Chapter NR 116

NR 116.08(3)(b) (b) Developed areas downstream of compliant dams shall be zoned and regulated as follows:

NR 116.08(3)(b)1. 1. For high hazard dams, assuming that the dam is nonexistent during the regional flood.

NR 116.08(3)(b)2. 2. For significant or low hazard dams, assuming the dam fails during the regional flood.

NR 116.08(3)(c) (c) Undeveloped areas downstream of a compliant dam shall be zoned and regulated assuming that the dam fails during the regional flood.

NR 116.08(4) (4) Noncompliant dams.

NR 116.08(4)(a) (a) If an existing dam does not meet the standards in sub. (3) (a), the dam is considered noncompliant.

NR 116.08(4)(b) (b) Both developed and undeveloped areas downstream of a noncompliant dam shall be zoned and regulated assuming that dam failure occurs during the regional flood.

NR 116.08(4)(c) (c) The regional flood profile of the area downstream of the dam shall be calculated in accordance with s. NR 333.05 (2) (b).

NR 116.08(5) (5) Construction of new dams.

NR 116.08(5)(a) (a) Dams constructed after August 1, 2001, shall be considered compliant if the requirements in sub. (3) (a) are met.

NR 116.08(5)(b) (b) Developed areas downstream of the construction of a new dam shall be zoned and regulated as if the dam does not exist until construction is 100% complete and all the conditions of sub. (3) (a) are met.

NR 116.08 History History: Cr. Register, February, 1986, No. 362, eff. 3-1-86; CR 00-136: am. (1), (2), (3) (a) 1. to 5., (b), (c), (4) (a) and (b) and (5) (a), Register July 2001, No. 547 eff. 8-1-01.

NR 116.09 NR 116.09 Data required to be shown on floodplain zoning maps. Municipalities shall delineate the entire floodplain on their floodplain zoning maps.

NR 116.09(1) (1) If the regional flood profile has been determined, the profile shall be used to develop the floodplain zoning maps which the municipality shall use as the basis for floodplain zoning.

NR 116.09(1)(a) (a) The maps shall show the following:

NR 116.09(1)(a)1. 1. The floodway district;

NR 116.09(1)(a)2. 2. The floodfringe district;

NR 116.09(1)(a)3. 3. The regional flood elevation consistent with the regional flood profile shall be clearly lettered at identifiable positions on the official floodplain zoning maps. If for any reason that elevation is not shown on the maps, the profile shall be attached to and made a part of the maps; and

NR 116.09(1)(a)4. 4. Source and date of study.

NR 116.09(1)(b) (b) In addition to the information in par. (a), the floodplain zoning maps shall include the following information, where applicable:

NR 116.09(1)(b)1. 1. The shallow depth flooding district.

NR 116.09(1)(b)2. 2. The flood storage district.

NR 116.09(1)(b)3. 3. The coastal floodplain district.

NR 116.09(1)(b)4. 4. Floodplain islands.

NR 116.09(1)(b)5. 5. For developed and undeveloped areas downstream of dams, the floodway and floodfringe districts based on 3 conditions:

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”.

NR 116.11(2)(d) (d) Redelineation or rezoning floodfringe district to flood storage district. A “flood storage district” may be established for the area landward of the floodway in lieu of the floodfringe designation where floodplain storage will decrease the calculation of discharge and therefore the regional flood elevation, provided the following criteria are met:

NR 116.11(2)(d)1. 1. The department shall approve the methodology used to analyze floodplain storage to determine revised regional flood elevations.

NR 116.11(2)(d)2. 2. The municipality shall adopt standards outlined in s. NR 116.14 (2) pertaining to the flood storage district.

NR 116.11(2)(e) (e) Rezoning flood storage district to floodfringe district. Any proposal to rezone flood storage district to floodfringe district shall comply with the following conditions:

NR 116.11(2)(e)1. 1. Any increase in regional flood height shall be approved by the department prior to becoming effective. Increases in the regional flood elevation may only be approved by the department if the provisions in sub. (3) are satisfied; and

NR 116.11(2)(e)2. 2. The effect of rezoning the flood storage district to the floodfringe district shall be calculated by comparing the regional flood profile used as the basis for zoning to the regional flood profile determined by assuming that the area to be rezoned is not available to store floodwater.

