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
- Effective
- 2023-01-01
- Expires
- 2027-12-31
Who may prepare the plan
A credentialed preparer is requiredMontana 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
Confirmed by direct read of the full MTR100000 permit (effective 1/1/2023, expires 12/31/2027, current as of Aug 2026). Part 3.2 requires DEQ-approved course certification for both SWPPP Preparers and Administrators, valid no more than 3 years. No acreage threshold gates this requirement — it applies to every site covered under the General Permit. No PE stamp/seal requirement exists anywhere in the permit.
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
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
- Requirements below are what we have read and cited directly from General Permit for Storm Water Discharges Associated with Construction Activity (MTR100000), not the federal CGP. A category we have not yet transcribed from this permit is omitted here rather than assumed to match EPA's rule.
- MT's General Permit has no arid/semi-arid or drought-reduced inspection frequency provision, omitted rather than invented. MT also has no fixed numeric buffer distance around state waters; the permit only requires a qualitative 'natural buffer'. No acreage-tiered stabilization completion deadline table exists; a state-specific id was created instead. No fixed-day NOI-before-construction-start requirement or fixed-day NOT-after-completion requirement is specified (both event-triggered). No numeric effluent benchmarks were found; water quality provisions are narrative-only.
- 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
Coverage threshold
The project disturbs 1 acres, at or above the 1 acre threshold, so it needs permit coverage.
- 2
Permitting authority
Montana. The state runs its own programme under MTR100000.
- 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.
VerifiedMTR100000 General Permit, Part 3.2 (SWPPP Preparer and Administrator): "SWPPP Preparers and Administrators must obtain certification from a course approved by DEQ and maintain a valid certification by meeting the requirements in Parts 3.2.1, 3.2.2, and 3.2.3, as applicable to their role. Consistent with standard industry practice, a SWPPP Preparer or Administrator certification is valid no more than 3 years after date of certification."Source
What to do next
- 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. 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. 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. Read the requirements in full. SWPPP requirements in Montana
Screen a Montana site now
Runs in your browser. Nothing about the site is 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.