South Dakota Administrative Rules › Title 74 - Department of Environment And Natural Resources › Article 74:02 - Water rights › Chapter 74:02:08 - Safety of dams › Section 74:02:08:01 - Definitions

Current through Register Vol. 51, page 10, July 15, 2024
Terms defined by SDCL 46-1 to 46-7, inclusive, have the same meaning
	 when used in this chapter. In addition, terms used in this chapter mean:
(1) "Area capacity curves," graphic curves
  which show the relationship between reservoir surface area and the storage
  capacity of the reservoir at given elevations;
(2) "Breach analysis," a simulated dam
  failure performed to determine the outflow hydrograph and to route the
  resulting flood wave;
(3) "Category
  1 dam," a high hazard dam whose failure may cause loss of life;
(4) "Category 2 dam," a significant hazard
  dam whose failure may cause damage to buildings, highways, railroads, bridges,
  or public utilities; loss of a water supply reservoir for a water distribution
  system; other extensive economic loss; or the reservoir is the only source of
  water for a water distribution system;
(5) "Category 3 dam," a low hazard dam whose
  failure may cause limited damage to agricultural lands or county and township
  roads or minimum economic loss;
(6)
  "Conservation storage capacity," the volume in acre-feet in the reservoir at
  the crest of the primary spillway;
(7) "Dam," for the purpose of this chapter an
  artificial barrier, including appurtenant works, which impounds or diverts
  water and which is 25 feet or more in height from the natural bed of the stream
  or watercourse measured at the downstream toe of the barrier or from the lowest
  elevation of the outside limit of the barrier, if it is not across a stream
  channel or watercourse, to the maximum water storage elevation or has an
  impounding capacity at maximum water storage elevation of 50 acre-feet or more.
  A barrier is not considered a dam for the purpose of this chapter if the height
  does not exceed 6 feet regardless of storage capacity or if the storage
  capacity at maximum water storage elevation does not exceed 15 acre-feet
  regardless of height;
(8)
  "Effective height," the difference in elevation in feet between the lowest
  point in the cross section taken along the centerline of the dam and the crest
  of the emergency spillway. If there is no emergency spillway, the top of the
  dam is the upper limit;
(9)
  "Emergency preparedness plan," "EPP," a predetermined plan of action to be
  taken to reduce the potential for property damage and loss of lives in an area
  that may be affected by a dam break;
(10) "Engineer," a person who is registered
  as a professional engineer pursuant to SDCL 36-18, or a person who is employed
  by a federal or state agency and who designs or inspects dams as part of the
  person's employment, acting under the supervision of a professional engineer
  registered pursuant to SDCL 36-18;
(11) "Freeboard," the vertical distance
  between the top of the dam and the estimated maximum water level;
(12) "Height," the difference in the
  elevation of either the natural bed of the stream or watercourse or the lowest
  point on the toe of the dam, whichever is lower, and the crest elevation of the
  dam;
(13) "Inspection," a visual or
  mechanical check by measuring, boring, or any method necessary to determine the
  adequacy of construction techniques and the safety and operating performance of
  a dam;
(14) "Intermediate storage
  capacity," the volume in acre-feet in the reservoir at the crest of the
  emergency spillway;
(15) "Maximum
  storage capacity," the volume in acre-feet in the reservoir at the crest of the
  dam;
(16) "Owner," "dam owner," a
  person as defined by SDCL
  46-1-6(1) who
  owns, controls, operates, maintains, manages, or proposes to construct a dam or
  reservoir;
(17) "Preliminary risk
  assessment," as applied to dam safety, the process of identifying the
  downstream hazard potential for the purpose of classifying a dam;
(18) "Probable maximum flood," "PMF," the
  flood that may be expected from the most severe combination of critical
  meteorologic and hydrologic conditions that are possible in the
  region;
(19) "Probable maximum
  precipitation," "PMP," the precipitation that may be expected from the most
  severe combination of critical meteorologic conditions that are reasonably
  possible in an area as found in the National Weather Service
  Hydrometeorological Report No. 51, "Probable Maximum Precipitation Estimates,
  United States East of the 105th Meridian"; or Hydrometeorological Report No.
  55, "Probable Maximum Precipitation Estimates, United States Between the
  Continental Divide and the 103rd Meridian";
(20) "Process water," water that may have
  chemicals, sewage, metals, or any other material added to it during the use of
  the water in an operation;
(21)
  "Risk assessment," as applied to dam safety, the process of identifying the
  likelihood and consequences of dam failure to provide the basis for informed
  decisions on a course of action;
(22) "Spillway," an open or closed channel,
  conduit, or drop structure used to convey water from a reservoir.
(23) "Spillway design flood," the flood that
  the spillway of a given project is designated to pass safely without
  overtopping the structure;
(24)
  "25-year, 24-hour duration flood," the flood magnitude expected to be equaled
  or exceeded on the average of once in 25 years, with a four percent chance of
  being exceeded in any given year, determined by using the 25-year, 24-hour
  storm unless gauging data is available and proved to be accurate;
(25) "50-year, 24-hour duration flood," the
  flood magnitude expected to be equaled or exceeded on the average of once in 50
  years, with a two percent chance of being exceeded in any given year,
  determined by using the 50-year, 24-hour storm unless gauging data is available
  and proved to be accurate;
(26)
  "100-year flood," the flood magnitude expected to be equaled or exceeded on the
  average of once in 100 years, with a one percent chance of being exceeded in
  any given year, determined by using the 100-year, 24-hour storm unless gauging
  data is available and proved to be accurate.
General Authority:
SDCL
		46-2-5,
		46-7-3.
Law Implemented:
SDCL
		46-1-6,
		46-1-15,
		46-5-10,
		46-5-11,
		46-5-47,
		46-7-3,
		46-7-5.
Hydrometeorological Report No. 51, "Probable Maximum Precipitation
		Estimates, United States East of the 105th Meridian," June 1978, Reprinted
		August 1986; Hydrometeorological Report No. 55, "Probable Maximum Precipitation
		Estimates, United States Between the Continental Divide and the 103rd
		Meridian," March 1984, prepared by the Office of Hydrology, National Weather
		Service, National Oceanic and Atmospheric Administration, U. S. Department of
		Commerce. Copies may be obtained from the Division of Water Rights, Joe Foss
		Building, 523 East Capitol Avenue, at no
		cost.