Is the threshold about total site area or disturbed area?

Disturbed area is what these clauses measure, and it is what the questionnaire asks for. A 40-acre parcel with 1.5 disturbed acres is a 1.5-acre project for this purpose.

What is a larger common plan of development?

A site that is one piece of a bigger scheme — a lot inside a subdivision, a phase of a larger build. It can pull a sub-acre site into permit coverage, which is why the under-one-acre answer is "usually not" rather than "no".

What acreage thresholds change SWPPP requirements?

Below one disturbed acre federal permit coverage is usually not required at all; above that, the thresholds that change who may write the plan are state-specific — 2 acres in South Carolina, 5 acres in Tennessee and Utah, 20 acres in Oregon, and 5,000 square feet in New Jersey.

Source: SwpppDraft 50-state preparer-requirement table, from a scan of all 50 construction general permitsVerified 2026-08-03

The two universal edges

Below one disturbed acre, federal construction general permit coverage is usually not required at all unless the site is part of a larger common plan of development. Check whether you need a SWPPP before you pay for one.

Above five disturbed acres you are outside the 1–5 acre range this tool was built for. Several states change their preparer requirements above five acres, so re-read your state permit before relying on a self-prepared plan.

The lines that fall inside the band

South Carolina's 2-acre line cuts the 1–5 acre band in half: at or below it a sketched plan with no professional seal is enough, above it the plan must be prepared and stamped by one of the licensed disciplines the permit lists. Tennessee's qualification requirements start above five acres, which is why a small Tennessee site is self-serve today — and why its 2026 permit re-issue is worth watching. New Jersey's trigger is 5,000 square feet, far below one acre, so it covers the whole band.

Questions people ask

Is the threshold about total site area or disturbed area?: Disturbed area is what these clauses measure, and it is what the questionnaire asks for. A 40-acre parcel with 1.5 disturbed acres is a 1.5-acre project for this purpose.
What is a larger common plan of development?: A site that is one piece of a bigger scheme — a lot inside a subdivision, a phase of a larger build. It can pull a sub-acre site into permit coverage, which is why the under-one-acre answer is "usually not" rather than "no".

The states this question turns on

South Carolina SWPPP requirements — South Carolina requires a licensed engineer, landscape architect or Tier B land surveyor to stamp the plan only above 2 disturbed acres; at or below 2 acres a sketched plan with no seal is accepted.
Tennessee SWPPP requirements — Tennessee's preparer qualification requirements apply only to sites disturbing more than five acres; at or below five acres they do not apply.
Utah SWPPP requirements — Utah requires a qualified SWPPP writer for a 1–5 acre site only when perennial surface water sits within 50 feet or the site has a slope of 70% (35 degrees) or steeper.
Oregon SWPPP requirements — Oregon small sites can self-prepare by default; a stamp by a CPESC, CPSWQ, PE, RLA or CEG is required only when the site disturbs 20 acres or more, when a non-standard buffer compliance option is used because water is within 50 feet, or when an engineered sediment basin or erosion management plan is built.
New Jersey SWPPP requirements — New Jersey requires the engineering items of the soil erosion and sediment control plan to be sealed by a licensed New Jersey engineer or architect, triggered above 5,000 square feet.

All 50 states, in one table

What we are, and what stays your responsibility

SwpppDraft is a document generation tool. It does not provide engineering services, legal services, or compliance consulting, and no engineer or attorney reviews what it produces.
Everything in the document is built from the site facts you enter. Checking that those facts are right, and that the resulting plan fits your project, is yours to do.
We do not file anything on your behalf, we do not certify or endorse your compliance, and we accept no liability for what happens when you use the document.
State-level requirements carry the date we verified them. County and city rules are not covered — some local jurisdictions require a licensed preparer even where the state does not, and you have to check that yourself.
When the product opens, our total liability will be capped at the amount you paid us. Today that amount is zero, because nothing is for sale.