How DNREC Decides Which Delaware Facilities Need Industrial Stormwater Permit Coverage, and What to Do About It
If you're asking whether you need an industrial stormwater permit in Delaware, something probably prompted the question. Maybe DNREC sent you a letter. Maybe you're buying a property and an old permit file turned up in the diligence materials. Maybe your operation grew and now there's material sitting outside that used to live under a roof. Whatever started it, the businesses that end up in real trouble usually weren't ignoring the rules. They just never checked.
The good news is that Delaware's program is more manageable than it looks once you understand what the state is actually asking. Below we'll cover what the permit regulates, why your SIC code matters but doesn't decide anything on its own, what counts as exposure, the three ways a Delaware facility can handle coverage, what it costs, and what happens if you guess wrong. If you'd rather have someone look at your site and tell you where you stand, you can reach out to RMA and we'll give you a straight answer.
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TL;DR
In Delaware, industrial stormwater permits are run by DNREC under the state's own regulations, not by EPA's Multi-Sector General Permit. What decides whether you need coverage isn't your industry label, it's whether industrial materials or activities at your site are exposed to precipitation and whether that runoff leaves your property. If they are, you file a Notice of Intent and submit a stormwater plan with it; if nothing is exposed, you may qualify for a Conditional No Exposure Certification instead. Either way there's a $250 application fee and a $250 annual fee, and the real cost is the work behind the paperwork.
What a Delaware Industrial Stormwater Permit Actually Covers
An industrial stormwater permit regulates rain and snowmelt that touches industrial materials or activities at your site and then leaves the property. If water runs across a scrap pile, an uncovered dumpster, a leaking piece of equipment, or a fueling area and then heads for a ditch, a storm drain, or a stream, the state wants controls in place so it isn't carrying pollutants with it.
Delaware's version sits inside the Regulations Governing the Control of Water Pollution at 7 DE Admin. Code 7201, with industrial stormwater in Subsection 9.1. The state defines industrial activity as activity that results in the exposure of significant materials to precipitation, and significant materials as substances, products, or wastes that can contribute pollutants to runoff when stormwater contacts them. That definition is built around exposure, not around what your business calls itself.
There's one Delaware wrinkle that catches people who've dealt with stormwater in other states. Delaware law requires a permit for any discharge of pollutants to waters of the state, so the stormwater program applies to sheet flow as well as point source discharges. You don't need a pipe or an outfall for this to apply to you. Water running off the edge of your pavement and across the property line counts. For the broader background on how these permits work, our complete guide to NPDES and stormwater permits covers the national picture, and stormwater associated with industrial activity unpacks that specific phrase in more detail.
Why Delaware Isn't an MSGP State
This trips up a lot of people, including consultants who work across state lines, so it's worth being direct. Delaware does not operate under EPA's Multi-Sector General Permit. EPA can authorize a state to run the NPDES program itself, and Delaware received that authority in April 1974. Since then, DNREC has issued and enforced stormwater permits here under state regulations.
Why does the distinction matter? Because the MSGP has its own sector structure, benchmark tables, and deadlines, and none of those are what DNREC will hold you to. Build your program around EPA's MSGP and you'll be working from a document that doesn't govern your facility. Florida really does run an MSGP-style program, New Jersey has its own 5G2 basic industrial permit, North Carolina runs a different set of general permits entirely, and Delaware runs Subsection 9.1. Same federal backbone, genuinely different paperwork.
How SIC Codes Fit Into Delaware Industrial Stormwater Permit Requirements
SIC stands for Standard Industrial Classification, the government's old system for categorizing what a business does. Certain codes are called out in the stormwater regulations as operations that typically generate contaminated runoff. The Delaware Notice of Intent form asks you to list up to four four-digit SIC codes in descending order of significance, plus four letter codes for activities that don't map cleanly: HZ for hazardous waste treatment, storage, or disposal, LF for landfills and land application sites, SE for steam electric power generating facilities, and TW for treatment works handling domestic sewage or sludge.
Here's the part worth internalizing. Your SIC code puts you on the radar. Your actual site conditions decide whether you need a permit. A warehousing code by itself may not trigger anything. That same warehouse doing forklift maintenance in the back lot, storing drums outside, and running an uncovered waste compactor is a different conversation entirely.
