Mont. Code Ann. § 76-5-1105

Whenever any city, town, or county has begun a water conservation or flood control system, or both, under this part, the council, board, or other governing body shall have the power to divide the work into parts, sections, or districts; to omit parts of said work; and to contract for any part or section separately and proceed therewith the same as if the entire work or improvements were contracted for, done, or made.