NR 116.11(2)(f) (f) Rezoning the shallow depth flooding district to floodfringe district. Any proposal to rezone the shallow depth flooding district to floodfringe district shall comply with the following conditions:

NR 116.11(2)(f)1. 1. Any increase in regional flood height shall be approved by the department prior to the rezoning becoming effective. Increases in the regional flood elevation may only be approved by the department if the provisions in sub. (3) are satisfied;

NR 116.11(2)(f)2. 2. The entire shallow depth flooding district shall be rezoned to floodfringe district; and

NR 116.11(2)(f)3. 3. The effect of rezoning the shallow depth flooding district to the floodfringe district shall be calculated by comparing the regional flood profile determined by the hydraulic floodway lines to the regional flood profile determined by assuming that the entire shallow depth flooding district is not available to convey floodflows. Calculations shall conform to the standards contained in s. NR 116.07.

NR 116.11(3) (3) Criteria for redelineation or rezoning floodplain districts.

NR 116.11(3)(a) (a) Initial determinations. Prior to redelineation or rezoning any floodplain district a municipality shall:

NR 116.11(3)(a)1. 1. Assure that the applicable provisions of sub. (2) are met;

NR 116.11(3)(a)2. 2. Require adequate technical data from the applicant or the municipality and submit such data to the department for review and concurrence in the effect of the proposed amendment on the height of the regional flood;

NR 116.11(3)(a)3. 3. Assure that the proposed amendments meet the purpose of s. NR 116.01;

NR 116.11(3)(a)4. 4. Assure that the appropriate legal arrangements have been made with all property owners affected by the increased flood elevations; and

NR 116.11(3)(a)5. 5. Notify all affected municipalities of increased regional flood elevations.

NR 116.11(3)(b) (b) Amendment process. Upon completion of the steps in par. (a), the municipality and any affected municipality shall meet all legal requirements for amending its water surface profiles, floodplain zoning maps and zoning ordinances as established in s. NR 116.21 (6).

NR 116.11(3)(c) (c) Submission to the department for approval. If the municipality amends its official floodplain map, it shall also amend its water surface profiles and floodplain zoning ordinance and submit these amendments to the department for approval pursuant to s. NR 116.21 (6). Prior to department approval, all municipalities affected by the increased regional flood elevation shall amend their water surface profiles, floodplain zoning maps and zoning ordinances to reflect the increased regional flood elevations.

NR 116.11(4) (4) Exception to criteria for redelineating or rezoning floodplain districts. If, as a result of improved data generated by a revised study approved by the department, and not as a result of changes due to encroachments in the floodplain, the hydraulic floodway line is revised landward of the official floodway lines, the municipality may continue to regulate on the basis of the official floodway lines provided the municipality meets all of the requirements of sub. (3), except the requirement of sub. (3) (a) 4.

NR 116.11 History History: Cr. Register, February, 1986, No. 362, eff. 3-1-86.

NR 116.12 NR 116.12 Development standards in floodway areas.

NR 116.12(1) (1) Prohibited uses. Municipalities shall prohibit the following uses in floodway areas:

NR 116.12(1)(a) (a) Except as provided in sub. (2), any development which will cause an obstruction to flood flows or an increase in regional flood discharge or will adversely affect the existing drainage courses or facilities.

NR 116.12(1)(b) (b) A structure is always prohibited in, on or over floodway areas if the structure is:

NR 116.12(1)(b)1. 1. Designed for human habitation;

NR 116.12(1)(b)2. 2. Associated with high flood damage potential; or

NR 116.12(1)(b)3. 3. Not associated with permanent open space uses.

NR 116.12(1)(c) (c) Any storage of materials that are buoyant, flammable, explosive or injurious to human, animal, plant, fish or other aquatic life.

NR 116.12(1)(d) (d) Any use which is not in harmony with, or which may be detrimental to, the uses permitted in the adjoining districts.

NR 116.12(1)(e) (e) Any sewage system, whether public or private, except portable latrines that are removed during flooding, or systems associated with recreational areas that meet the applicable provisions of local ordinances and ch. SPS 383.

NR 116.12(1)(f) (f) Any well, whether public or private, which is used to obtain water for ultimate human consumption, except systems associated with recreational areas that meet the applicable provisions of municipal zoning ordinances and chs. NR 811 and 812.

NR 116.12(1)(g) (g) Any solid or hazardous waste disposal facility.

NR 116.12(1)(h) (h) Any wastewater treatment pond or facility except as permitted in s. NR 110.15 (3) (b).

NR 116.12(1)(i) (i) Any sanitary sewer or water line except those used to service existing development or proposed development located outside of the floodway and which comply with the requirement for the floodplain area on which it is located.