Excavation permits and rules in Montana

Anyone digging in Montana has to notify Montana 811 before work starts. Call 811 at least 3 business days before digging.^1-2

Text of the law

The notice period under Mont. Code Ann. 69-4-501 to 69-4-530: At least three business days before you begin excavation (Montana 811); statute requires owners to locate and mark within 2 business days of notification.^1-2

Montana licenses contractors through the Montana Department of Labor and Industry, Construction Contractor License (CCL) Program. Who needs a license: Construction contractors with employees, and corporations and manager-managed LLCs regardless of employee count (effective January 1, 2026). The statutory definition of construction contractor expressly includes excavation; the license replaced the former contractor registration under 2025 House Bill 239.^3-4

A stormwater permit is needed at 1 acre, or less than 1 acre if part of a larger common plan of development or sale whose total area is 1 acre or more. Coverage is under the General Permit for Storm Water Discharges Associated with Construction Activity MTR100000 (effective January 1, 2023, expires December 31, 2027).⁵

Footings in Montana go below the frost line, which the state building code sets at 36 to 48 inches.⁶