NR 116.09(1)(b)5.a. a. Assuming the dam is in place,

NR 116.09(1)(b)5.b. b. Assuming the dam is not in place, and

NR 116.09(1)(b)5.c. c. Assuming failure of the dam during the regional flood.

NR 116.09(1)(b)6. 6. For areas adjacent to levees, floodwalls and channel improvements, the floodway and floodfringe districts based on 2 conditions:

NR 116.09(1)(b)6.a. a. Assuming the levee, floodwall or channel improvement is not in place, and

NR 116.09(1)(b)6.b. b. Assuming the levee, floodwall or channel improvement is in place.

NR 116.09(1)(c) (c) If technical information is available to ascertain the magnitude of floods larger than the regional flood the floodplain limits of these large floods may be reflected on the official floodplain zoning maps and used for either public information purposes or for regulation.

NR 116.09(2) (2) If the regional flood profile has not been determined, maps based upon historical floods, flood prone area maps, flood hazard boundary maps, aerial photos or detailed soils maps may initially serve as a basis for floodplain delineation, provided that the associated text of the zoning ordinance provides for a procedure similar to ss. NR 116.20 (2) and 116.21 (3) to ascertain the effects of all development upon flood flows and the regional flood elevation.

NR 116.09 History History: Cr. Register, February, 1986, No. 362, eff. 3-1-86.

NR 116.10 NR 116.10 Conflicts between water surface profiles and floodplain zoning maps. Accepted engineering principles and techniques shall govern the transfer of profile elevation for use in delineation of the floodplain limits on the official floodplain zoning maps. If a conflict exists between the floodplain limits illustrated on the maps and the actual field conditions, the elevations from the water surface profile shall be the governing factor in locating the official floodplain limits.

NR 116.10 History History: Cr. Register, February, 1986, No. 362, eff. 3-1-86.

NR 116.11 NR 116.11 Criteria for establishing and rezoning floodplain districts.

NR 116.11(1) (1) Delineation of floodway, floodfringe and coastal floodplain districts. Except as provided in sub. (2), the following criteria shall apply to the delineation of floodway, floodfringe and coastal floodplain districts.

NR 116.11(1)(a) (a) Floodway district. The official floodway lines shown on floodplain zoning maps shall be the hydraulic floodway lines. These hydraulic floodway lines shall be determined by studies complying with the standards contained in s. NR 116.07.

NR 116.11(1)(b) (b) Floodfringe district. All areas within the floodplain landward of the official floodway lines shall be shown as a “floodfringe district.”

NR 116.11(1)(c) (c) Coastal floodplain district. All areas adjacent to Lake Superior or Lake Michigan within the regional floodplain shall be designated as a coastal floodplain district.

NR 116.11(2) (2) Redelineation or rezoning floodplain districts. In accordance with the criteria of sub. (3), the following redelineations or rezonings may occur:

NR 116.11(2)(a) (a) Redelineation or rezoning the floodway district to floodfringe district. Riverward delineations of the official floodway lines established in accordance with sub. (1) (a) are permissible provided the following criteria are satisfied:

NR 116.11(2)(a)1. 1. Any increase in regional flood height due to the delineation of the official floodway lines riverward from the hydraulic floodway lines shall be approved by the department prior to becoming effective. Increases may only be approved by the department if the provisions of sub. (3) are satisfied.

NR 116.11(2)(a)2. 2. The effects of delineating the official floodway lines riverward from the hydraulic floodway lines shall be calculated by comparing the regional flood profile determined from the hydraulic floodway lines to that profile determined by assuming that the area landward of the revised floodway lines is not available to convey flood flows. Calculations shall conform to the standards contained in s. NR 116.07.

NR 116.11(2)(b) (b) Redelineation or rezoning floodfringe district to floodway district. Landward modifications of hydraulic floodway lines to delineate official floodway lines may be permitted provided the following conditions are satisfied:

NR 116.11(2)(b)1. 1. The redelineation of the floodway lines is consistent with other municipal codes, ordinances, and ch. 30, Stats.; and

NR 116.11(2)(b)2. 2. The current hydraulic floodway lines, which reflect the water surface profile used for regulation, shall be kept on file by the municipality.

NR 116.11(2)(c) (c) Redelineation or rezoning floodway district to shallow depth flooding district. For areas subject to shallow depth flooding, the official floodway lines may be delineated riverward of the hydraulic floodway lines, provided all of the criteria in this paragraph are satisfied:

NR 116.11(2)(c)1. 1. The maximum depth of flooding during the regional flood in the shallow depth flooding district may not exceed one foot in depth nor 6 hours in duration. The duration shall be determined by a synthetic hydrograph developed for the watershed and routed through the area;

NR 116.11(2)(c)2. 2. The area is developed complete with existing streets and sewers and is subject to a land use plan, which includes provisions for drainage ways through the area with the capacity to convey that percentage of the regional flood which is flowing through the area under existing conditions;

NR 116.11(2)(c)3. 3. The municipality shall adopt standards outlined in s. NR 116.14 (1) pertaining to shallow depth flooding district;

NR 116.11(2)(c)4. 4. All areas within the hydraulic floodway landward of the official floodway lines shall be designated as “shallow depth flooding district”; and

NR 116.11(2)(c)5. 5. All areas within the floodplain landward of the hydraulic floodway lines shall be delineated as “floodfringe district”.