As used in this sub-chapter and in Title 75, chapter 7, part 1, MCA, the following definitions apply:

(1) "Act" means the Natural Streambed and Land Preservation Act.

(2) "Bed" means the channel occupied by a stream.

(3) "Channel" means the area of a stream measured from mean high water mark to mean high water mark.

(4) "Emergency" means an unforseen event or combination of circumstances that call for immediate action to safeguard life, including human or animal, or property, including growing crops, without giving time for the deliberate exercise of judgment or discretion under the act.

(5) "Immediate banks" means the area above the mean high water mark and directly adjacent to a stream which when disturbed will physically alter or modify the state of a stream in contravention of 75-7-102, MCA.

(6) "Mean high water mark" means the line that water impresses on the land for sufficient periods to cause physical characteristics that distinguish the area below the line from above it. Characteristics of the area below the line include, when appropriate, deprivation of the soil of substantially all terrestrial vegetation and destruction of its agricultural value.

(7) "Natural perennial flowing stream" means a stream which in the absence of diversion, impoundment, appropriation, or extreme drought flows continuously at all seasons of the year and during dry as well as wet years.

(8) "Plan of operation" means an annual plan for a project of recurring nature that, if approved by the supervisors, authorizes a specific activity for a period not to exceed 10 years.