Where to Look Up Your Facility's SIC Code, How to Pick the Right One, and What It Tells You About PAG-03 Coverage and Stormwater Monitoring
If you've started reading about industrial stormwater permits in Pennsylvania, you've probably hit the same wall a lot of business owners do. Everything seems to hinge on your SIC code, and you have no idea what yours is. That's not a failure on your part. The federal government largely stopped using SIC codes years ago, so most companies today only see the newer NAICS codes on their tax forms and business registrations. But the stormwater rules still run on SIC codes, so you need to know yours to figure out whether DEP expects you to have a permit.
The short answer is that you can usually find your SIC code in your old permits, your Dun & Bradstreet record, or by converting the NAICS code from your tax return, and you can confirm it with OSHA's free SIC search tool. What counts is the code for your facility's primary activity, which DEP defines as the activity that brings in the most revenue. Once you have it, you compare it against the categories covered by PAG-03, Pennsylvania's general permit for industrial stormwater, and that tells you whether you need coverage and which sector appendix (and monitoring) applies. Below, we walk through where to look, how to pick the right code, how it maps to PAG-03, and what to do when the answer isn't clean. If you'd rather have someone look at it with you, feel free to reach out to RMA.
Table of Contents
TL;DR
Your SIC code is a four-digit industry code, and Pennsylvania's industrial stormwater rules still use it even though most government forms now use NAICS codes instead. You can usually find it in old permits or business credit records, or by converting the NAICS code on your tax return and checking it with OSHA's free online search. The code that counts is the one for the activity that brings in the most money at that specific site. Compare it to the industries covered by the state's general stormwater permit to see whether you need coverage and which monitoring applies, and if the answer is unclear, document your reasoning and check with DEP or someone who does this work before you file.
What Is a SIC Code and Why Does It Matter for PA Stormwater Permits?
SIC stands for Standard Industrial Classification. It's a four-digit code the federal government created to sort businesses by what they do. The first two digits are the broad industry group, and the last two narrow it down. For example, codes starting with 32 cover stone, clay, glass, and concrete products, and 3273 is ready-mixed concrete specifically. The SIC manual was last updated in 1987, and in 1997 federal agencies began switching to the North American Industry Classification System, or NAICS, which uses six digits and different groupings. That's why your accountant, your state business registration, and most federal forms today talk about NAICS, not SIC.
Stormwater is one of the places the old system never went away. The federal rule that defines which facilities need industrial stormwater permits, 40 CFR 122.26(b)(14), is written largely in SIC codes, and Pennsylvania's PAG-03 general permit follows the same structure. PAG-03 is the permit most industrial facilities in the state use to get NPDES coverage for stormwater, meaning rain and snowmelt that runs off areas where industrial activity happens. So when DEP asks for your SIC code on a Notice of Intent, or when you're trying to figure out whether you need a permit at all, the four-digit code is where the answer starts. If you're new to the basic concept, our article on stormwater associated with industrial activity covers the background.
Where Can You Find Your Facility's SIC Code?
Most businesses already have an SIC code floating around in their records, even if nobody's looked at it in years. The trick is knowing where it shows up. Some sources give you the SIC code directly. Others give you a NAICS code that you'll need to convert. Either way, treat whatever you find as a starting point to check, not the final word, because codes in third-party databases are sometimes assigned by someone who never saw your operation.
| Where to Look |
What You'll Find |
Things to Watch For |
| Past environmental permits and filings |
SIC codes on old stormwater NOIs, air permits, or other DEP applications |
Often the best source, but check that operations haven't changed since |
| Tax filings |
A NAICS-based principal business activity code |
Needs converting to SIC, and it describes the company, not necessarily each site |
| Dun & Bradstreet record |
Primary and secondary SIC codes in your business credit profile |
Assigned by D&B, so verify it matches what the site does |
| OSHA's SIC search |
The full SIC manual, searchable by keyword, with descriptions for each code |
Free and easy to use, and the source DEP itself points to |
| NAICS-to-SIC crosswalks |
Tables that match NAICS codes to the closest SIC codes |
One NAICS code can map to several SIC codes, so read the descriptions |
If you can't find a code anywhere, you can work it out yourself. Open OSHA's SIC search, search for words that describe what you make or do, and read the descriptions for the codes that come up. The manual describes each industry in plain terms and lists example products, so it's usually clear within a few minutes whether "fabricated structural metal" or "metal stampings" fits your shop better. DEP's own industrial stormwater FAQ points readers to the OSHA tool for this, and it also references NAICS-to-SIC crosswalks for people who only have a NAICS code. When you settle on a code, write down where you got it and why it fits.
How Do You Choose the Right Primary SIC Code for Stormwater?
