Montana Title 76. Land Resources and Use § 76-5-404. Artificial obstructions and nonconforming uses

(3)(a) Parts 1 through 4 of this chapter do not affect any existing artificial obstruction or nonconforming use established in the designated flood plain or designated floodway before the land use regulations adopted by the political subdivision are effective or before the department has enforced a designated flood plain or a designated floodway under 76-5-301(1) and (2).

(b) However, a person may not make nor may an owner allow alterations of an artificial obstruction or nonconforming use within a designated flood plain or a designated floodway whether the obstruction proposed for alteration was located in the flood plain or floodway before or after July 1, 1971, except upon express written approval of the department or the responsible political subdivision. Maintenance of an obstruction is not an alteration.