NR 116.08(1)(1) General. Adequately designed, constructed and maintained dams provide reduced damages and relief from flooding for developed areas. Areas downstream of dams shall be zoned and regulated by municipalities with floodplain zoning ordinances in compliance with the standards in this section, to reduce potential loss of life and property located downstream of the dams. Except as provided in sub. (2), areas downstream of all dams shall be delineated on floodplain maps in accordance with s. NR 116.09 (1) (b) 5. Flood studies and related mapping, completed and adopted prior to August 1, 2001, which calculated flood flow attenuation based on the existence of the dam structures within the contributing basin, may continue to use the dam in-place, no failure, profile. NR 116.08(2)(2) Exemptions. All dams having a structural height of 6 feet or less, or a storage capacity of 15 acre feet or less, and all dams having a structural height of more than 6 feet but less than 25 feet with a storage capacity of less than 50 acre feet are exempt from the requirements of this section unless the department determines pursuant to s. 31.19, Stats., that the dam is likely to endanger life, health or property. NR 116.08(3)(a)(a) A dam is considered compliant if all the following requirements are met: NR 116.08(3)(a)3.3. The dam has been certified by a professional engineer, registered in Wisconsin, to meet the requirements of subds. 1. and 2. NR 116.08(3)(a)4.4. Written assurance of the dam owner’s ability to operate and maintain the dam in good condition is obtained from the dam owner. NR 116.08(3)(a)5.5. An emergency action plan to minimize loss of human life has been developed for the area downstream of the dam based on the assumption that the dam fails during the regional flood. 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)(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(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 HistoryHistory: 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 116.09NR 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)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)(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)5.5. For developed and undeveloped areas downstream of dams, the floodway and floodfringe districts based on 3 conditions: 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)(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 HistoryHistory: Cr. Register, February, 1986, No. 362, eff. 3-1-86. NR 116.10NR 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 HistoryHistory: Cr. Register, February, 1986, No. 362, eff. 3-1-86. NR 116.11NR 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)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)(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)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)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 HistoryHistory: Cr. Register, February, 1986, No. 362, eff. 3-1-86. NR 116.12NR 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:
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Chs. NR 100-199; Environmental Protection – General
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