When You Need Both CGP & MSGP — Plus the SPCC Threshold
A single facility can require a construction CGP and an industrial MSGP at the same time — separate NOIs, separate SWPPPs, separate compliance obligations. Add a third requirement, the SPCC plan, once aggregate oil storage reaches 1,320 gallons. This is the compliance gap operators miss most often: assuming one permit covers the other.
Three Common Dual-Requirement Scenarios
Construction at an Active Industrial Facility
MSGP + CGPA manufacturing plant undergoing an expansion that disturbs 3 acres needs MSGP coverage for the ongoing industrial stormwater discharges from facility operations AND CGP coverage (NMR100000 in NM) for the construction activity. Both SWPPPs must exist and be maintained — the construction SWPPP covers the earthwork, the industrial SWPPP covers ongoing operations. They are separate documents with separate NOIs and separate compliance obligations.
Construction Project With On-Site Fuel Storage
CGP + SPCC planA large construction project with a 1,000-gallon diesel tank plus fuel in equipment sumps and generators may collectively exceed the SPCC aggregate oil-storage threshold of 1,320 gallons. That triggers a Spill Prevention, Control, and Countermeasure (SPCC) plan — a third, separate plan — in addition to the CGP for the land disturbance. The SPCC plan is not the MSGP; it is its own federal requirement under 40 CFR 112.
Industrial Facility Undergoing Demolition With Earthwork
CGP (MSGP terminating)A facility being demolished with 2+ acres of earthwork needs CGP coverage for the construction activity. If the facility previously held MSGP coverage and industrial operations have ceased, the MSGP may be eligible for termination — but not until industrial activity has fully stopped and no further industrial stormwater discharges will occur.
Decision Tree: Which Permits Do You Need?
Step 1
Is your project disturbing 1 acre or more of land (or part of a larger common plan that will)?
Yes → You need CGP coverage (NMR100000 in NM). Continue to Step 2.
—No → No CGP needed for disturbance. Continue to Step 2.
Step 2
Does the site involve ongoing industrial operations that discharge stormwater to waters of the U.S. in a covered MSGP sector?
Yes → You need MSGP coverage. Continue to Step 3.
—No → No MSGP needed. Proceed with the CGP alone (if Step 1 was yes).
Step 3
Did both Step 1 and Step 2 result in "yes"?
Yes → You need both permits. Maintain two separate SWPPPs and file two NOIs.
—No → Proceed with the applicable single permit.
Step 4
Does aggregate on-site oil/fuel storage reach or exceed 1,320 gallons?
Yes → You also need an SPCC plan under 40 CFR 112 — separate from both stormwater permits.
—No → No SPCC plan required on the storage basis (re-check if storage increases).
One Permit Does Not Satisfy the OtherMaintaining only a construction SWPPP while running industrial operations — or assuming an industrial SWPPP covers your earthwork — leaves a coverage gap that EPA and NMED can enforce against independently. When in doubt, have applicability reviewed before ground disturbance or facility startup.
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Frequently Asked Questions
Can a single facility really need two stormwater permits at once?
Yes — this is the scenario operators most often miss. The CGP covers temporary construction activity and the MSGP covers permanent industrial stormwater discharges. A construction project at an active industrial facility requires both simultaneously: two NOIs, two SWPPPs, and two sets of inspection and reporting obligations. One does not satisfy the other.
What is the SPCC threshold and how is it different from a SWPPP?
The Spill Prevention, Control, and Countermeasure (SPCC) rule under 40 CFR 112 applies when a facility's aggregate aboveground oil storage capacity is 1,320 gallons or more (counting tanks, drums, generators, and equipment sumps of 55 gallons or larger). An SPCC plan addresses oil-spill prevention and response and is entirely separate from a stormwater SWPPP — a facility can need a CGP SWPPP, an MSGP SWPPP, and an SPCC plan all at once.
Are the NOI processes the same for CGP and MSGP?
No. In New Mexico the construction CGP NOI is submitted to the permit authority and, in most states, you cannot start land disturbance until coverage is granted. The MSGP NOI is submitted to EPA through the NPDES electronic reporting system, and coverage typically begins about 7 days after submission for most sectors. When a new MSGP issues, there is a defined submission window — usually around 90 days — to file a new NOI under the new permit.