Chapter NR 116

NR 116.02   Applicability.

NR 116.03   Definitions.

NR 116.05   Adoption and upgrading of floodplain zoning ordinances.

NR 116.06   Areas to be regulated.

NR 116.07   Standards for hydrologic and hydraulic studies.

NR 116.08   Uses downstream of dams.

NR 116.09   Data required to be shown on floodplain zoning maps.

NR 116.10   Conflicts between water surface profiles and floodplain zoning maps.

NR 116.11   Criteria for establishing and rezoning floodplain districts.

NR 116.12   Development standards in floodway areas.

NR 116.13   Development standards in floodfringe areas.

NR 116.14   Development standards in other floodplain areas.

NR 116.15   Nonconforming uses and nonconforming buildings.

NR 116.16   Floodproofing.

NR 116.17   Levees, floodwalls and channel improvements.

NR 116.18   Procedures for changing floodplain, floodway, floodfringe, shallow depth flooding, flood storage and coastal floodplain district limits.

NR 116.19   Appointment and duties of zoning administrator, zoning agency and board of adjustment or appeals.

NR 116.20   Municipal responsibilities.

NR 116.21   Permits, special exceptions, conditional uses, variances, appeals and amendments.

NR 116.22   Department duties.

Ch. NR 116 Note Note: Chapter NR 116 as it existed on February 28, 1986 was repealed and a new chapter NR 116 was created effective March 1, 1986.

NR 116.01 NR 116.01 Purpose.

NR 116.01(1) (1) The Wisconsin legislature in enacting chapter 614, laws of 1965, recognized that floodplain zoning is a necessary tool to protect human life, health and to minimize property damages and economic losses. Municipalities are required by s. 87.30 (1), Stats., to adopt reasonable and effective floodplain zoning ordinances within their respective jurisdictions to regulate all floodplains where serious flood damage may occur within one year after hydraulic and engineering data adequate to formulate the ordinance becomes available. If a municipality has a floodplain zoning ordinance already in effect, the provisions in s. NR 116.05 shall apply.

NR 116.01(2) (2) The purpose of these rules is to provide a uniform basis for the preparation and implementation of sound floodplain regulations for all Wisconsin municipalities, to:

NR 116.01(2)(a) (a) Protect life, health and property;

NR 116.01(2)(b) (b) Minimize expenditures of public monies for costly flood control projects;

NR 116.01(2)(c) (c) Minimize rescue and relief efforts, generally undertaken at the expense of the general public;

NR 116.01(2)(d) (d) Minimize business interruptions;

NR 116.01(2)(e) (e) Minimize damage to public facilities such as water mains, sewer lines, streets and bridges;

NR 116.01(2)(f) (f) Minimize the occurrence of future flood blight areas;

NR 116.01(2)(g) (g) Discourage the victimization of unwary land and home buyers; and

NR 116.01(2)(h) (h) Prevent increases in the regional flood from occurring which will increase flood damage and may result in conflict and litigation between landowners.

NR 116.01 History History: Cr. Register, February, 1986, No. 362, eff. 3-1-86.

NR 116.02 NR 116.02 Applicability. The provisions of this chapter are applicable to all municipalities.

NR 116.02 Note Note: Corps of engineers dredged material disposal activities which are authorized pursuant to s. 30.202 (2), Stats., are exempt from the requirements of this chapter.

NR 116.02 History History: Cr. Register, February, 1986, No. 362, eff. 3-1-86; CR 23-060: am. Register July 2024 No. 823, eff. 8-1-24.

NR 116.03 NR 116.03 Definitions. In this chapter:

NR 116.03(1) (1) “Accessory structure or use” means any facility, structure, building or use which is accessory or incidental to the principal use of a property, structure or building.

NR 116.03(1e) (1e) “Campground” means any parcel of land which is designed, maintained, intended or used for the purpose of providing sites for nonpermanent overnight use by 4 or more camping units, or which is advertised or represented as a camping area.

NR 116.03(1s) (1s) “Camping unit” means any portable device, no more than 400 square feet in area, used as a temporary shelter, including but not limited to a camping trailer, motor home, bus, van, pick-up truck or tent.

NR 116.03(2) (2) “Certificate of compliance” means a document that is issued to a property owner by a municipality certifying that the use of land or a building is in conformance with provisions of the floodplain zoning ordinance.

NR 116.03(3) (3) “Channel” means a natural or artificial watercourse with definite bed and banks to confine and conduct the normal flow of water.

NR 116.03(4) (4) “Coastal floodplain” means an area along the coast of Lake Michigan or Lake Superior which is inundated by the regional flood and which is also subject to additional hazards due to wave runup.

