Wisconsin Administrative Code › Department of Natural Resources › NR 300-399 - Environmental Protection - Water Regulation › Chapter NR 333 - Dam design and construction › Section NR 333.03 - Definitions

Current through June 24, 2024
(1) "Auxiliary spillway" means a secondary
				spillway designed to pass water only during flows exceeding the capacity of the
				principal spillway.
(2) "Base flow"
				means that part of the stream flow that is derived from groundwater and
				calculated as the 7-day low flow that occurs on an average of once in 2 years
				or has a 50% chance of occurring in any given year. The notation is
				Q7,2.
(3) "Dam" means any
				artificial barrier in or across a watercourse which has the primary purpose of
				impounding or diverting water. A dam includes all appurtenant works, such as a
				dike, canal or powerhouse.
(4)
				"Department" means the department of natural resources.
(5) "Development" means any artificial change
				to improved or unimproved real estate not related to allowable open space use
				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; and campgrounds.
(6)
				"Floodplain with the dam nonexistent" means that area of land downstream from a
				dam that would be inundated by water during the regional flood if the dam did
				not exist.
(7) "Floodway" means the
				channel of a river or stream and those portions of the floodplain adjoining the
				channel which are required to carry the regional flood discharge.
(8) "Hydraulic shadow" means that area of
				land downstream from a dam that would be inundated by water upon failure of the
				dam during the regional flood.
(9)
				"Land use controls in place" means future development within the hydraulic
				shadow is required to conform to the criteria specified in a zoning ordinance
				adopted and approved pursuant to s.
				87.30, Stats.,
				and also consistent with land use plans developed under s.
				66.1001,
				Stats., or through restrictive covenants, easements, or other appropriate legal
				arrangements between the owner of the dam and the owners of all property within
				the hydraulic shadow.
(10) "Maximum
				headwater" means the maximum water surface elevation before overtopping would
				occur.
(11) "Maximum storage
				capacity" means the volume of water in acre-feet capable of being stored behind
				a dam at the maximum water surface elevation before overtopping would
				occur.
(12) "Minimum tailwater"
				means the water level downstream from a dam at base flow.
(13) "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.
(14) "Overtopping"
				means the flow of water over parts of a dam which are not part of its spillway
				system.
(15) "Owner" means any
				individual, partnership, public utility, company, cooperative, trust,
				corporation, association, state or interstate agency, city, village, town,
				county or special purpose district such as a drainage district or a public
				inland lake protection and rehabilitation district which has title to or
				recorded easement for operation, maintenance and access to a dam or to the
				specific parcel of land on which a dam exists.
(16) "Principal spillway" means the primary
				structure for the discharge of normal flow through a dam.
(17) "Q10" means the flood flow having a
				recurrence interval of 10 years or a 10% chance of occurring or being exceeded
				in any given year.
(18) "Q50" means
				the flood flow having a recurrence interval of 50 years or a 2% chance of
				occurring or being exceeded in any given year.
(19) "Q100" means the flood flow having a
				recurrence interval of 100 years or a 1% chance of occurring or being exceeded
				in any given year.
(20) "Q500"
				means the flood flow having a recurrence interval of 500 years or a 0.2% chance
				of occurring or being exceeded in any given year.
(21) "Q1000" means the flood flow having a
				recurrence interval of 1000 years or a 0.1% chance of occurring or being
				exceeded in any given year.
(22)
				"Reconstruction" means alteration of an existing dam in a manner which affects
				its hydraulic capacity or structural integrity.
(23) "Regional flood" means a flood
				determined to be representative of large floods known to have occurred in
				Wisconsin and which may be expected to occur on a particular stream once in
				every 100 years.
Note: The regional flood is based upon a statistical analysis
				  of stream flow records available for the watershed or an analysis of rainfall
				  or 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.
(24) "Structural height" means the difference
				in elevation in feet between the point of lowest elevation of the top of the
				dam before overtopping and the lowest elevation of the natural stream or lake
				bed at the downstream toe of the dam.
(25) "Submerged" means that the difference
				between the water surface elevations upstream and downstream from a dam is one
				foot or less.
(26) "Total spillway
				capacity" means the sum of the auxiliary spillway and principal spillway
				capacities of a dam.