It works in the other direction too. We regularly find facilities carrying a code inherited from a previous owner or a line of business they exited a decade ago. If it doesn't describe what happens on the property today, fix it, because that code is one of the first things a regulator looks at. The NOI also asks whether you're subject to SARA Title III Section 313, the toxic chemical release reporting program. If you're unsure how to answer, our guide to community right-to-know reporting in Delaware is a good place to start, since the same chemical inventory usually drives both.
What Counts as Exposure Under Delaware's Industrial Stormwater Rules
This is where most of the real disagreement lives. People hear "industrial stormwater" and picture a pipe discharging into a creek. What regulators are looking for is much more ordinary.
Delaware's No Exposure Certification form spells it out better than any summary could, because it asks you to certify that none of eleven conditions exist at your site. Those include exposed industrial materials used, stored, or cleaned on site, residuals on the ground or in storm inlets from spills and leaks, materials from past industrial activity, material handling equipment other than adequately maintained vehicles, materials during loading and unloading, products stored outdoors, materials in exposed drums, barrels, and tanks, materials handled on roads or railways you own, waste material other than waste in covered non-leaking containers, application or disposal of process wastewater, and residue from roof stacks and vents.
Read that list against your own yard and the picture usually resolves fast. One uncovered dumpster of industrial waste is enough, or one leaking forklift parked outside. And "temporary" doesn't buy you much, because the standard is whether exposure exists now or in the foreseeable future. If some of your outdoor water is process water rather than stormwater, that's a separate and often bigger issue, covered in stormwater versus process water.
Delaware Industries That Most Often Need Industrial Stormwater Permits
Some operations turn up in Delaware's industrial stormwater program far more often than others, following the state's geography and industrial base.
Manufacturing is the broadest category, especially metals, chemicals, plastics, food processing, fabrication, and coatings, where raw material storage, loading areas, and outdoor equipment create exposure even when production happens indoors. Concrete plants, asphalt facilities, and aggregate yards are almost always in the program, since exposed material is fundamental to how they operate, and we've written a full producer's guide to concrete plants and stormwater permits for that industry.
Given Delaware's river frontage and port activity, marine terminals pick up obligations tied to fueling, cargo handling, and vessel maintenance. Truck yards, bus depots, and fleet shops show up constantly, usually because of fueling islands and outdoor repairs. Recycling and scrap operations draw the most scrutiny of any sector, since exposed metal and mixed material carry high contamination potential. Public works yards, fuel terminals, and landfills round out the list. Size matters less than people expect. We've seen small operations need coverage over a single exposure problem, and larger sites qualify for exclusions because everything is genuinely under roof.
The Three Ways to Handle Delaware Industrial Stormwater Permit Coverage
Delaware gives facilities three paths, and picking the right one is most of the decision. You can file a Notice of Intent for coverage under the general permit program, file a Conditional No Exposure Certification if nothing is exposed, or apply for an individual permit. Our article on general, individual, and no exposure permits walks through how these compare nationally.
The Notice of Intent path is the most common, and it holds a detail that surprises people who've permitted facilities elsewhere: new facilities, facilities currently covered by an individual permit, and existing facilities without NPDES coverage must prepare and implement a Storm Water Plan before submitting the NOI, and that plan has to be submitted with the form. You don't apply first and write the plan later. That single requirement is the main reason Delaware timelines run longer than facility managers expect.
The plan is what most of the industry calls a SWPPP, and DNREC publishes a template along with EPA's sector fact sheets on its industrial stormwater program page. If you're weighing whether to write it in house, developing your own SWPPP and what a SWPPP actually contains are both worth reading first. The NOI form also asks for your receiving water body or public MS4, your watershed, and your latitude and longitude to six decimal places, and DNREC requires NOIs to be submitted digitally.
What Delaware's No Exposure Certification Actually Requires
Plenty of facilities assume they need a full permit when they don't, and the No Exposure route is why. Filing a Conditional No Exposure Certification excludes a facility from the monitoring requirements at Subsection 9.1.4 and the stormwater plan requirements at 9.1.5. No sampling, no plan, no benchmark chasing. For a site that genuinely keeps everything indoors, that's a real difference in ongoing cost.
It's conditional for a reason. Answering yes to any one of the eleven questions disqualifies you, the certification has to be resubmitted at least every five years, and you have to let DNREC, or the local MS4 operator you discharge into, inspect and confirm the condition, with those reports public on request. If something ends up outside, you have to get permit coverage before stormwater discharges.
