On October 16, 2026, the State Water Resources Control Board sent a letter to every facility covered by the Industrial General Permit (IGP). The message is simple: NOAA is predicting a potentially historic El Niño this winter, and every IGP requirement stays in effect, no matter how hard it rains.
The letter also includes a warning. Because this El Niño has been forecast for a long time, the Water Boards will look at any unauthorized stormwater discharge and ask whether the facility prepared. If you can't show you took reasonable steps ahead of time, that will be considered when deciding on enforcement.
Here's what that means for your facility.
1. Keep up your visual observations
- Monthly dry-weather observations (Section XI.A.1): do them during daylight, on scheduled operating hours, on days without rain. Use them to confirm the site is ready for storms and that there are no non-stormwater discharges.
- Observations during sampling (Section XI.A.2): required every time you sample.
- Fix what you find (Section XI.A.3): if an observation shows pollutant sources aren't controlled, revise your BMPs.
- Any observation you miss has to be explained in your Annual Report.
2. Sample your qualifying storm events on time
- Collect samples within four hours of the start of discharge, or at the start of operations if discharge began before you opened (Section XI.B).
- Most facilities need four QSEs per reporting year: two between July 1 and December 31 and two between January 1 and June 30. Compliance Group members and facilities with a Sampling Frequency Reduction Certification need one in each half.
- Upload results to SMARTS as an Ad Hoc report within 30 days of getting lab results (Section XI.B.11.a).
With a wet winter ahead, there should be plenty of qualifying storms. Have your sampling kit, chain-of-custody forms and lab lined up now.
3. Safety comes first
The Water Board says it prioritizes safety. Under Section XI.C.6, you don't have to sample or observe outside scheduled operating hours or during dangerous conditions such as flooding, electrical storms, high mudslide risk, government closures, or anything else that blocks safe access. You still have to explain every missed sample or observation in your Annual Report, so record the date, the conditions and the reason when it happens.
4. Shutting down for 10 days or more? File before you go
If you plan to suspend industrial activities for 10 or more consecutive days, you can ask to suspend monitoring (Section X.H.3). Two things must be true: monitoring isn't feasible because the site is unstaffed, remote or inaccessible, and the facility is stabilized with BMPs in place. You must upload a Change of Information in SMARTS at least 7 days before the suspension that includes:
- A SWPPP revision covering your stabilization BMPs
- Why monitoring isn't feasible during the suspension
- The date the facility was fully stabilized
- The date you expect to resume operations
Regional Board staff can ask for changes or deny the request.
5. Tell the Board before planned changes cause problems
Under Section XXI.M, you must give advance notice to your Regional Water Board and local MS4 of any planned change in industrial activity that could lead to noncompliance.
What to do this month
- Walk your site with your SWPPP in hand and check drainage, storage areas, outdoor material handling and BMP condition.
- Fix or upgrade BMPs before the big storms, and document it with dated photos and notes.
- Confirm who samples, when, and where the supplies are kept.
- Set up a simple log for missed observations or samples and the reason for each.
- If you'll be closed for 10 or more days, get the SMARTS Change of Information in early.
Your best protection from enforcement this winter is records showing you prepared.
Need help getting ready?
Stormwater.Pro helps California industrial facilities with SWPPP updates, BMP inspections, QSE sampling and SMARTS reporting. Book a free stormwater compliance assessment and we'll help you get ready before the storms arrive.
Source: State Water Resources Control Board, "Industrial Facility Preparation for the Historic El Niño Event," October 16, 2026. Read the letter.
