Colorado Construction Stormwater Permit (CDPS COR400000): The Complete Guide

If you are disturbing an acre or more of soil anywhere in Colorado — or a smaller parcel that is part of a larger common plan of development — you need construction stormwater permit coverage before the first shovel of dirt moves. In Colorado, that permit is the CDPS Construction General Permit COR400000, issued by the Colorado Department of Public Health and Environment (CDPHE) Water Quality Control Division. It is Colorado's version of the federal NPDES Construction General Permit, delegated to the state under the Clean Water Act, and it is the single most common permit trigger on a Colorado land-development project.

The mechanics will look familiar if you've worked stormwater permits in other states: coverage before disturbance, a written plan, inspections through construction, and a termination filing at final stabilization. But Colorado runs its own portal and, notably, its own vocabulary — the plan you'd call a SWPPP anywhere else is a SWMP here. That difference trips up more out-of-state engineering teams than almost anything else in the Colorado permitting stack.

What is CDPS COR400000?

COR400000 is Colorado's Construction General Permit under the state's Colorado Discharge Permit System (CDPS) — the state-delegated equivalent of the federal NPDES program. It authorizes the discharge of stormwater associated with construction activity, and it is the permit that applies to essentially every site-civil project in the state that crosses the disturbance threshold. CDPHE's Water Quality Control Division administers the permit, reviews applications, and conducts compliance inspections.

When do I need coverage under COR400000?

You need CDPS construction stormwater coverage if your project will disturb one acre or more of soil, or if it is part of a larger common plan of development or sale that will collectively disturb one acre or more — even if your individual phase is smaller. This mirrors the federal ≥1-acre / common-plan trigger used nationwide. A four-lot subdivision built out in half-acre phases under one master plan still needs coverage, because the phases are evaluated together, not individually.

Coverage must be obtained, and the site's SWMP substantially prepared, before any soil disturbance begins. Starting grading ahead of certification is a common and easily avoidable compliance finding.

Why does Colorado call it a SWMP instead of a SWPPP?

Because that's simply the term COR400000 uses. Federally, and in most states — including Texas under TXR150000 and Florida under the FDEP CGP — the site-specific stormwater document is called a Stormwater Pollution Prevention Plan, or SWPPP. Colorado's permit requires the same category of document but calls it a Stormwater Management Plan (SWMP), with its own enumerated list of required elements under COR400000. The engineering content overlaps heavily with a SWPPP — site map, BMPs, inspection schedule, stabilization criteria — but the organization and the label are Colorado-specific. For a full side-by-side comparison, see SWPPP vs. SWMP: What's the Difference?. If your firm also works in Texas or Florida, do not hand a reviewer a document labeled SWPPP for a Colorado project — it signals unfamiliarity with the program even where the content is compliant.

How do I apply for COR400000 coverage?

Colorado's construction stormwater application runs through Colorado Environmental Online Services (CEOS), CDPHE's e-permitting portal. The general sequence looks like this:

1. Prepare the SWMP — site description, receiving waters, BMP selection, inspection and maintenance schedule, and final stabilization criteria, built around COR400000's required-elements list.
2. Submit the application through CEOS — including site location, disturbed acreage, and the responsible operator(s).
3. Receive certification — CDPHE issues permit certification and a permit number specific to the site.
4. Keep the SWMP on site — available to CDPHE inspectors and, in most cases, to the local jurisdiction's own stormwater/erosion reviewer.
5. Begin disturbance only after certification is in hand.

Multiple operators on a single site — common on larger subdivisions with a master developer and multiple builders — each need to evaluate their own permit obligations; CDPHE's permit structure addresses shared and phased responsibility, so get this sorted at the entitlement stage rather than after grading starts.

What inspections does COR400000 require?

Once coverage is active, the SWMP has to be implemented and kept current, and the site has to be inspected on a regular schedule through construction — the permit specifies the required inspection frequency and documentation. In practice this means:

• Routine site inspections checking BMP condition, sediment tracking, and discharge points.
• Inspection reports kept with the SWMP and available on request.
• BMP repairs, replacements, and SWMP updates documented as the site changes — new phases, new discharge points, contractor changes.
• Additional attention after significant precipitation events, consistent with the permit's inspection triggers.

CDPHE conducts its own compliance inspections and can issue findings independent of the contractor's self-inspection program — a thin or stale SWMP is one of the fastest ways to draw a notice of violation.

How do I terminate COR400000 coverage?

Coverage ends with a Notice of Termination (NOT) filed once the site reaches final stabilization — vegetative cover established or other permanent stabilization measures in place, consistent with the permit's stabilization criteria, and temporary BMPs removed. Filing the NOT too early, before stabilization criteria are actually met, is a common self-inflicted compliance problem; treat it the same way you would a federal CGP termination — supported by inspection records showing stabilization was achieved before you filed.

COR400000 at a glance

How does COR400000 interact with local Colorado jurisdictions?

COR400000 is a state permit, but most Colorado land-development sites also answer to a local grading, erosion-control, or drainage review — Denver, Colorado Springs, Aurora, Fort Collins, and Lakewood all run their own site-development and stormwater criteria on top of the state permit. See Denver's grading and stormwater permit guide and Colorado Springs' land development permit guide for how the local layer stacks with COR400000. The state permit does not replace local approval, and local reviewers frequently ask to see the certified SWMP as part of their own submittal package. For the full picture of how Colorado's site-civil permits fit together, start with the Colorado site-civil permitting guide.

This two-layer structure — state discharge permit plus local erosion/grading review — is the norm rather than the exception in Colorado, and it means a single project can have two separate stormwater-adjacent submittals moving on two separate clocks. A common sequencing mistake is treating the local grading permit as the pacing item and leaving CEOS registration until grading approval is imminent; because CDPHE certification has to be in hand before disturbance, and because most local jurisdictions won't release a grading or building permit without proof of state coverage, it's worth submitting the CEOS application as soon as the SWMP is far enough along to support it, rather than waiting on the local review to fully resolve first.

What should a Colorado SWMP actually contain?

Beyond the general BMP-and-inspection framework shared with SWPPPs nationwide, a COR400000-compliant SWMP should be built directly against the permit's own enumerated element list rather than a generic template. At minimum, expect it to document: a site description and construction sequence; a description of potential pollutant sources tied to each phase of work; the specific structural and non-structural BMPs selected for each source, keyed to the site map; a description of the receiving waters and any water-quality-sensitive downstream conditions; the inspection schedule and responsible personnel; and the specific stabilization criteria that will trigger the Notice of Termination. Reviewers at CDPHE, and local erosion-control staff who see the SWMP as part of a grading submittal, are looking for a plan that reads as site-specific rather than boilerplate — generic language copied from a template with the project name swapped in is one of the more common reasons a SWMP gets kicked back for revision.

Colorado's construction stormwater program is procedurally close to the federal model most engineers already know, with two things worth remembering: CEOS is the portal, and the plan is a SWMP, not a SWPPP. Get the vocabulary and the element list right the first time, and COR400000 moves through review about as smoothly as any NPDES-delegated program in the country.