SWPPP Requirements in California: Construction and Industrial Permit Guide

Short answer: In California, a SWPPP is required for construction projects that disturb one acre or more (Construction General Permit, Order 2022-0057-DWQ) and for industrial facilities in the regulated SIC categories (Industrial General Permit, Order 2014-0057-DWQ as amended). Each permit then requires inspections, monitoring, and filings in SMARTS, including an annual report: September 1 for construction sites and July 15 for industrial facilities.

This guide lays out the requirements of both permits side by side, with a filing calendar at the end. For the basics of the plan itself, start with what a SWPPP is.

CGP or IGP: which permit applies?

	Construction General Permit	Industrial General Permit
Order	2022-0057-DWQ (NPDES No. CAS000002)	2014-0057-DWQ, amended by 2015-0122-DWQ and 2018-0028-DWQ
Effective	September 1, 2023	Amended version effective July 1, 2020
Trigger	Soil disturbance of one acre or more, or less than one acre within a larger common plan of development of one acre or more	Industrial activity in a category listed in Attachment A, by SIC code
How you enroll	Permit Registration Documents in SMARTS before construction starts	Permit Registration Documents in SMARTS at least seven days before industrial activity starts
Who prepares the SWPPP	A Qualified SWPPP Developer (QSD)	The discharger
Exit	Notice of Termination	Notice of Termination, or No Exposure Certification if the facility qualifies
Annual report	September 1	July 15

About the old construction permit. The 2022 CGP replaced Order 2009-0009-DWQ. Projects still covered by the 2009 permit had until August 31, 2025, to certify their intent to move to the new permit and submit revised documents, and existing 2009 permit Notices of Intent were administratively terminated two years after September 1, 2023 (CGP Section III.C). Every active construction site should now be under the 2022 permit.

About the industrial permit’s status. The IGP’s term ended June 30, 2020. The State Water Board’s permit page states it is administratively continued under 40 CFR 122.6 until a new permit is issued, so the amended 2014 order remains the one to follow.

Construction General Permit requirements

Enrollment

Before construction begins, the discharger certifies and submits Permit Registration Documents in SMARTS: the Notice of Intent with the Risk Level determination, site drawings and maps, the SWPPP, any required post-construction plans and calculations, and the annual fee under the State Water Board’s fee regulations (CGP Section III.A.1). Coverage begins when SMARTS issues a WDID number, which must be posted where the public can see it or be available on request. In a public emergency, the discharger notifies the Regional Water Board within five calendar days and files the documents within 30 calendar days.

Risk levels

Traditional construction projects are assigned Risk Level 1, 2, or 3. The level combines two factors (Attachment D.1 and the CGP Fact Sheet):

• Sediment risk: calculated by multiplying the rainfall erosivity (R), soil erodibility (K), and length-slope (LS) factors from the Revised Universal Soil Loss Equation. Soil loss under 15 tons per acre is low, 15 to 75 tons per acre is medium, and over 75 tons per acre is high.
• Receiving water risk: high if the project drains to a water body on the 303(d) list for sediment impairment, or one with the COLD, SPAWN, and MIGRATORY beneficial uses. Otherwise low.

SMARTS calculates the combined Risk Level from the information entered. The level matters because it drives sampling.

Requirement	Risk Level 1	Risk Level 2	Risk Level 3
Weekly visual inspections	Yes	Yes	Yes
Pre-, during, and post-storm inspections	Yes	Yes	Yes
Stormwater discharge sampling (pH and turbidity)	No	Yes	Yes
Non-visible pollutant sampling	As applicable	As applicable	As applicable
Receiving water monitoring	No	No	When triggered

For Risk Level 2 and 3 sites, the numeric action levels are a pH range of 6.5 to 8.5 and turbidity of 250 NTU (CGP Section IV.C.3). Risk Level 3 sites that discharge directly to a receiving water must also monitor that water if discharge results show pH outside 6.0 to 9.0 or turbidity above 500 NTU (Attachment D, III.D.2). Linear underground and overhead projects use a separate project type system in Attachment E.

Inspections

Under Attachment D, Section III.C, dischargers must:

• inspect BMPs weekly; a storm-related inspection also counts as the weekly inspection;
• have a QSP inspect within 72 hours before any forecast with a 50 percent or greater chance of 0.5 inches or more in 24 hours (a Qualifying Precipitation Event), or up to 120 hours ahead when an extended National Weather Service forecast is available;
• inspect at least once every 24 hours during a Qualifying Precipitation Event; and
• inspect within 96 hours after an event if the on-site rain gauge measured 0.5 inches or more.

On top of these, a QSP inspects monthly and a QSD visits within 30 days of construction starting and twice a year (once August through October, once January through March). See QSD vs QSP in California for the full list.

Sampling

Risk Level 2 and 3 sites take grab samples from every discharge location, one per 24-hour period of each Qualifying Precipitation Event during active discharge, and analyze them for pH and turbidity plus any parameter the Regional Water Board requires (Attachment D, III.D.1).

Annual report and records

The annual report is certified and submitted in SMARTS by September 1 for the July 1 to June 30 reporting period, if the WDID was active for at least 90 days in that period (CGP Section IV.P). It summarizes sampling, corrective actions, missed inspections or sampling, permit violations, who did the inspections, and precipitation amounts. Keep each annual report, and all required records, for at least three years (Sections IV.P.2 and VI.F).

Industrial General Permit requirements

Visual observations

At least once per calendar month, the discharger visually observes each drainage area for unauthorized non-stormwater discharges, authorized non-stormwater discharges and their BMPs, and outdoor industrial equipment, storage, and activity areas. Monthly observations take place in daylight, during scheduled operating hours, on days without precipitation. Sampling event observations are made at the same time samples are collected (IGP Section XI.A).

