Before You Dig in Montana: Who to Call and What Permits You Need
Before you put a shovel in the ground for a new patio, fence, hot tub pad, or pool, call Montana 811 at least 2 business days ahead and check whether your project needs a permit. Both steps are quick, the 811 locate is free, and skipping them can mean a cut gas line, a lost weekend, or a stop-work order.
At Big Sky Outdoor Spaces we dig a lot of holes around Missoula, from pool excavations to post footings to trenches for gas and electrical runs. Here is the same pre-dig routine we follow on every job, written so homeowners can use it too.
Step 1: Call Montana 811 before any digging
Montana law requires anyone who digs, homeowners included, to notify utility owners through the one-call center before they start (MCA 69-4-503). Dial 811 from any phone (or 1-800-551-8344) and you will get a ticket number. The service is free (Montana 811).
What to know about the process:
Call at least 2 full business days ahead, not counting the day you call. Utility owners have 2 business days to locate and mark their lines. Weekends and holidays do not count, so a Friday call means Wednesday at the earliest, and for a weekend project Tuesday is the latest day to call (Montana One Call Center).
Plan to dig soon after. A locate request covers work you intend to start within 10 days and finish within 30 days. Marks are good for 30 days; if you have not dug by then, call again for a fresh locate.
Small jobs count too. Fence posts, mailbox posts, trees, deck footings, and trenching for low-voltage lighting all need a locate. A single post hole can hit a shallow gas service line.
The narrow exceptions. State law excludes homeowner gardening in established garden areas and homeowner landscaping without mechanized equipment, both less than 12 inches deep (MCA 69-4-501). If you are renting an auger, mini excavator, or trencher, you need a locate.
Tip: mark your planned dig area with white paint or white flags before the locators arrive. It tells them exactly where to focus and avoids a site that is marked everywhere except where you plan to work.
Step 2: Read the marks and find your private lines
Locators mark lines with paint and flags using the APWA uniform color code. Under Montana law a mark is "reasonably accurate" if the line sits within 18 inches of either side of it, so treat that strip as a hand-dig zone and expose the line carefully before using machinery nearby.
Color | What is buried there |
Red | Electric power |
Yellow | Gas, oil, steam, propane |
Orange | Phone, cable, internet, fiber, alarm lines |
Blue | Drinking water |
Green | Sewer and storm drain |
Purple | Reclaimed water, irrigation, slurry lines |
Pink | Temporary survey marks |
White | Your proposed dig area |
811 does not mark everything. Utilities mark only their own lines. The water company may not mark the line from the meter to your house, and the power company usually will not mark lines running to pool pumps and heaters, irrigation systems, or another building. Lines you or a past owner installed are private and will not show up, such as:
Power run to a detached garage, shop, or existing hot tub
Gas lines to a grill, fire pit, patio heater, or outdoor kitchen
Propane lines from a tank to the house
Sprinkler lines and low-voltage landscape lighting
Septic tanks, drain fields, and well lines on rural lots
If you have any of these, dig gently near them or hire a private utility locator before machine work starts.
Step 3: Check which permits your project needs
An 811 locate is not a permit. Most outdoor projects that involve digging also need a building, electrical, or site permit, and the rules depend on where you live. Inside Missoula city limits, the City of Missoula Building Division sets these common thresholds:
Project | Permit needed in the City of Missoula? |
Fences | Yes, a fence permit for all fences regardless of height; a building permit over 7 ft |
Decks | Yes, unless free-standing, 30 in or less above grade, 200 sq ft or less, no roof or arbor, and not serving the main exit door |
Retaining walls | Yes, over 4 ft from bottom of footing to top of wall, or any wall holding back a slope, driveway, or other load |
Swimming pools | Yes. The city FAQ does not list a size or depth cutoff, so call about small above-ground pools and hot tubs |
Sheds and small structures | Not under 200 sq ft (residential), but zoning setbacks and height limits still apply |
Work in the boulevard, sidewalk, or street | Yes, a right-of-way or excavation permit from City Engineering |
Other permits that often come up on outdoor projects:
Electrical. Hot tubs, swim spas, pool equipment, outdoor kitchens, and lighting circuits need an electrical permit. A homeowner may wire their own home and property under a homeowner permit; otherwise a licensed electrician pulls it. Inside the city it comes from the City of Missoula, in the rest of Missoula County from the County Building Division (406-258-3701), and in areas without a local program from the state Building Codes Bureau (406-841-2056).
Gas and plumbing. New gas lines to a grill, fire feature, or pool heater need a permit and inspection, usually pulled by the licensed plumber or gas fitter doing the work.
Floodplain and stream permits. Properties near the Clark Fork, Bitterroot, Rattlesnake Creek, or other streams may need a floodplain permit. Work in or near a stream or its bank needs a 310 permit, issued by the Missoula Conservation District (406-258-3430) in most of the county, or by Missoula County inside the old 1946 city limits.
County, HOA, and covenants. Outside city limits, building permits come from the Missoula County Building Division or your own county. Many subdivisions also have HOA rules on fences, pools, and structures.
Not sure? Call the City of Missoula Building Division at 406-552-6630 before you start. Their own FAQ notes that its list does not cover every type of work.
Your pre-dig checklist
Sketch the project and mark the dig area in white paint or flags
Call 811 at least 2 business days before digging
Confirm every utility has marked or cleared your site
Locate private lines: sprinklers, outbuilding power, gas to grills or fire pits, septic
Check city or county permit rules, plus HOA covenants
Apply for permits and wait for approval before breaking ground
Hand dig within 18 inches of any mark
Call 811 again if your work runs past 30 days
Let Big Sky Outdoor Spaces handle it
When you build with Big Sky Outdoor Spaces, we make the 811 call and walk you through the permits and inspections your project needs. We excavate pools, set hot tubs and swim spas, and build decks, patios, fences, retaining walls, and outdoor kitchens across the Missoula area, working with licensed electricians and plumbers for the trade work.
Planning a project for next season? Call us at 406-493-0570 or stop by the showroom at 2100 Stephens Ave, Missoula (Monday to Friday 10 to 6, weekends by appointment).
This post is general information, not legal advice. Permit rules change, so confirm requirements with your local building department before you start.
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