The following artificial obstructions may be permitted in the floodway subject to the issuance of a permit by the floodplain administrator:

A. Excavation of material from pits and pools; provided, that:

1. A buffer strip of undisturbed land is left between the edge of the channel and the edge of the excavation. This buffer strip must be of sufficient width to prevent flood flows from channeling into the excavation,

2. The excavation meets all applicable laws and regulations of other local and state agencies, and

3. Excavated material is disposed of or stockpiled outside the floodway;

B. Railroad, highway, and street stream crossings, provided the crossings are designed to offer minimal obstruction to flood flow. Stream crossings shall not increase the elevation of the one-hundred-year flood more than one-half foot nor cause a significant increase in flood velocities;

C. Limited filling for highway, street and railroad embankments not associated with stream crossings; provided, that:

1. Reasonable alternate transportation routes outside the designated floodway are not available, and

2. Such floodway encroachment is located as far from the stream channel as possible and shall not result in a cumulative increase in base flood elevations, after allowable encroachments into the floodway fringe, exceeding one-half foot;

D. Buried or suspended utility transmission lines; provided, that:

1. Suspended utility transmission lines are designed so the lowest point of the suspended line is at least six feet higher than the base flood elevation,

2. Towers and other appurtenant structures are designed and placed to withstand and minimally obstruct flood flows, and

3. Utility transmission lines carrying toxic or flammable materials are buried to a depth of at least twice the calculated maximum depth of scour for a one-hundred-year flood. The maximum depth of scour shall be determined by hydraulic engineering methods acceptable to the floodplain administrator;

E. Storage of materials and equipment; provided, that:

1. The material or equipment is not subject to major damage by flooding and is properly anchored to prevent floatation or downstream movement, or

2. The material or equipment is readily movable within the limited time available after flood warning. Storage of flammable, toxic, hazardous, or explosive materials shall not be permitted;

F. Domestic water supply wells; provided, that:

1. They are driven or drilled wells located on ground higher than the surrounding ground to assure positive drainage from the well,

2. Well casings are watertight to a distance of at least twenty-five feet below the ground surface,

3. Water supply and electrical lines have a watertight seal where the lines enter the casing,

4. All pumps, electrical lines, and equipment are either submersible or adequately floodproofed, and

5. Check valves are installed on main water lines at wells and at all building entry locations;

G. Buried and sealed vaults for sewage disposal in recreational areas, provided they meet applicable laws and standards administered by the Montana Department of Health and Environmental Sciences;

H. Public or private campgrounds; provided that:

1. Access roads require only limited fill and do not obstruct or divert floodwaters, and

2. Recreational vehicles and travel trailers are licensed and ready for highway use. They are ready for highway use if on wheels or jacking system with wheels intact, are attached to the site with only quick disconnect type utilities and securing devices, and have no permanently attached additions;

I. Structures accessory to the uses permitted in this section such as boat docks, marinas, sheds, picnic shelters, tables, and toilets; provided, that:

1. The structures are not intended for human habitation,

2. The structures will have a low flood damage potential,

3. The structures will, insofar as possible, be located on ground higher than the surrounding ground and as far from the channel as possible,

4. The floodproofing standards of Article VII are met, and

5. The structures will be constructed and placed so as to offer minimal obstruction to flood flows and are anchored to prevent floatation;

J. Substantial improvements to any structure provided that the provisions of Section 15.28.330(C), (D) and (E) of this chapter are met. In the floodway the structure must be floodproofed or elevated on a permanent foundation rather than on fill;

K. All other artificial obstructions, substantial improvements, or nonconforming uses not specifically listed or prohibited by these regulations. (Ord. 576 § 6(B)(2), 1994)