NR 116.03(5) (5) “Conditional use” or “special exception” means a use which is not allowed unless certain conditions specified in the zoning ordinance are met and a permit is granted by the board of adjustment or appeals or, where appropriate, the zoning agency.

NR 116.03(6) (6) “Dam” as defined in s. NR 333.03 (2) means any artificial barrier, together with appurtenant works, built across a waterway and which has the primary purpose of impounding or diverting water.

NR 116.03(6m) (6m) “Deck” means an unenclosed exterior structure that has no roof or sides, but has a permeable floor which allows the infiltration of precipitation.

NR 116.03(7) (7) “Department” means the Wisconsin department of natural resources.

NR 116.03(8) (8) “Developed area” means an area within a floodplain designated by a municipality and approved by the department which contains a minimum of 20 potential residential lots or a minimum of 5 acres of land zoned commercial, industrial or institutional wherein existing structures constitute a minimum of 50% of the structures that could be accommodated by the respective zoning density. The limits of the developed area are defined by a line connecting the existing structures on the outer perimeter of the majority of the structures. Vacant lots within that boundary are treated the same as lots with existing structures.

NR 116.03(9) (9) “Development” means any artificial change to improved or unimproved real estate, including, but not limited to, the construction of buildings, structures or accessory structures; the construction of additions or substantial improvements to buildings, structures or accessory structures; the placement of buildings or structures; mining, dredging, filling, grading, paving, excavation or drilling operations; and the storage, deposition or extraction of materials.

NR 116.03(10) (10) “Dryland access” means a vehicular access route which is above the regional flood elevation and which connects land located in the floodplain to land outside the floodplain.

NR 116.03(11) (11) “Erosion” means a wearing away of land by the action of natural forces such as wind or water; on a coastal floodplain, the carrying away of soil by wave action.

NR 116.03(12) (12) “Flood” or “flooding” means a general and temporary condition of partial or complete inundation of normally dry land areas caused by:

NR 116.03(12)(a) (a) The overflow or rise of inland waters;

NR 116.03(12)(b) (b) The rapid accumulation or runoff of surface waters from any source;

NR 116.03(12)(c) (c) The inundation caused by waves or currents of water exceeding anticipated cyclical levels along the shore of Lake Michigan or Lake Superior; and

NR 116.03(12)(d) (d) The sudden increase caused by an unusually high water level in a natural body of water, accompanied by a severe storm, or by an unanticipated force of nature, such as a seiche, or by some similarly unusual event.

NR 116.03(13) (13) “Flood frequency” means the probability of a flood occurrence. A flood frequency is generally determined from statistical analyses. The frequency of a particular flood event is usually expressed as occurring, on the average, once in a specified number of years or as a percent (%) chance of occurring in any given year.

NR 116.03 Note Note: For example, a 100-year flood event is expected to occur, or be exceeded, on the average of once in every 100 years, or which has a 1% chance of occurring or being exceeded in any given year. Any particular flood event could, however, occur more frequently than once in any given year.

NR 116.03(14) (14) “Floodfringe” means that portion of the floodplain outside of the floodway, which is covered by flood water during the regional flood. The term, “floodfringe” is generally associated with standing water rather than flowing water.

NR 116.03(15) (15) “Flood of record” means the highest known flood, the elevation of which can be determined through the use of physical or photographic data.

NR 116.03(16) (16) “Floodplain” means that land which has been or may be covered by flood water during the regional flood. The floodplain includes the floodway, floodfringe, shallow depth flooding, flood storage and coastal floodplain areas.

NR 116.03(17) (17) “Floodplain island” means a natural geologic land formation within the floodplain that is surrounded, but not covered, by flood water during the regional flood.

NR 116.03(18) (18) “Floodplain management” means the full range of public policy and action for insuring wise use of floodplains. It includes everything from the collection and dissemination of flood data to the acquisition of floodplain lands and the enactment and administration of codes, ordinances and statutes for land use in the floodplain.

NR 116.03(19) (19) “Floodproofing” means any combination of structural provisions, changes or adjustments to properties and structures, water and sanitary facilities and contents of buildings subject to flooding, for the purpose of reducing or eliminating flood damage.

NR 116.03(20) (20) “Flood protection elevation” means an elevation 2 feet above the regional flood elevation.

NR 116.03(21) (21) “Flood storage” means those floodplain areas where storage of flood waters has been taken into account in reducing the regional flood discharge.

