Chapter NR 116

NR 116.07(4)(j)8.g. g. Channel roughness values.

NR 116.07(4)(j)8.h. h. Any other data required by the department.

NR 116.07(4)(k) (k) Wave action on the Great Lakes. Standards used to determine the regional flood elevation for all municipalities adjacent to the Great Lakes shall be those specified in the publication, “Guidelines and Specifications for Study Contractors, Federal Emergency Management Agency, September 1982, appendix 1B, Wave Runup Analysis”.

NR 116.07(5) (5) Document availability. The materials listed in this subsection are incorporated by reference in the corresponding subsections noted. The document referred to in sub. (3) (a) 1. may be purchased from the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402 (mention title and stock number 052-045-00031-2). The document referred to in sub. (3) (a) 2. is available for inspection at the Geological Survey — Water Resource Division, U.S. Department of the Interior, 1815 University Avenue, Madison, Wisconsin 53706. The document referred to in sub. (3) (a) 5. is available for inspection at the Soil Conservation Service, U.S. Department of Agriculture, 4601 Hammersley Road, Madison, Wisconsin 53711; it may be purchased from the National Technical Information Service, U.S. Department of Commerce, 5285 Port Royal Road, Springfield, Virginia 22151 (mention title and appropriate accession number: TR55 = PB 244531/AS). The document described in sub. (4) (c) and (d) is available for inspection at the United States Army Corps’ Hydrologic Engineering Center, 609 2nd Street, Davis, California 95616. The document referred to in sub. (4) (k) is available for inspection at the Federal Emergency Management Agency Region V Office, 300 South Wacker Drive, Chicago, Illinois 60606 (mention title, date and appropriate appendix number).

NR 116.07(6) (6) Inspection of documents. Copies of the documents referred to in sub. (5) are also available for inspection in the following offices:

NR 116.07(6)(a) (a) The department of natural resources, 101 South Webster Street, Madison, Wisconsin;

NR 116.07(6)(b) (b) The office of the secretary of state, 30 W. Mifflin Street, Madison, Wisconsin;

NR 116.07(6)(c) (c) The legislative reference bureau, One E. Main Street, Madison, Wisconsin.

NR 116.07 History History: Cr. Register, February, 1986, No. 362, eff. 3-1-86; corrections made under s. 13.93 (2m) (b) 6., Stats., Register, September, 1995, No. 477; correction in (6) (c) made under s. 13.92 (4) (b) 6., Stats., Register March 2011 No. 663.

NR 116.08 NR 116.08 Uses downstream of dams.

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) (3) Compliant dams.

NR 116.08(3)(a) (a) A dam is considered compliant if all the following requirements are met:

NR 116.08(3)(a)1. 1. The dam is structurally adequate to meet the conditions in ss. NR 333.05 (2) (k) and 333.07 (3) (b).

NR 116.08(3)(a)2. 2. The dam is hydraulically adequate to meet the standards in s. NR 333.07 (1).

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)(a)6. 6. The department reviews and approves the material submitted under subds. 1. to 5.

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;