Ohio Admin. Code 1501:21-3-01 - Definitions

The following definitions shall apply to the terms used in division 1501:21 of the Administrative Code:

(A) "Applicant" means the individual, corporation, partnership, proprietor, or public agency which is making an application for a construction permit.

(B) "Appurtenant works" means interrelated elements or components of the dam including but not limited to outlet works and spillway channels.

(C) "Breach" is defined as an opening in a dam that prevents the dam from impounding a significant amount of water.

(D) "Bulkhead" means a structure or partition to reduce pressure and shut off water from entering a valve or gate chamber to allow for repair and maintenance of the valve or gate.

(E) "Chief" means the chief of the division of water resources of the department of natural resources, state of Ohio.

(F) "Conveyance" is the hydraulic term applied to the measurement of the carrying capacities of stream channels and overbank areas. Conveyance is directly proportional to discharge.

(G) "Critical flood" means the flood that would result in no additional loss of life, health or property along a critical routing reach downstream of the dam from overtopping failure of the dam when compared to the potential for loss of life, health or property caused by the flood in the absence of a dam overtopping failure.

(H) "Critical routing reach" means the entire floodplain area downstream of the dam where life, health, or property is potentially affected by failure of a dam.

(I) "Dam" means any artificial barrier together with any appurtenant works, which either does or may impound water or other liquefied material. Upground reservoirs and lagoons are considered to be dams. A fill or structure intended solely for highway or railroad use that does not permanently impound water or other liquefied material as determined by the chief is not considered a dam.

(J) "Design flood" is the runoff from the design storm taking into account the physiographic, topographic, hydrologic, and hydraulic characteristics of the drainage area.

(K) "Division" means the division of water resources of the department of natural resources, state of Ohio.

(L) "Emergency spill way" means a discharge system designed to operate at an elevation above the principal spill way to safely convey discharges that exceed the principal spill way's capacity without jeopardizing the safety of the dam.

(M) "Enlargement" means increasing the elevation of the top of an existing dam for the purpose of increasing the elevation of the normal pool level of the impoundment, or increasing the elevation of the top of an existing levee.

(N) "Flood" means a general and temporary condition of partial or complete inundation of normally dry land area.

(O) "Flood profile" means a graph or longitudinal plot of maximum water surface elevations of a flood event versus measured distance along a stream from a fixed point of reference.

(P) "Floodplain" means the land area adjoining a watercourse which may be inundated during a flood.

(Q) "Freeboard" means the vertical dimension between the top of the dam or levee (without camber) and the reservoir at normal pool level, maximum operating pool, or stream water surface.

(R) "Height-of-dam" means the vertical dimension as measured from the elevation of the natural stream bed, watercourse, or lowest ground elevation at the downstream or outside toe of a dam to the elevation of the top of the dam.

(S) "Length-of-dam" means the horizontal dimension as measured along the crest of the dam from natural abutment to natural abutment. Spillway systems over the dam but not in the abutment area are included in the length determination. For upground reservoirs the length is the continuous distance around the crest of the dam.

(T) "Levee" means any artificial barrier together with any appurtenant works that will divert or restrain the flow of a stream or other body of water for the purpose of protecting an area from inundation by flood waters.

(U) "One-hundred-year flood" means the flood having a one per cent probability of being equaled or exceeded in any given year.

(V) "Overtopping" means an event that occurs when the pool or stream elevation exceeds the elevation of the top of a dam or levee.

(W) "Owner" means those who own, or propose to construct a dam or levee.

(X) "Pipe conduit" means any tube or hollow channel which conveys water to or from a reservoir, or through a levee.

(Y) "Primary or principal spillway" means the first discharge system designed to begin operation after the normal design storage capacity has been exceeded.

(Z) "Probable maximum flood" or "PMF" means the flood that may be expected from the most severe combination of critical meteorologic and hydrologic conditions that are reasonably possible in the drainage basin under study. The "PMF" is derived from the probable maximum precipitation and is determined by using a hydrologic model to simulate the drainage basin's response to those critical conditions which produce the most severe flood runoff.

(AA) "Probable maximum precipitation" or "PMP" means theoretically, the greatest depth of precipitation for a given duration that is physically possible over a given size storm area at a particular geographic location. The "PMP" is determined on the basis of data obtained by the national oceanic and atmospheric administration or other sources accepted by the chief.

(BB) "Reservoir" means any impoundment, or any potential impoundment, that will be created by a dam.

(CC) "Spillway level" means the elevation of the primary (principal) spillway or the elevation of the top of the dam if there is no spillway.

(DD) "Storage volume" or "storage capacity" means the volume of water or other liquefied material, which is or may be impounded by a dam at a given elevation above the natural stream bed or above the natural grade for upground reservoirs. Impounded material that can be shown to the satisfaction of the chief to be non-liquefied can be excluded from the storage volume.

(EE) "Total storage volume" means the total volume of water or other liquefied material impounded when the pool level is at the top of the dam immediately before it is overtopped. Impounded material that can be shown to the satisfaction of the chief to be non-liquefied can be excluded from the total storage volume.

(FF) "Upground reservoir" means a reservoir formed by artificial barriers on two or more sides and which impounds water or liquefied material pumped or otherwise imported from an exterior source. Lagoons are considered upground reservoirs.

Notes

Ohio Admin. Code 1501:21-3-01

Effective: 6/27/2024
Five Year Review (FYR) Dates: 3/3/2028
Promulgated Under: 119.03
Statutory Authority: 1521.06
Rule Amplifies: 1521.06, 1521.061, 1521.062
Prior Effective Dates: 04/15/1972, 10/15/1981, 12/09/1999, 01/16/2005, 05/23/2010, 05/24/2018