NR 116.03(22) (22) “Floodway” means the channel of a river or stream, and those portions of the floodplain adjoining the channel required to carry the regional flood discharge.

NR 116.03(23) (23) “Freeboard” means a flood protection elevation requirement designed as a safety factor which is usually expressed in terms of a specified number of feet above a calculated flood level. Freeboard compensates for the effects of many factors that contribute to flood heights greater than those calculated. These factors include, but are not limited to, ice jams, debris accumulation, wave action, obstruction of bridge openings and floodways, the effects of urbanization on the hydrology of the watershed, loss of flood storage areas due to development and aggradation of the river or stream bed.

NR 116.03(24) (24) “Habitable building” means any building, or portion thereof used for human habitation.

NR 116.03(25) (25) “High flood damage potential” means potential damage as a result of flooding that is associated with any danger to life or health or any significant economic loss to a structure or building and its contents.

NR 116.03(26) (26) “Human habitation” means a human residence or dwelling.

NR 116.03(27) (27) “Hydraulic floodway lines” means those lines that delineate those portions of floodplain including the channel which are required to convey the regional flood discharge without any increase in regional flood heights.

NR 116.03(28) (28) “Increase in regional flood height” means a calculated upward rise in the regional flood elevation, equal to or greater than 0.01 foot, resulting from a comparison of existing conditions and proposed conditions which is directly attributable to development in the floodplain but not attributable to manipulation of mathematical variables such as roughness factors, expansion and contraction coefficients and discharge.

NR 116.03(29) (29) “Levee” means a continuous dike or embankment of earth constructed to prevent flooding of certain areas of land.

NR 116.03(30) (30) “Littoral drift” means the movement of sedimentary material along the Lake Michigan or Lake Superior shoreline due to wave action and water currents.

NR 116.03(30m) (30m) “Mobile recreational vehicle” means a recreational vehicle that is carried, towed or self-propelled; is licensed for highway use, if registration is required; and is always capable of being driven or towed by a licensed vehicle.

NR 116.03(31) (31) “Municipality” or “municipal” means a county, city or village.

NR 116.03(32) (32) “NGVD” or “National Geodetic Vertical Datum” means elevations referenced to mean sea level datum, 1929 adjustment.

NR 116.03(33) (33) “Nonconforming building” means an existing lawful building which is not in conformity with the dimensional or structural requirements of the floodplain zoning ordinance for the area of the floodplain which it occupies.

NR 116.03(34) (34) “Nonconforming use” means an existing lawful use or accessory use of a structure, building or development which is not in conformity with the provisions of the floodplain zoning ordinance for the area of the floodplain which it occupies.

NR 116.03(35) (35) “Obstruction to flow” means any development which physically blocks the conveyance of flood waters such that this development by itself or in conjunction with any future similar development will cause an increase in regional flood height.

NR 116.03(36) (36) “Official floodway lines” means those lines which have been approved by the department, adopted by the municipality, and which are shown on the official floodplain zoning maps and used for regulatory purposes. The official floodway lines are established assuming that the area landward of the floodway lines will not be available to convey flood flows.

NR 116.03(37) (37) “Open space use” means a use which has a relatively low flood damage potential, such as uses associated with agriculture, recreation, parking, storage yards, or certain sand and gravel operations.

NR 116.03(38) (38) “Private sewage system” means a sewage treatment and disposal system serving a single structure with a septic tank and soil absorption field located on the same parcel as the structure. This term also means an alternative sewage system approved by the department of industry, labor and human relations including a substitute for the septic tank or soil absorption field, a holding tank, a system serving more than one structure or a system located on a different parcel than the structure.

NR 116.03(39) (39) “Public utilities” means those utilities which employ underground or overhead transmission lines such as electric, telephone and telegraph, and distribution and collection systems such as water, sanitary sewer and storm sewer.

NR 116.03(40) (40) “Rapidly urbanizing watershed” means a watershed where more than 20% of the land area of the watershed has been developed for residential, commercial or industrial uses or where development of the watershed is projected to grow at a rate of 10% or more in the next 10-year period.

NR 116.03(41) (41) “Regional flood” means a flood determined to be representative of large floods known to have occurred in Wisconsin or which may be expected to occur on a particular lake, river or stream once in every 100 years.

NR 116.03 Note Note: The regional flood is based upon a statistical analysis of lake level or streamflow records available for the watershed or an analysis of rainfall and runoff characteristics in the watershed or both. The flood frequency of the regional flood is once in every 100 years. In any given year, there is a 1% chance that the regional flood may occur or be exceeded. During a typical 30-year mortgage period, the regional flood has a 26% chance of occurring.