas of concern and pollutant sources
Check material and waste storage, fueling and equipment maintenance areas, concrete washout, and any place a pollutant could reach stormwater. Look for evidence of erosion in disturbed soils and for sediment tracked or carried off site.
Corrective actions
When the inspection finds a problem — a failed silt fence, a clogged inlet, sediment past a perimeter control — it has to be recorded along with a corrective action. The permit expects deficiencies to be fixed promptly, generally before the next storm event and within a defined timeframe. The record should note what was wrong, what will be done, who is responsible, and when it was or will be corrected.
The point of an inspection is not just to observe. It is to catch failing controls before they discharge sediment, and to create a paper trail showing you did.
What the Written Record Must Show
An inspection that is not documented might as well not have happened. The CGP requires a written inspection report for each inspection, and the quality of that record is what protects you. A complete report typically includes:
- The date and time of the inspection.
- The name and title of the qualified person who performed it.
- Weather information, including whether the inspection was triggered by a storm and, where applicable, the rainfall amount and the storm's relevant timing.
- The scope of the inspection — what areas, BMPs, and discharge points were examined.
- Findings, including the condition of each control measure and any deficiencies or evidence of discharge.
- Corrective actions identified, with responsible parties and timeframes for completion, plus follow-up confirming earlier issues were resolved.
- A signature and certification by the inspector, with the date signed.
The signature matters. The CGP requires inspection reports to be signed and certified, and certification carries the weight of attesting that the information is true and complete. Keep these reports with your SWPPP and retain them for the period your permit requires — typically at least three years after permit coverage ends, though you should confirm the exact retention period in your permit.
Records must also be available when a regulator asks. A binder on site, or a digital record you can produce on demand, keeps you ready for an unannounced inspection.
Who Can Inspect: Qualified Personnel
The CGP does not let just anyone sign an inspection report. Inspections must be conducted by a qualified person — someone with the knowledge and training to assess site conditions, evaluate whether control measures are functioning, and identify the corrective actions needed.
This generally means a person who understands erosion and sediment control, stormwater BMPs, and the terms of your permit and SWPPP. Some operators use a trained member of their own staff; others bring in a certified inspector. A number of states and programs reference specific certifications such as a Certified Erosion, Sediment and Stormwater Inspector or equivalent state-recognized training. Whoever you use, the expectation is competence — the person signing must actually be able to do the job, not just sign the form.
How State Permits Can Be Stricter
Here is the part operators most often get wrong: the EPA CGP is the federal baseline, but most construction in the US is permitted by an authorized state program, not directly by EPA. The EPA CGP applies in only a limited set of jurisdictions — areas where EPA is the permitting authority, such as certain states, tribal lands, and territories.
In every state that runs its own NPDES construction stormwater program, the state permit controls, and a state permit can be — and often is — stricter than the federal CGP. State programs cannot be more lenient than the federal floor, but they are free to tighten it. Common ways state permits differ include:
- A lower rain trigger. Some states use a 0.5-inch storm threshold instead of the federal 0.25 inch, and some are stricter still. The trigger amount in your state's permit may not match the federal number.
- A fixed inspection frequency rather than a choice — some states simply require weekly inspections and do not offer the 14-day option.
- Specific certification requirements for who may inspect.
- Additional triggers tied to active versus stabilized areas, sensitive receiving waters, or seasonal conditions.
- Stricter record-keeping, reporting, or electronic submission requirements.
The takeaway is to never assume the federal numbers apply to your site. Read the permit that actually covers your project, confirm whether it is the EPA CGP or a state permit, and build your inspection schedule from that document. When the federal CGP and a state permit both seem to apply, the state permit's stricter terms govern.
How Good Records Prevent Stop-Work Orders and Fines
Stormwater enforcement on construction sites tends to follow a pattern. An inspector arrives, asks to see the SWPPP and the inspection records, and walks the site. Two things get them in trouble fast: controls that are obviously failing, and records that are missing, late, or unsigned.
A consistent, well-documented inspection program defends against both. Inspecting on schedule means failing controls get caught and fixed before they discharge — so the site itself looks managed. And a clean record of dated, signed inspections with documented corrective actions shows that the program is real and ongoing, not reconstructed the night before.
When records are solid, an inspector who finds a minor issue is far more likely to note it and move on, because the paperwork shows a responsible operator who fixes problems. When records are missing or sloppy, the same minor issue can escalate — to a notice of violation, a penalty, or a stop-work order that halts the project until the program is brought into compliance. A stopped job costs far more in idle crews and blown schedules than the inspections ever would have.
Good records do not just prove compliance. They are the cheapest insurance on the site.
Setting Up the Right Schedule for Your Permit
The inspection rule is straightforward once you know which permit you are under and which schedule you have chosen — but pulling the right threshold, the right cadence, and the right record format out of your specific permit is where projects get tripped up.
Siltworks builds your SWPPP with the inspection schedule that matches your permit, so the right frequency, the correct rain trigger, and a complete inspection record format are set up from day one. You stay inspection-ready, and your crew always knows exactly when to walk the site and what to write down.