§ 151.12 FLOODWAY DISTRICT (FW).
   (A)   Permitted uses. The following uses, subject to the standards set forth in division (B) of this section, are permitted uses if otherwise allowed in the underlying zoning district or any applicable overlay district:
      (1)   General farming, pasture, grazing, farm fences, outdoor plant nurseries, horticulture, forestry, sod farming, and wild crop harvesting.
      (2)   Loading areas, parking areas, streets, trails, airport landing strips, railroads, bridges, culverts, utility transmission lines and pipelines.
      (3)   Open space uses, including but not limited to private and public golf courses, tennis courts, driving ranges, archery ranges, picnic grounds, boat launching ramps, swimming areas, parks, wildlife and nature preserves, game farms, fish hatcheries, shooting preserves, hunting and fishing areas, and single or multiple purpose recreational trails.
      (4)   Residential yards, lawns, gardens, parking areas, and play areas, provided these uses do not include associated accessory structures.
      (5)   Grading or land alterations associated with stabilization projects.
   (B)   Standards for floodway permitted uses. In addition to the applicable standards outlined in minimum development standards, all new development:
      (1)   The use must have a low flood damage potential.
      (2)   The use must not involve structures.
      (3)   The use must not obstruct flood flows, or increase velocities, stages, or flood damages, as certified by a registered professional engineer.
      (4)   Development that will change the course, current or cross section of protected wetlands or public waters is required to obtain a public waters work permit in accordance with M.S. § 103G.245 or a utility crossing license in accordance with M.S. § 84.415, from the Department of Natural Resources, or demonstrate that no permit is required, before applying for a local permit.
      (5)   Any facility that will be used by employees or the general public must be designed with a flood warning system that provides adequate time for evacuation if the area is inundated to a depth and velocity such that the depth (in feet) multiplied by the velocity (in feet per second) would exceed a product of four upon occurrence of the base flood.
   (C)   Conditional uses. The following uses may be allowed as conditional uses following the standards and procedures set forth in § 151.19.
      (1)   Structures accessory to primary uses listed under § 151.12(A)(1) through (3) above and primary uses listed in § 151.12(C)(2) through (6).
      (2)   Grading, extraction, fill and storage of soil, sand, gravel, and other materials for purposes other than stabilization projects.
      (3)   Marinas, boat rentals, permanent docks, piers, wharves, water control structures, and navigational facilities.
      (4)   Storage yards for equipment, machinery, or materials.
      (5)   Fences that have the potential to obstruct flood flows.
      (6)   Levees or dikes intended to protect agricultural crops for a frequency flood event equal to or less than the ten-year frequency flood event.
   (D)   Standards for floodway conditional uses. In addition to the applicable standards outlined in § 151.11:
      (1)   Fill; storage of materials and equipment.
         (a)   Fill, dredge spoil, and other similar materials deposited or stored in the floodplain must be protected from erosion by the use of mulches or similar materials, with permanent vegetative cover established as soon as possible. Permanent sand and gravel operations and similar uses must be covered by a long-term site development plan.
         (b)   Temporary placement of fill, other materials, or equipment that would cause an increase to the stage of the base flood may only be allowed if the city has approved a plan that assures removal of the materials from the floodway based upon the flood warning time available.
      (2)   Accessory structures. Accessory structures, as identified under § 151.12, may be permitted, provided that:
         (a)   Structures are not intended for human habitation;
         (b)   Structures will have a low flood damage potential;
         (c)   Structures will be constructed and placed so as to offer a minimal obstruction to the flow of flood waters;
         (d)   Structures must be elevated on fill or structurally dry floodproofed and watertight to the regulatory flood protection elevation. Certifications consistent with § 151.17(B)(6) shall be required.
         (e)   As an alternative, an accessory structure may be floodproofed in a way to accommodate internal flooding. To allow for the equalization of hydrostatic pressure, there shall be a minimum of two openings on at least two sides of the structure and the bottom of all openings shall be no higher than one foot above grade. The openings shall have a minimum net area of not less than one square inch for every square foot of enclosed area subject to flooding, have a net area of not less than one square inch for every square foot of enclosed area subject to flooding, and shall allow automatic entry and exit of floodwaters without human intervention. A floodproofing certification consistent with § 151.17(B)(6) shall be required.
      (3)   A levee, dike, or floodwall constructed in the floodway must not cause an increase to the base flood. The technical analysis must assume equal conveyance or storage loss on both sides of a stream.
(Ord. 161, passed 3-5-2012; Ord. 202, passed 9-20-2021)