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MontanaHB 18069th Legislature, Regular Session (2025)House

Revise sanitation in subdivision laws related to mixing zones

Sponsored By: Courtenay Sprunger (Republican)

Signed by Governor

PlanningWaterCountiesEnvironmental ProtectionLocal Government

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Bill Overview

Analyzed Economic Effects

2 provisions identified: 1 benefits, 0 costs, 1 mixed.

Stricter septic and well setback rules

The law tightens where new septic drainfields and wells can go near property lines. For parcels created after March 30, 2011, local health boards must deny a septic system if its mixing zone would cross onto a neighbor’s land, unless a narrow state-law exception allows it. Where local boards permit wells, they must also deny drilling if the well’s isolation zone would encroach on a neighbor’s land, unless that neighbor authorizes it. A well isolation zone is generally a 100-foot radius around a well, unless DEQ approves a site-specific distance. A “proposed drainfield mixing zone” means one submitted after March 30, 2011 for a parcel created after that date. Mixing zones approved before March 30, 2011, and those approved under Title 50 before October 1, 2025, keep their prior status.

Uniform septic variance rules and appeals

Local health boards must use the same standards as the state Department of Environmental Quality when deciding sewage variances. If the board denies or conditions your variance, you can appeal to DEQ. This creates a single, clear process across counties.

Sponsors & Cosponsors

Sponsor

  • Courtenay Sprunger

    Republican • House

Cosponsors

  • Forrest Mandeville

    Republican • Senate

Roll Call Votes

All Roll Calls

Yes: 297 • No: 0

Senate vote • 4/9/2025

Do Concur

Yes: 49 • No: 0

Senate vote • 4/8/2025

Do Concur

Yes: 49 • No: 0

House vote • 1/31/2025

Do Pass

Yes: 99 • No: 0

House vote • 1/30/2025

Do Pass

Yes: 100 • No: 0

Actions Timeline

  1. Chapter Number Assigned

    5/5/2025House

  2. Signed by Governor

    5/1/2025House

  3. Transmitted to Governor

    4/22/2025House

  4. Signed by President

    4/22/2025Senate

  5. Signed by Speaker

    4/18/2025House

  6. Returned from Enrolling

    4/10/2025House

  7. Sent to Enrolling

    4/9/2025House

  8. 3rd Reading

    4/9/2025Senate

  9. 2nd Reading

    4/8/2025Senate

  10. Committee Report

    3/24/2025Senate

  11. Committee Executive Action

    3/21/2025Senate

  12. Hearing

    3/5/2025Senate

  13. Referred to Committee

    2/18/2025Senate

  14. 1st Reading

    2/3/2025Senate

  15. Transmitted to Senate

    1/31/2025House

  16. 3rd Reading

    1/31/2025House

  17. 2nd Reading

    1/30/2025House

  18. Committee Report

    1/24/2025House

  19. Committee Executive Action

    1/23/2025House

  20. Committee Executive Action

    1/23/2025House

  21. Hearing

    1/14/2025House

  22. 1st Reading

    1/13/2025House

  23. Referred to Committee

    1/13/2025House

  24. Introduced

    1/13/2025House

Bill Text

  • Enrolled

    4/15/2025

    PDF

  • As Amended (Version 2)

    1/24/2025

    PDF

  • Introduced

    1/13/2025

    PDF

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