Sampling

A Qualifying Storm Event (QSE) is a precipitation event that produces a discharge from at least one drainage area and is preceded by 48 hours with no discharge from any drainage area. The discharger must sample:

• two QSEs in the first half of the reporting year (July 1 to December 31), and
• two QSEs in the second half (January 1 to June 30).

Compliance Group participants sample one QSE in each half. Samples are collected within four hours of the start of discharge, or of the start of facility operations if the storm began in the previous 12 hours. Every sample is analyzed for total suspended solids, oil and grease, and pH, plus parameters tied to the facility’s pollutant sources, its SIC code, and any 303(d) impairment or TMDL for the receiving water (IGP Section XI.B). Results are submitted in SMARTS within 30 days of obtaining all results for each sampling event.

Exceedance Response Actions

When the annual average for a parameter, or two or more instantaneous results in a reporting year, exceed the permit’s numeric action levels, the facility moves from Baseline to Level 1 status on July 1 after that reporting year (IGP Section XII). At that point the facility must designate a QISP.

Step	Deadline
Level 1 ERA Evaluation of pollutant sources, with QISP assistance	October 1 after Level 1 status begins
Level 1 ERA Report prepared by a QISP, filed in SMARTS	No later than January 1 after Level 1 status begins
Level 2 ERA Action Plan prepared by a QISP (if exceedances continue while in Level 1)	January 1 after the reporting year of the exceedance

A facility returns to Baseline once its Level 1 report is complete, the new BMPs are in place, and four consecutive QSEs show no further exceedance for that parameter.

Annual Evaluation and annual report

The discharger conducts one Annual Comprehensive Facility Compliance Evaluation each reporting year, reviewing records and inspecting industrial areas, BMPs, and equipment. If the evaluation is done fewer than 8 or more than 16 months after the previous one, the reason must be documented. SWPPP revisions it identifies are made within 90 days (IGP Section XV).

The annual report is certified in SMARTS no later than July 15 after each reporting year (IGP Section XVI). It includes a compliance checklist, an explanation of any noncompliance, the SWPPP revisions made that year, and the date of the Annual Evaluation.

SWPPP updates

Significant SWPPP revisions are certified and submitted in SMARTS within 30 days. Other revisions do not need to be submitted more than once every three months (IGP Section X.B).

SMARTS filing calendar

Filing	Permit	Deadline
Permit Registration Documents	CGP	Before construction starts
Permit Registration Documents	IGP	At least 7 days before industrial activity starts
SWPPP amendments	CGP	Within 30 calendar days
Significant SWPPP revisions	IGP	Within 30 days
Contact information changes	CGP	Within 90 days of a change
Sampling results	IGP	Within 30 days of obtaining all results
Level 1 ERA Report	IGP	January 1 after Level 1 status begins
Annual report	IGP	July 15
Annual report	CGP	September 1

Practical tips

• Put the forecast on the calendar. The pre-storm inspection has to happen within 72 hours before the forecast event, so someone needs to watch the National Weather Service forecast for the site’s zip code.
• Track the first half of the IGP year. If a facility reaches December 31 without two sampled QSEs, it cannot catch up later in the year.
• Check SMARTS, not just your files. Regulators see what is in SMARTS: the SWPPP version, contacts, and reports.
• Read your local permit. Cities and counties can attach their own stormwater conditions to grading and building permits.

How Exodus helps

Exodus Water Services keeps inspections, sampling, and SMARTS filings on one compliance calendar for construction sites and industrial facilities, with certified stormwater staff who prepare and update SWPPPs. See our stormwater compliance services, read understanding stormwater compliance requirements for regulated facilities, or contact us. Call (805) 991-7333 to review your permit obligations.

Frequently asked questions

When is the Industrial General Permit annual report due? No later than July 15 after each reporting year, which runs July 1 through June 30. It is certified and submitted in SMARTS.

When is the Construction General Permit annual report due? By September 1 for the previous July 1 to June 30 reporting period, if the site’s WDID number was active for at least 90 days in that period.

How is a construction site’s risk level determined? By combining sediment risk, calculated from rainfall erosivity, soil erodibility, and slope, with receiving water risk, based on whether the site drains to a sediment-sensitive water body. SMARTS calculates the combined Risk Level 1, 2, or 3.

How many storm samples does an industrial facility need each year? Four: two Qualifying Storm Events between July 1 and December 31, and two between January 1 and June 30. Compliance Group participants sample one in each half.

How often must a construction site be inspected? Weekly, plus a QSP inspection within 72 hours before a forecasted Qualifying Precipitation Event, inspections every 24 hours during the event, and a post-event inspection within 96 hours when 0.5 inches or more is measured on site.

What is SMARTS? The Stormwater Multiple Application and Report Tracking System, the State Water Board’s online system where dischargers enroll, upload SWPPPs, and submit monitoring data and annual reports.

Is the 2009 Construction General Permit still in effect? No. Coverage under Order 2009-0009-DWQ was administratively terminated two years after the 2022 permit took effect on September 1, 2023. Projects needing coverage after September 1, 2025, had to transition to the 2022 permit.

Last reviewed: October 30, 2026.

Sources

• State Water Board, Construction Stormwater Program
• State Water Board, 2022 Construction Stormwater General Permit, Order 2022-0057-DWQ: Order Sections III, IV.C, IV.P, V, and VI.F; Attachments D and D.1; Fact Sheet Section I.R
• State Water Board, Industrial Stormwater Program
• State Water Board, Industrial General Permit order page
• State Water Board, Industrial General Permit, Order 2014-0057-DWQ as amended (PDF): Sections X, XI, XII, XV, and XVI
• State Water Board, SMARTS resources