Register April 2005 No. 592
Chapter NR 333
DAM DESIGN AND CONSTRUCTION
Submission of plans, specifications and analyses.
Dam hazard ratings.
Hydraulic design and safety requirements.
Ch. NR 333 Note
Note: Chapter NR 333 as it existed on May 31, 1985 was repealed and a new chapter NR 333 was created effective June 1, 1985.
The purpose of this chapter is to ensure that dams are designed, constructed and reconstructed so as to minimize the danger to life, health and property. This chapter is adopted pursuant to ss. 31.02 (2)
NR 333.01 History
Cr. Register, May, 1985, No. 353
, eff. 6-1-85.
The provisions of this chapter are applicable to dams not owned by the United States government that:
Have a structural height of more than 6 feet and a maximum storage capacity of 50 acre-feet or more of water.
Have a structural height of 25 feet or more and a maximum storage capacity of more than 15 acre-feet of water.
Have a structural height of 6 feet or less or a maximum storage capacity of less than 50 acre-feet of water if the department determines that the dam is likely to endanger life, health or property if it is not designed, constructed or reconstructed in accordance with this chapter.
All new and existing dams inspected, approved and licensed by a federal agency under 18 CFR Part 12
, are exempt from the provisions of this chapter provided that the dam meets requirements which are at least as restrictive as the requirements of this chapter.
NR 333.02 Note
Dams exempted from this chapter are still subject to the requirements of ch. 31
including, but not limited to, the requirements for permits and plan approvals.
NR 333.02 History
Cr. Register, May, 1985, No. 353
, eff. 6-1-85; CR 00-136
: am. Register July 2001, No. 547
Auxiliary spillway" means a secondary spillway designed to pass water only during flows exceeding the capacity of the principal spillway.
“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.
“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.
“Department" means the department of natural resources.
“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.
“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.
“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.
“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.
“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.
“Maximum headwater" means the maximum water surface elevation before overtopping would occur.
“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.
“Minimum tailwater" means the water level downstream from a dam at base flow.
“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.
“Overtopping" means the flow of water over parts of a dam which are not part of its spillway system.
“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.
“Principal spillway" means the primary structure for the discharge of normal flow through a dam.
" means the flood flow having a recurrence interval of 10 years or a 10% chance of occurring or being exceeded in any given year.
" means the flood flow having a recurrence interval of 50 years or a 2% chance of occurring or being exceeded in any given year.
" means the flood flow having a recurrence interval of 100 years or a 1% chance of occurring or being exceeded in any given year.
" 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.
" 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.
“Reconstruction" means alteration of an existing dam in a manner which affects its hydraulic capacity or structural integrity.
“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.
NR 333.03 Note
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.
“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.
“Submerged" means that the difference between the water surface elevations upstream and downstream from a dam is one foot or less.
“Total spillway capacity" means the sum of the auxiliary spillway and principal spillway capacities of a dam.
NR 333.03 History
Cr. Register, May, 1985, No. 353
, eff. 6-1-85; am. (25), Register, April, 1987, No. 376
, eff. 5-1-87; CR 00-136
: renum. (1) to (4), (9), (13) to (16), (21) to (25), (27) and (28) to be (2) to (4), (1), (8), (14) to (17), (20) to (26), am. (1), (3), (15), (24) and (26), r. (5), (8), (17), (20) and (26), cr. (5), (9) and (13) Register July 2001, No. 547
eff. 8-1-01; correction in (9) made under s. 13.93 (2m) (b) 7., Stats., Register January 2002 No. 553
Dam hazard rating.
The department shall assign a dam hazard rating according to the criteria in s. NR 333.06
for all dams subject to the provisions of this chapter. The assignment of a hazard rating shall be based on the findings of a dam failure analysis provided by the owner, pursuant to the standards of s. NR 333.05
, according to the following schedule:
For new dams, prior to granting permission or approval to construct.
For existing dams which are to be reconstructed, prior to granting permission or approval to reconstruct.
After a dam failure analysis has been approved by the department or is adopted in a floodplain zoning ordinance pursuant to s. 87.30
, Stats., and approved by the department.
Upon issuance of a department directive in a dam safety inspection report pursuant to s. 31.19
The design and construction of all new dams shall be in compliance with the requirements of this chapter.
The owners of all existing dams shall bring their dams into compliance with the requirements of this chapter within 10 years after being notified of the dam's hazard rating pursuant to sub. (1)
, unless ordered to do so earlier under s. 31.19 (5)