Who needs a SWPPP in California?
Any construction project that disturbs one acre or more — or is part of a larger common plan of development reaching one acre — needs a SWPPP under California permit 2022-0057-DWQ.
California runs its own delegated stormwater program. Operators obtain coverage from State Water Resources Control Board under California Construction General Permit (2022-0057-DWQ), not directly from the EPA. A small subdivision, a solar pad, and a road-widening project all clear the same one-acre line.
California adds requirements worth flagging early: Risk Level determination (1-3); SMARTS electronic filing; Sampling and monitoring per Risk Level.
What the plan must contain
A California SWPPPis the site's compliance binder — the document an inspector opens first. It documents:
- 1Site & project descriptionTotal and disturbed acreage, soils, slopes, and the sequence of construction.
- 2Receiving waters & discharge pointsWhere stormwater leaves the site and the waterbodies it reaches.
- 3Erosion & sediment control BMPsSilt fence, stabilized entrances, inlet protection, and stabilization measures.
- 4Inspection schedule & recordsDated, signed inspection logs and the corrective actions taken.
- 5Operator certificationThe SWPPP is signed by the legally responsible party before work begins.
Required and conditional BMPs
| Best management practice | Category | Status |
|---|---|---|
| Perimeter silt fence / sediment barrier | Sediment control | Required |
| Stabilized construction entrance | Tracking control | Required |
| Storm drain inlet protection | Sediment control | Required |
| Soil stabilization (seeding, mulch, blankets) | Erosion control | Required |
| Concrete washout containment | Good housekeeping | Required |
| Sediment basin or trap | Sediment control | Conditional |
| Dewatering / turbidity controls | Pollution prevention | Conditional |
Filing your Notice of Intent
File the Permit Registration Documents (NOI, SWPPP, risk assessment) via SMARTS.
A Notice of Termination closes coverage once the site reaches final stabilization. Keeping the SWPPP and its inspection records on site is what keeps a project clear of stop-work orders.
Inspection requirements
Inspect at least once every calendar week and by a QSP within 72 hours before any weather pattern forecast to have a 50 percent or greater chance of 0.5 inches or more in a 24-hour period and within 96 hours after a storm producing 0.5 inch of rain or more measured with the onsite rain gauge during a Qualifying Precipitation Event (the pre-event inspection may be done up to 120 hours in advance when extended National Weather Service forecast data is available; inspect at least once every 24-hour period during a Qualifying Precipitation Event, extended for each subsequent 24-hour period forecast to have at least 0.25 inches of precipitation; a pre-, during-, or post-event inspection also satisfies the weekly inspection; inspections are conducted by the QSD, the QSP, or a person trained by the QSP during scheduled site operating hours, and are not required during dangerous weather conditions, outside scheduled site operating hours, or when the site is not accessible) (Order WQ 2022-0057-DWQ Attachment D, Sections III.B.1 and III.C.1–III.C.6 (Table 2)). Table 2 sets this visual inspection schedule for Risk Levels 1, 2, and 3 alike; sampling depends on the Risk Level (Attachment D, Section III.D). A QSP also inspects the site once every calendar month, and within 14 days after a numeric action level exceedance (Order Section V.D.2). A QSD performs on-site visual inspections within 30 days of construction activities commencing, within 30 days of the discharger replacing the QSD, twice annually (once August through October and once January through March), within 14 calendar days after a numeric action level exceedance, and within the time period Water Board staff request in writing (Order Section V.C.4.a–e). For an inactive project whose Change of Information is approved by the Regional Water Board, a QSP or trained delegate inspects at least once every calendar month and before any weather pattern forecast to have a 50 percent or greater chance of 0.5 inches or more in a 24-hour period (Order Section III.G.2.b; Attachment D, Section III.B.2). Every inspection is dated and signed, and any failed control is corrected before the next storm.
