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Montana

The stormwater permit for construction in Montana

Montana runs its own NPDES programme, so a state issued construction general permit governs. Below is what our engine can say about it, and where we have not read that permit, what it will not say.

Governing permit

General Permit for Storm Water Discharges Associated with Construction Activity (MTR100000)

Issued by
Montana Department of Environmental Quality (Montana DEQ)
Permit number
MTR100000
Version determined against
as published by the state agency
Read the permitMontana Department of Environmental Quality (Montana DEQ)

Who may prepare the plan

A credentialed preparer is required

Montana requires a credentialed preparer. Treat the generated document as a complete draft for that person to review, adopt and sign. It is not by itself a compliant filed plan.

Qualifying routes

  • Montana DEQ-approved SWPPP Preparer certification

Credential: Part 3.2 requires that 'SWPPP Preparers and Administrators must obtain certification from a course approved by DEQ and maintain a valid certification', valid no more than three years from the date of certification. Generated SWPPPs are drafts for a certified preparer to review, amend and sign. The preparer requirement was found during the jurisdiction registry pass but the exact permit clause was not captured, so this is marked unverified. We still apply the gate, because under-claiming a credential requirement is the safe direction of error.

No permit section cited. Confirm this with your permitting authority.

Does a site in Montana need coverage

Worked for a one acre site as a reference point. Change the acreage in the tool below and the answer, and its reasoning, change with it.

Coverage

Permit coverage required

Verified

The project disturbs 1 acres, at or above the 1 acre threshold, so it needs permit coverage.

Determined against dataset version 2026-07-19.

Read these before you act on the answer

  • We have identified General Permit for Storm Water Discharges Associated with Construction Activity (MTR100000) as the governing permit but have not loaded its requirements. The requirements below are not shown because we will not substitute the federal permit's rules for a state's. Confirm with Montana Department of Environmental Quality (Montana DEQ).
  • Montana requires a credentialed preparer. Treat the generated document as a complete draft for that person to review, adopt and sign. It is not by itself a compliant filed plan.
  • Basinwise does not perform the physical site inspections the permit requires. Those must be carried out on site by a qualified person.
How this answer was reached, step by step
  1. 1

    Coverage threshold

    The project disturbs 1 acres, at or above the 1 acre threshold, so it needs permit coverage.

    VerifiedPart 1.1.2Source
  2. 2

    Permitting authority

    Montana. The state runs its own programme under MTR100000.

  3. 3

    Preparer credential

    Montana requires a credentialed preparer. Treat the generated document as a complete draft for that person to review, adopt and sign. It is not by itself a compliant filed plan.

What to do next

  1. 1. Confirm the governing permit. Read General Permit for Storm Water Discharges Associated with Construction Activity (MTR100000) directly. It is linked above, and it is the document an inspector will hold you to. Montana Department of Environmental Quality (Montana DEQ)
  2. 2. Settle the preparer question before you draft. Getting this wrong costs a redraft at best. The detail is on the credential page for this state. Preparer credential in Montana
  3. 3. Screen the site. Run the real acreage and receiving water facts through the tool below. You get the inspection frequency, the stabilisation deadlines and the filing path with the permit section behind each.
  4. 4. Read the requirements in full. SWPPP requirements in Montana

Screen a Montana site now

Runs in your browser. Nothing about the site is transmitted.

Screen your site

Runs in your browser

Total land disturbance over the whole project, including staging and access. This decides whether you need a permit at all.

Optional. If you phase the work, the most that will be disturbed at once. Leave blank if the whole site is open together. The stabilisation deadline turns on this figure, not the total.

A half acre lot inside a 40 acre subdivision is covered even though the lot alone is under the threshold. This is the most commonly missed trigger in the permit.

Receiving water and site conditions(optional, but they change the inspection frequency)

May allow a reduced inspection frequency during the seasonally dry period.

EPA keeps permitting authority in Indian country even inside a state that runs its own programme.

No account, no card, nothing transmitted.

What people ask about the Montana construction stormwater permit

Do I need a stormwater permit for a construction site in Montana?

Permit coverage is triggered at one acre of land disturbance, and below one acre if the project is part of a larger common plan of development or sale that will ultimately disturb an acre or more. The project disturbs 1 acres, at or above the 1 acre threshold, so it needs permit coverage.

Who issues the construction stormwater permit in Montana?

Montana Department of Environmental Quality (Montana DEQ) issues General Permit for Storm Water Discharges Associated with Construction Activity (MTR100000).

Does Montana require a qualified preparer for the plan?

Montana requires a credentialed preparer. Treat the generated document as a complete draft for that person to review, adopt and sign. It is not by itself a compliant filed plan.

Keep the record Montana will ask you for

The screening is free. Holding the written plan and the retained inspection log is what the permit actually demands.

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