---
type: "Bill"
title: "Revise laws related to air quality standards"
description: "Revise laws related to air quality standards"
jurisdiction: "us/states/mt"
legislature: "Montana Legislature"
session: "2025"
identifier: "HB 291"
citation: "Montana HB 291 (2025)"
classification: ["bill"]
subjects: ["Environmental Protection", "Federal Government", "Rule Making"]
status: "enacted"
primary_sponsors: ["Greg Oblander"]
version_count: 30
action_count: 38
vote_count: 7
first_action: "2024-12-17T17:29:23+00:00"
last_action: "2025-05-05T13:59:46+00:00"
source: "openstates"
source_identifier: "ocd-bill/6131e6d1-957f-4939-8285-55c4dca981f4"
source_url: "https://bills.legmt.gov/#/laws/bill/2/LC2990?open_tab=sum"
source_hash: "9536c876eb6bf6179489c6abecbef9a2dbdbdd55c4de039dc55c037171a8c078"
vintage: "2026-07-01"
source_snapshot: "https://data.openstates.org/daily/2026-07-01/public.pgdump"
retrieved_at: "2026-07-06"
confidence: "reported"
tags: ["legislation", "bill", "us-mt"]
---

# Montana HB 291 (2025) — Revise laws related to air quality standards

## Version chain

The bill's text revisions, in order — the diff chain from filing to enrollment.

1. **HB0291.001.002_Amendments-in-Context_final-condensed.pdf** (committee substitute) — [source](https://api.legmt.gov/docs/v1/documents/getContent?documentId=281306)
2. **HB0291.001.002_Amendments-in-Context_final-full.pdf** (committee substitute) — [source](https://api.legmt.gov/docs/v1/documents/getContent?documentId=281305)
3. **HB0291_1(1).pdf** (committee substitute) — [source](https://api.legmt.gov/docs/v1/documents/getContent?documentId=273963)
4. **HB0291_1(2).pdf** (committee substitute) — [source](https://api.legmt.gov/docs/v1/documents/getContent?documentId=275499)
5. **HB0291_1(3).pdf** (committee substitute) — [source](https://api.legmt.gov/docs/v1/documents/getContent?documentId=276545)
6. **HB0291_1(4).pdf** (committee substitute) — [source](https://api.legmt.gov/docs/v1/documents/getContent?documentId=281947)
7. **HB0291_1(5).pdf** (committee substitute) — [source](https://api.legmt.gov/docs/v1/documents/getContent?documentId=281948)
8. **HB0291_1(6).pdf** (committee substitute) — [source](https://api.legmt.gov/docs/v1/documents/getContent?documentId=281949)
9. **HB0291_1(7).pdf** (committee substitute) — [source](https://api.legmt.gov/docs/v1/documents/getContent?documentId=281950)
10. **HB0291_1.pdf** (committee substitute) — [source](https://api.legmt.gov/docs/v1/documents/getContent?documentId=273680)
11. **HB0291_2(1).pdf** (committee substitute) — [source](https://api.legmt.gov/docs/v1/documents/getContent?documentId=281952)
12. **HB0291_2(10).pdf** (committee substitute) — [source](https://api.legmt.gov/docs/v1/documents/getContent?documentId=300659)
13. **HB0291_2(11).pdf** (committee substitute) — [source](https://api.legmt.gov/docs/v1/documents/getContent?documentId=305149)
14. **HB0291_2(12).pdf** (committee substitute) — [source](https://api.legmt.gov/docs/v1/documents/getContent?documentId=305151)
15. **HB0291_2(2).pdf** (committee substitute) — [source](https://api.legmt.gov/docs/v1/documents/getContent?documentId=281956)
16. **HB0291_2(3).pdf** (committee substitute) — [source](https://api.legmt.gov/docs/v1/documents/getContent?documentId=281957)
17. **HB0291_2(4).pdf** (committee substitute) — [source](https://api.legmt.gov/docs/v1/documents/getContent?documentId=281961)
18. **HB0291_2(5).pdf** (committee substitute) — [source](https://api.legmt.gov/docs/v1/documents/getContent?documentId=282245)
19. **HB0291_2(6).pdf** (committee substitute) — [source](https://api.legmt.gov/docs/v1/documents/getContent?documentId=282246)
20. **HB0291_2(7).pdf** (committee substitute) — [source](https://api.legmt.gov/docs/v1/documents/getContent?documentId=282247)
21. **HB0291_2(8).pdf** (committee substitute) — [source](https://api.legmt.gov/docs/v1/documents/getContent?documentId=282260)
22. **HB0291_2(9).pdf** (committee substitute) — [source](https://api.legmt.gov/docs/v1/documents/getContent?documentId=283827)
23. **HB0291_2.pdf** (committee substitute) — [source](https://api.legmt.gov/docs/v1/documents/getContent?documentId=281951)
24. **HB0291_X(1).pdf** (committee substitute) — [source](https://api.legmt.gov/docs/v1/documents/getContent?documentId=316692)
25. **HB0291_X(2).pdf** (committee substitute) — [source](https://api.legmt.gov/docs/v1/documents/getContent?documentId=320274)
26. **HB0291_X(3).pdf** (committee substitute) — [source](https://api.legmt.gov/docs/v1/documents/getContent?documentId=324622)
27. **HB0291_X(4).pdf** (committee substitute) — [source](https://api.legmt.gov/docs/v1/documents/getContent?documentId=326796)
28. **HB0291_X(5).pdf** (committee substitute) — [source](https://api.legmt.gov/docs/v1/documents/getContent?documentId=327778)
29. **HB0291_X.pdf** (committee substitute) — [source](https://api.legmt.gov/docs/v1/documents/getContent?documentId=310751)
30. **LC2990.pdf** (committee substitute) — [source](https://api.legmt.gov/docs/v1/documents/getContent?documentId=272636)