Plenty of facilities do more than one thing, and each activity can have its own SIC code. For stormwater, the one that drives the decision is the primary SIC code. DEP's industrial stormwater FAQ says the primary activity is the one that generates the most revenue at the facility. So a plant that makes precast concrete products and also runs a small trucking operation would generally use the precast code, not the trucking code, as long as the precast work brings in more money.
Secondary activities matter less than people fear, but they don't disappear. DEP's FAQ explains that if only a secondary SIC code is on the covered list, you generally don't need coverage unless DEP decides you do. On-site support operations, like a warehouse or a maintenance shop that serves the main business, are treated as secondary. The flip side is that if your primary code is covered and you also have secondary activities that fall under a different PAG-03 appendix, the requirements of each applicable appendix apply at your site.
The code also belongs to the facility, not the company. If you run three locations, each one gets its own primary SIC code based on what happens there. Your headquarters might be an office with no stormwater obligations at all, your production plant might be squarely covered, and your distribution yard might fall somewhere in between. Don't copy one site's code onto another site's paperwork. Industrial parks add another wrinkle, since tenants doing different work can each have their own codes. DEP's FAQ allows the owner to hold one permit, tenants to be co-permittees, or each tenant to file separately when the other options don't work.
How Does Your SIC Code Decide Whether You Need PAG-03 Coverage?
Once you have a primary SIC code, check whether it falls in one of the industrial categories covered by the stormwater rules. If it does, DEP's FAQ says you need to either get permit coverage or file for a No Exposure Certification. If it doesn't, you generally don't need industrial stormwater coverage, though DEP can still require a permit if it finds a facility is discharging pollutants. Our article on who needs a stormwater permit goes deeper on that general question.
A covered code is only the first of three questions. The second is whether any industrial materials or activities are exposed to rain and snow. If everything happens indoors or under roof, you may qualify for a No Exposure Certification instead of a permit, which DEP has to approve and which must be renewed every five years. Read more about what No Exposure means if that sounds like your site. The third question is where your stormwater goes. Facilities discharging to High Quality or Exceptional Value waters aren't eligible for PAG-03 or No Exposure and generally need an individual permit. Our guide on general, individual, and No Exposure permits explains how those paths differ. Local rules can also matter, especially if your site drains to a combined sewer, so it's worth confirming with your municipality or sewer authority.
A few activities are covered by description rather than by code. Hazardous waste treatment, storage, and disposal facilities, landfills that have received industrial waste, and steam electric power plants are covered by description in the federal rule, and DEP's FAQ confirms that a hazardous waste facility needs coverage even if its SIC code isn't on the list. Going the other direction, some coded industries aren't handled under PAG-03 at all. Mining and quarrying operations, for example, fall under DEP's mining program rather than PAG-03, which is worth knowing if you run a quarry alongside a concrete or asphalt plant.
Which PAG-03 Appendix Matches Your SIC Code?
PAG-03 is organized into sector appendices, labeled A through U, and your SIC code tells you which one applies. Each appendix sets out the monitoring parameters and best management practices for that type of industry, so the appendix determines what you'll sample for, not just whether you need a permit. The current PAG-03 took effect on March 24, 2023, and DEP added total nitrogen and total phosphorus monitoring to every appendix with that reissuance. Here's how the appendices line up, based on DEP's PAG-03 fact sheet and permit materials.
| Appendix |
Industry Sector |
Example SIC Codes |
| A |
Hazardous waste treatment, storage, or disposal |
4953 and others |
| B |
Primary metals |
3312-3317, 3321-3325 |
| C |
Landfills and land application sites |
4953 and others |
| D |
Timber products |
2421, 2448, 2491 |
| E |
Paper and allied products |
2611, 2621, 2652-2657 |
| F |
Chemicals and allied products |
2812-2899, 2911 |
| G |
Air transportation |
4512-4581 |
| H |
Steam electric generating facilities |
4911 |
| I |
Food and kindred products |
2011-2099, 2111-2141 |
| J |
Additional facilities not described elsewhere |
Various |
| K |
Salt storage and distribution sites |
Various |
| L |
Land transportation and petroleum terminals |
4011, 4212-4231, 5171 |
| M |
Asphalt paving, roofing materials, and lubricants |
2951, 2952, 2992 |
| N |
Glass, clay, cement, concrete, and gypsum |
3241, 3271-3275, 3281 |
| O |
Automobile salvage yards |
5015 |
| P |
Scrap and waste recycling |
5093 |
| Q |
Textiles, apparel, and leather products |
2211-2399, 3131-3199 |
| R |
Printing and publishing |
2711-2796 |
| S |
Rubber, plastics, and miscellaneous manufacturing |
3011, 3081-3089, 3991-3999 |
| T |
Leather tanning and finishing |
3111 |
| U |
Fabricated metal products |
3411-3499 |
Treat this as a map, not a substitute for the permit. The code ranges above are examples, and DEP can revise the permit or assign a facility to a different appendix if its activities fit better elsewhere. Always confirm your code against the current PAG-03 and its Notice of Intent instructions before you file. Once you know your appendix, our articles on PAG-03 stormwater sampling and benchmark values vs. effluent limits explain what those monitoring requirements look like in practice.
