The single biggest permitting question on any land-development project is deceptively simple: how much can we disturb before we need a permit? The answer has a federal floor, a state layer on top of it, and — almost always — a local layer on top of that. Miss any one of the three and you end up either scrambling for coverage mid-earthwork or over-engineering a plan the regulator never asked for.
Here is how the three layers actually stack, and how the tier-1 states — Texas, Florida, and Colorado — compare.
What is the federal land disturbance threshold?
The federal threshold is 1 acre of disturbance, the trigger for NPDES Construction General Permit (CGP) coverage under the Clean Water Act. Any project that disturbs 1 acre or more — or that is part of a larger common plan of development that totals 1 acre or more — needs CGP coverage: a stormwater plan (SWPPP or, in Colorado, a SWMP) and a Notice of Intent (NOI) filed before soil disturbance begins, followed by a Notice of Termination (NOT) at final stabilization. Most states are NPDES-delegated and run their own version of this permit rather than EPA administering it directly.
This 1-acre figure is a floor, not a ceiling. States and localities are free to set — and routinely do set — lower thresholds of their own. See what is a grading permit for how the local layer works in practice.
How do states and localities set lower thresholds?
States implement the federal CGP through their own delegated program, and many break the acreage into tiers that change the paperwork burden rather than the trigger itself — Texas, for example, splits its CGP into a small-construction tier and a large-construction tier at the 5-acre mark, both of which still require a SWPPP starting at 1 acre. Localities layer a separate grading or land-disturbance ordinance on top of that, and local thresholds are frequently set well below 1 acre, especially where environmental overlays (floodplains, aquifer recharge zones, steep-slope districts) are in play.
The practical result: a site can be well under the federal 1-acre CGP trigger and still need a local grading permit, and a site well over 1 acre in a jurisdiction with strict overlays can face review requirements far more detailed than the state stormwater permit alone would suggest.
What counts as a "common plan of development"?
A common plan of development is the anti-fragmentation rule that keeps developers from evading the 1-acre CGP trigger by dividing one project into several sub-acre phases sold or built separately. If multiple smaller disturbances are part of a larger plan — the same parcel, the same developer, phased construction, a shared plat — the acreage is aggregated for purposes of the CGP trigger, even if no single phase crosses 1 acre on its own. A four-lot subdivision built in quarter-acre phases over several years is still one common plan of development at 1+ acres total, and still needs CGP coverage.
The same logic applies even when phases have different owners on paper — a developer who plats a parcel and sells sub-acre lots to separate builders under one overall development plan hasn't necessarily escaped the aggregation rule just because the disturbance is now split across different permittees. Anyone relying on lot splits or ownership changes to stay under 1 acre should confirm that reading with the regulating agency before relying on it, since the common-plan-of-development test looks at the plan, not the deed.
How do the thresholds compare in Texas, Florida, and Colorado?
All three tier-1 states use the same federal 1-acre floor for stormwater CGP coverage, but the programs built on top of it differ in structure and terminology.
| State | Program | Stormwater trigger | Notes |
|---|---|---|---|
| Texas | TCEQ TPDES Construction General Permit (TXR150000) | 1 to <5 acres = small construction; ≥5 acres = large construction | SWPPP required at 1 acre; coverage obtained via TCEQ STEERS ePermits before disturbance; a low-rainfall-erosivity waiver may apply to some small sites |
| Florida | FDEP Construction Generic Permit (CGP) | ≥1 acre | SWPPP + NOI required; land development sites are also frequently subject to the Environmental Resource Permit (ERP), which bundles stormwater quantity/quality with wetlands — ERP and FDEP CGP thresholds are separate and depend on project type/location |
| Colorado | CDPHE CDPS Construction General Permit (COR400000) | ≥1 acre (or part of a larger common plan) | Requires a SWMP (Stormwater Management Plan) rather than a SWPPP; applied for via Colorado Environmental Online Services (CEOS) |
See the TPDES TXR150000 guide and the CDPHE COR400000 guide for the full mechanics of each state's stormwater permit.
What local grading thresholds apply on top of state stormwater thresholds?
Local grading or land-disturbance ordinances set their own thresholds independent of the state CGP, and they are frequently lower than 1 acre. A city with an environmental overlay — a floodplain, a steep-slope district, an aquifer recharge zone — can require a grading permit and full site-plan review on a fraction of an acre. Austin's Critical Water Quality Zones and Edwards Aquifer Recharge/Contributing Zone are a well-known example of a local/regional trigger that sits well below the general acreage rule of thumb. Because these thresholds are set ordinance by ordinance, there is no single number that applies statewide — check the specific jurisdiction before assuming a small site is exempt.
Does crossing the tier matter, or just the 1-acre trigger?
In Texas, yes — the tier changes the paperwork, not just the requirement to have a SWPPP. Small construction sites (1 to <5 acres) and large construction sites (≥5 acres) both need TPDES coverage and a SWPPP, but the large-construction tier generally carries more detailed inspection and documentation expectations. Florida's layering works differently: crossing 1 acre triggers the FDEP Construction Generic Permit regardless of size, while the separate Environmental Resource Permit turns on project type and location rather than a single acreage line, which means a sub-acre project can still need an ERP if it affects wetlands or exceeds a water-management district's stormwater criteria. Colorado's COR400000 tiers are similarly acreage-driven above 1 acre, but the deliverable is a SWMP rather than a SWPPP throughout — a naming difference explored in SWPPP vs. SWMP.
What happens if a site exceeds a threshold without the required coverage?
Exact enforcement mechanics vary by regulator and jurisdiction, but the general pattern is consistent: a site that disturbs ground above the applicable federal, state, or local threshold without the required permit or coverage is out of compliance the moment disturbance begins, not just when it's discovered. That typically exposes the operator to a stop-work order, potential penalties under the Clean Water Act (for uncovered stormwater disturbance) or the local ordinance (for ungraded/unpermitted earthwork), and a scramble to retroactively document conditions the regulator would otherwise have reviewed in advance. Because the common-plan-of-development rule aggregates phased work, "we didn't think this phase counted" is one of the most common ways sites end up out of compliance without anyone intending to cut a corner.
How should multi-state teams track these thresholds?
The safest operating discipline for a firm working across Texas, Florida, and Colorado is to treat the 1-acre federal trigger as the baseline check and then run two additional checks for every site: the state program's own tiering (Texas's 5-acre split, Florida's ERP overlay, Colorado's SWMP requirement) and the local grading ordinance's independent threshold. Building a per-jurisdiction checklist once, rather than re-deriving thresholds project by project, is what keeps a multi-state pipeline from missing a permit late in design — particularly on phased subdivisions, where the common-plan-of-development rule means the threshold check has to be run against the whole plan, not just the current phase.