Section 3706.1210  Definitions

Unless specifically defined below, words or phrases used in this Part shall be interpreted so as to give them the meaning they have in common usage and to give this Part its most reasonable application.

"Authorized Flood Control Project" – A project which all authorizations required by law for construction, including any required for expenditure of construction funds, have been secured.

"Channel" – A natural or artificial watercourse of perceptible extent, with definite bed and banks to confine and conduct continuously or periodically flowing water.  The top of the banks form dividing lines between the channel and the overbank portion of the flood plain.

"Construction" – The placement or erection of structures or earthworks; land filling, excavation or other non-agricultural alternation of the ground surface; installation of public utilities; channel modification; storage of materials or any other activity undertaken to modify the existing physical features of a flood plain with respect to the storage and conveyance of flood waters.

"Conveyance" – Capacity of the valley cross section to discharge flood flows at the regulatory flood stage.

"Encroachment Limit" – A smoothed line based on hydraulic analysis indicating the maximum channelward encroachment which may be undertaken without significantly increasing flood stage.  The encroachment limit forms the common boundary of the flood fringe and regulatory floodway. On small streams and steepwalled valleys, the encroachment limit may coincide with the boundary of the regulatory flood plain.

"Equal Degree of Encroachment" – A method of determining the location of encroachment limits so that flood plain lands on both sides of a stream are capable of conveying a proportionate share of flood flows.  This is determined by considering the effect of encroachment on the hydraulic efficiency of the flood plain along both sides of a stream for a significant reach.

"Flood" – A temporary rise in stream level that results in inundation of areas not ordinarily covered by water.

"Flood Damage Potential" – Susceptibility to economic loss caused by flooding, such as inundation and damage to contents, structural damage, loss of occupancy or use, or interruption of normal services.  Threats to health and safety such as contamination of public water supplies, danger of drowning or electrocution, interruption of emergency services caused by flooding, failure of on-site waste disposal, and blighting of structures. Nuisances to adjacent lands caused by sediment or erosion, or the flotation of materials which may jam bridges or litter other lands.

"Flood Fringe" – Those portions of the regulatory flood plain outside the regulatory floodway.  Structures and fill placed within the flood fringe will not significantly increase flood stages.  The flood fringe could be quite wide on large streams, quite small or nonexistent on small streams.

"Flood Plain" – That land adjacent to a body of water which has been or may be hereafter covered by flood water including but not limited to the regulatory flood.

"Pollution" – Pollution shall be as defined in the Environmental Protection Act [415 ILCS 5] or the Rules and Regulations enacted under that Act (35 Ill. Adm. Code).

"Regulatory Flood Plain" – That land adjacent to a body of water with ground surface elevation at and below the regulatory flood elevation.

"Regulatory Flood Profile" – A graph showing the relationship of water surface elevation of the regulatory flood to location along the stream.

Regulatory Flood Protection Elevation" – An elevation of one foot above the regulatory flood elevation which provides freeboard protection against ice jams, waves, and debris.

"Regulatory Flood Stage" – The water surface elevation to be expected during discharge of the regulatory flood.

"Regulatory Floodway" – That portion of the regulatory flood plain required to store and convey the flood water of the regulatory flood with no significant increase in stage.

"Storage" – The volume between the regulatory flood stage and the ground surface.  The area measured on a valley cross section is a representation of the storage at that section.

(Source:  Amended at 3 Ill. Reg. 29, p. 192, effective July 21, 1979)