Montana's New Exempt Well Rules: 2026 Compliance Guide

If you’re planning to build a home or develop property in Montana, the way you think about your water source just changed. Following the 2025 Legislative session, several major updates—including House Bill 681—have officially reshaped how small groundwater wells (often called "exempt wells") are managed across the state.

Whether you are a homeowner, a developer, or a buyer, here is what you need to know to stay compliant and protect your property’s water future.

1. The Two-Stage Filing Process

The biggest change is the shift from a single filing to a two-stage process. Starting January 1, 2026, you can no longer simply drill a well and report it later.

• Step 1: Notice of Intent (NOI): Before you even start your project, you must file a "Notice of Intent to Appropriate Groundwater". This allows the DNRC to verify that your project actually qualifies for a permit exception before you spend money on infrastructure.
  
  

• Step 2: Notice of Completion (Form 602): Once the well is finished and the water is put to use, you must file a Notice of Completion to receive your official Groundwater Certificate.
  

Note for existing users: If you are already using water but never filed, you must still start with a Notice of Intent. The DNRC cannot process a Notice of Completion without an authorized NOI on file.

2. Updated Standards for "Exempt Wells"

To qualify for the permitting exception, your well must meet specific criteria:

• Limits: The well must divert 35 gallons per minute (GPM) or less and use 10 acre-feet or less per year.
  

• Bedroom-Based Math: For domestic use, the DNRC has moved away from a flat "one-acre-foot per house" rule. Water use is now calculated based on the number of bedrooms in the home, which aligns with DEQ standards.
  

• Subdivision Caps: Recent court rulings mean that different phases of a single subdivision are now treated as one unit. This means the entire subdivision shares a single 10 acre-foot limit, which usually supports about 18 to 22 homes.
  
  

3. Important Deadlines and Fees

Navigating the bureaucracy requires keeping an eye on the clock and your budget:

• Filing Fees: A Notice of Intent (NOI) costs $400. The Notice of Completion (Form 602) requires an additional $250.
  

• Approval Timelines: Once you submit a correct NOI, the DNRC has 10 business days to review and authorize or deny it.
  

• Project Window: An authorized NOI "locks in" current rules for your project for five years, with the possibility of extending it to ten.
  

Moving Forward: What Should You Do?

1. Verify Before You Buy: If you are looking at land in a subdivision, check if the 10 acre-foot limit has already been met. Some areas, like Riverwood or Bridger Shadows, have already seen well permits delayed or denied due to these caps.
   

2. File Early: Don't wait until you're ready to build. Filing your NOI early secures your place in the regulatory landscape.
   

3. Consult the Experts: The DNRC’s regional offices (located in hubs like Bozeman, Missoula, and Billings) are the best resource for technical facts and form assistance.