| Trigger | Requirement |
|---|---|
| Routine | At least once every calendar week and by a QSP within 72 hours before any weather pattern forecast to have a 50 percent or greater chance of 0.5 inches or more in a 24-hour period and within 96 hours after a storm producing 0.5 inch of rain or more measured with the onsite rain gauge during a Qualifying Precipitation Event (the pre-event inspection may be done up to 120 hours in advance when extended National Weather Service forecast data is available; inspect at least once every 24-hour period during a Qualifying Precipitation Event, extended for each subsequent 24-hour period forecast to have at least 0.25 inches of precipitation; a pre-, during-, or post-event inspection also satisfies the weekly inspection; inspections are conducted by the QSD, the QSP, or a person trained by the QSP during scheduled site operating hours, and are not required during dangerous weather conditions, outside scheduled site operating hours, or when the site is not accessible) |
How California differs from the federal permit
| California | Federal (EPA) | |
|---|---|---|
| Authority | State Water Resources Control Board | U.S. EPA |
| Permit | 2022-0057-DWQ | EPA CGP |
| Disturbance threshold | 1 acre | 1 acre |
| Plan name | SWPPP | SWPPP |
Because California administers its own program, the federal EPA Construction General Permit does not apply directly here — the state permit governs. Sites inside a regulated municipal storm sewer system may carry additional local ordinance requirements on top of the state permit.
Frequently asked questions
Does California require an engineer to prepare the SWPPP?+–
No. California does not require a licensed PE stamp on a construction SWPPP statewide. The operator certifies the plan; engineer review is optional for complex sites.
What is the disturbance threshold in California?+–
One acre — including sites under an acre that are part of a larger common plan of development totaling one acre or more.
How often must inspections happen in California?+–
Inspect at least once every calendar week and by a QSP within 72 hours before any weather pattern forecast to have a 50 percent or greater chance of 0.5 inches or more in a 24-hour period and within 96 hours after a storm producing 0.5 inch of rain or more measured with the onsite rain gauge during a Qualifying Precipitation Event (the pre-event inspection may be done up to 120 hours in advance when extended National Weather Service forecast data is available; inspect at least once every 24-hour period during a Qualifying Precipitation Event, extended for each subsequent 24-hour period forecast to have at least 0.25 inches of precipitation; a pre-, during-, or post-event inspection also satisfies the weekly inspection; inspections are conducted by the QSD, the QSP, or a person trained by the QSP during scheduled site operating hours, and are not required during dangerous weather conditions, outside scheduled site operating hours, or when the site is not accessible) (Order WQ 2022-0057-DWQ Attachment D, Sections III.B.1 and III.C.1–III.C.6 (Table 2)). Table 2 sets this visual inspection schedule for Risk Levels 1, 2, and 3 alike; sampling depends on the Risk Level (Attachment D, Section III.D). A QSP also inspects the site once every calendar month, and within 14 days after a numeric action level exceedance (Order Section V.D.2). A QSD performs on-site visual inspections within 30 days of construction activities commencing, within 30 days of the discharger replacing the QSD, twice annually (once August through October and once January through March), within 14 calendar days after a numeric action level exceedance, and within the time period Water Board staff request in writing (Order Section V.C.4.a–e). For an inactive project whose Change of Information is approved by the Regional Water Board, a QSP or trained delegate inspects at least once every calendar month and before any weather pattern forecast to have a 50 percent or greater chance of 0.5 inches or more in a 24-hour period (Order Section III.G.2.b; Attachment D, Section III.B.2).
What is a QSD and does my site need one?+–
A Qualified SWPPP Developer (QSD) must develop and certify the SWPPP; a Qualified SWPPP Practitioner (QSP) oversees implementation.
California-ready in minutes
Siltworks fills in your site data automatically, applies the California requirements, and hands you an inspection-ready SWPPP — at 70–90% less than a consultant.
Requirements summarized from the publicly available California Construction General Permit (2022-0057-DWQ) for planning purposes. The operator must review and certify every SWPPP before use.