## Votes

- Do Concur — **30–19** (pass) · upper
- Do Pass — **61–38** (pass) · lower
- Do Pass As Amended — **60–40** (pass) · lower
- Do Concur — **32–18** (pass) · upper
- do_pass — **8–6** (pass) · lower
- be_concurred_in — **6–5** (pass) · upper
- AMD-HB0291.001.002 Oblander DO PASS — **99–1** (pass) · lower

## Sponsors

- Greg Oblander — primary (person)

## Timeline

The legislative action history — every referral, reading, and vote.

- **2024-12-17T17:29:23+00:00** (LC) Drafter Assigned
- **2024-12-20T20:39:46+00:00** (LC) Draft Taken Off Hold
- **2025-01-18T20:00:21+00:00** (LC) Draft in Legal Review
- **2025-01-20T14:41:33+00:00** (LC) Draft in Edit
- **2025-01-20T16:00:06+00:00** (LC) Draft in Input/Proofing
- **2025-01-20T17:49:15+00:00** (LC) Draft in Final Drafter Review
- **2025-01-20T20:15:40+00:00** (LC) Draft in Assembly
- **2025-01-20T20:27:55+00:00** (LC) Draft Ready for Delivery
- **2025-01-21T23:03:35+00:00** (LC) Draft Delivered to Requester
- **2025-01-22T22:49:05+00:00** (H) Introduced
- **2025-01-23T18:53:22+00:00** (H) Referred to Committee - (H) Natural Resources `referral-committee`
- **2025-01-23T20:08:19+00:00** (H) First Reading `reading-1`
- **2025-01-30T00:31:51+00:00** (H) Hearing - (H) Natural Resources
- **2025-02-07T23:17:34+00:00** (H) Committee Executive Action--Bill Passed - (H) Natural Resources `committee-passage`
- **2025-02-10T20:24:00+00:00** (H) Committee Report--Bill Passed - (H) Natural Resources `committee-passage`
- **2025-02-12T20:00:00+00:00** (H) Scheduled for 2nd Reading `reading-2`
- **2025-02-12T20:40:00+00:00** (H) 2nd Reading Motion to Amend Carried `reading-2`
- **2025-02-12T20:45:00+00:00** (H) 2nd Reading Passed as Amended `reading-2, reading-2`
- **2025-02-18T20:00:00+00:00** (H) Scheduled for 3rd Reading `reading-3`
- **2025-02-18T21:21:00+00:00** (H) 3rd Reading Passed `passage, reading-3`
- **2025-02-18T21:50:00+00:00** (H) Transmitted to Senate
- **2025-02-19T20:32:58+00:00** (S) First Reading `reading-1`
- **2025-03-01T22:13:16+00:00** (S) Referred to Committee - (S) Natural Resources `referral-committee`
- **2025-03-21T16:44:59+00:00** (S) Hearing - (S) Natural Resources
- **2025-03-28T21:44:24+00:00** (S) Committee Executive Action--Bill Concurred - (S) Natural Resources
- **2025-03-31T19:19:00+00:00** (S) Committee Report--Bill Concurred - (S) Natural Resources
- **2025-04-02T20:36:28+00:00** (S) 2nd Reading Pass Consideration `reading-2`
- **2025-04-03T23:00:00+00:00** (S) Scheduled for 2nd Reading `reading-2`
- **2025-04-04T00:50:00+00:00** (S) 2nd Reading Concurred `reading-2, reading-2`
- **2025-04-04T19:00:00+00:00** (S) Scheduled for 3rd Reading `reading-3`
- **2025-04-04T19:41:00+00:00** (S) 3rd Reading Concurred `passage, reading-3`
- **2025-04-04T19:42:02+00:00** (H) Sent to Enrolling
- **2025-04-05T13:03:41+00:00** (H) Returned from Enrolling
- **2025-04-18T19:00:46+00:00** (H) Signed by Speaker `passage`
- **2025-04-22T00:00:24+00:00** (S) Signed by President `passage`
- **2025-04-22T18:10:24+00:00** (H) Transmitted to Governor `executive-receipt`
- **2025-05-01T21:14:29+00:00** (H) Signed by Governor `executive-signature`
- **2025-05-05T13:59:46+00:00** Chapter Number Assigned `became-law`

## Source

OpenStates / OpenCivicData bulk snapshot [2026-07-01](https://data.openstates.org/daily/2026-07-01/public.pgdump); origin `ocd-bill/6131e6d1-957f-4939-8285-55c4dca981f4`. Confidence: reported (aggregated from official Montana legislature records).