Common SIC Codes in Pennsylvania Industries and What They Mean for Stormwater
The appendix table shows the whole permit. In practice, most of the facilities we hear from fall into a handful of familiar industries. Here's what some common codes typically mean, along with a few that often surprise people because they're not covered. Confirm your own situation against the current PAG-03, since exposure, discharge location, and DEP's review all affect the final answer.
| SIC Code |
Industry |
What It Typically Means for Stormwater |
| 3273 |
Ready-mixed concrete |
Covered under Appendix N |
| 2951 |
Asphalt paving mixtures |
Covered under Appendix M |
| 3441 |
Fabricated structural metal |
Covered under Appendix U |
| 3089 |
Plastics products |
Covered under Appendix S |
| 2086 |
Bottled and canned soft drinks |
Covered under Appendix I |
| 5093 |
Scrap and waste materials |
Covered under Appendix P |
| 5015 |
Used auto parts (salvage yards) |
Covered under Appendix O |
| 4212-4231 |
Trucking |
Appendix L, but only for vehicle maintenance, equipment cleaning, and fueling areas |
| 1422 |
Crushed and broken limestone (quarries) |
Handled under DEP's mining program, not PAG-03 |
| 5051 |
Metals service centers |
Wholesale trade, often not covered |
| 7532 and 7538 |
Auto body and general auto repair shops |
Not on the covered list, so usually no PAG-03 |
| 5511 |
New and used car dealers |
Not on the covered list, so usually no PAG-03 |
The bottom half of that table is the part we wish more people knew. Warehouses, body shops, dealerships, quick-lubes, and most contractors probably don't need PAG-03 coverage at all, and we'd rather tell you that than see you pay for a permit you don't need. Concrete producers, on the other hand, are squarely covered, and our producer's guide to concrete plants and stormwater permits covers that industry in more depth.
What to Do If Your SIC Code Is Ambiguous for PAG-03
Sometimes two codes both seem to fit, your revenue is split close to evenly, or your operation doesn't look like anything in the manual. Start by reading the full SIC descriptions for each candidate code in OSHA's search tool, not just the titles. Then run the revenue test on the most recent year or two, since DEP looks at which activity brings in the most money. Write down which codes you considered, which one you chose, and why.
If you're still stuck, keep a few things in mind. DEP can assign a facility to an appendix based on similar activities even when the SIC code doesn't match exactly, and it can decide a different appendix fits better than the one on your NOI. If your code isn't listed but your work looks like a covered industry, DEP may still treat you as covered. PAG-03 also includes Appendix J for facilities DEP determines need coverage but that don't fit another appendix, and a facility that can't fit the general permit may need an individual permit instead. Rather than guess, you can ask DEP's Bureau of Clean Water directly at 717-787-5017 or RA-EPNPDES_Permits@pa.gov, or contact your regional office. Codes in tricky categories, like recycling operations that blur into manufacturing or sites that share space with a quarry, are worth a second opinion from someone who handles PAG-03 regularly.
What you shouldn't do is pick the code that avoids a permit just because it's convenient. If DEP later decides your primary activity is covered, you'll be catching up on coverage, a PPC Plan, and monitoring all at once. A documented, good-faith determination holds up much better. Our article on whether you can get a PAG-03 permit yourself can help you decide how much of this to handle in-house.
How RMA Helps With SIC Codes and PAG-03 Decisions
RMA is a family-run environmental consulting firm based in New Jersey, and we work with facilities across Pennsylvania on industrial stormwater. We can review your operations, help you land on a defensible primary SIC code, and tell you plainly whether you need PAG-03 coverage, qualify for a No Exposure Certification, or don't need either one. If you do need coverage, we can identify the right appendix, prepare your PPC Plan and Notice of Intent, and help with the sampling and reporting that follow. Our article on SWPPPs vs. PPC Plans for PAG-03 explains what that plan involves.
If a quick conversation shows you don't need a consultant, or don't need a permit at all, we'll tell you. There's no pressure and no obligation. You can call us, send an email, or fill out the form on our website. Whenever you're ready, reach out to RMA and we'll help you figure out where your facility stands.