One question on the form is worth understanding first. DNREC asks whether you paved or roofed over a formerly pervious area in order to qualify, and how much. Answering yes doesn't disqualify you, but the state may use it in deciding whether your discharges are likely to affect water quality, in which case you could be required to get coverage anyway. Construction stormwater isn't eligible for the exclusion at all. For the general concept without the Delaware specifics, we've covered what non-exposure means in plain terms.
What a Delaware Industrial Stormwater Permit Costs
There are two separate numbers here, and mixing them up is where confusion starts. The first is what Delaware charges. A $250 non-refundable fee is due for initial first-time coverage, and after that a $250 annual permit fee is billed on or after July 1 each fiscal year. If you're renewing and current on the annual fee, you don't need to include the application fee again. The same structure applies to the No Exposure Certification. That's the state's cost, and it's modest.
The second number is what it costs to do the work, and that varies a lot more. A stormwater plan for a simple site with one outfall and a handful of materials is a very different job from a multi-building facility with several discharge points and a compliance history to untangle. Then there's the ongoing side: inspections, sampling events, lab fees, training, and reporting. Our article on what a stormwater permit costs gets into the variables in more depth.
Rather than guess, use the pricing calculator below for a ballpark on professional help with your Delaware stormwater permitting. It takes a minute, no email required, and nobody calls you afterward. To be clear about what it estimates, that's the cost of bringing RMA in to do the work, not the cost of the permit itself. You can also browse our full set of service pricing calculators if you've got other compliance areas on your plate.
Common Misconceptions About Delaware Industrial Stormwater Permits
We hear the same handful of objections constantly, and each has a reasonable-sounding logic that doesn't survive contact with the regulations.
"We've been here twenty years and nobody's ever said anything." That happens more than you'd think, and it isn't evidence of compliance. It usually means nothing has prompted a look yet, whether that's a complaint, an inspection nearby, an operational change, or an aerial review.
"We don't discharge into a stream." Storm drains count. Ditches count. Municipal systems count. And in Delaware, sheet flow off your pavement counts too, which is broader than a lot of states.
"We're too small," and its cousin "we're mostly indoors." Size rarely decides it, and mostly isn't the test. The test is whether anything on that eleven-item list is exposed.
"Our landlord handles that." Sometimes true, often not, and leases are frequently silent on who holds the permit and who does the sampling. Worth resolving in writing before an inspector asks, not after. For more patterns like these, common NPDES problems and how we fix them covers what we run into most.
What Happens If You Need a Delaware Stormwater Permit and Don't Have One
If DNREC determines your facility should have had coverage and doesn't, you're looking at a notice of violation and a compliance schedule, and possibly a formal enforcement action. Unpermitted discharge of pollutants to waters of the state is a Clean Water Act issue as well as a state one, and the federal civil penalty ceiling runs into the tens of thousands of dollars per day under the inflation-adjusted table at 40 CFR Part 19.
In practice, the penalty usually isn't the expensive part. The expensive part is doing eighteen months of work in six weeks. You're writing a stormwater plan, filing an NOI, setting up sampling, training staff, and fixing site conditions at once, on the agency's timeline instead of your own. Everything costs more when it's urgent, and we've written about the hidden costs of non-compliance because the fine is often the smallest line item.
There's a transactional angle too. An unpermitted discharge that surfaces during a sale or refinance can hold up a closing, and buyers price that risk conservatively. Finding it yourself, with no deadline attached, is a much better version of this problem.
How RMA Helps Delaware Facilities With Industrial Stormwater Permits
We've been doing NPDES and industrial stormwater permitting since 1992, and we work with facilities throughout Delaware on all of it: applicability evaluations, SIC code reviews, site walkthroughs, stormwater plan development, NOI and No Exposure filings, sampling programs, stormwater training, inspections, and dealing with DNREC when questions come up.
We'll also tell you when you don't need us. Some facilities can handle this themselves, and if yours is one of them, we'd rather say so and point you at the right forms. To start on your own, walk your site against that eleven-item list, pull your SIC code, and look at where water actually leaves your property. That gets you most of the way there. It gets harder at writing the plan, building a defensible sampling program, and working out an applicability disagreement with the state, which are the parts most facilities hand off. For a sense of what's realistic in house, getting a stormwater permit yourself is an honest look at it.
If you'd like us to take a look, you can call us, email us, or fill out the form on our contact page. There's no pressure and no obligation. We'll help you figure out where you stand, tell you honestly whether you need coverage, and you can decide what to do from there.
