Illinois Administrative Code
Title 17 - CONSERVATION
Part 3702 - CONSTRUCTION AND MAINTENANCE OF DAMS
Section 3702.20 - Definitions

"As-Built Plans" A set of plans marked to show all deviations from the permitted construction plans.

"Construct" To erect, build, emplace, or remove a structure capable of storing or diverting water.

"Corps Guidelines" The U.S. Army Corps of Engineers' "Recommended Guidelines for Safety Inspection of Dams" which is Appendix D of ER 1110-2-106, National Program for Inspection of Non-Federal Dams, 33 CFR 222, as of July 1, 1983, not including any later amendments or editions.

"Dam" All obstructions, walls, embankments, or barriers, together with their abutments and appurtenant works, if any, constructed for the purpose of storing or diverting water or creating a pool. Not included are underground or elevated tanks to store water.

"Dam Abutment" The intersection of the left or right side of the dam embankment with natural ground surface.

"Dam Height" Height of the dam in feet as measured from the natural bed of the stream or water course at the downstream dam slope toe of the barrier to the top of the embankment or barrier.

"Department" The Illinois Department of Natural Resources.

"Director" The Director of the Illinois Department of Natural Resources or his/her designated representative.

"Drawdown" The magnitude of the change in surface elevation of a lake or body of water as a result of the withdrawal of water therefrom.

"Engineer" A structural and/or professional engineer registered in the State of Illinois, under the Professional Engineering Practice Act [225 ILCS 325 ] and the Structural Engineers Act [225 ILCS 340 ], with expertise in the investigation, design, construction, and operation of dams.

"Flood Plain" The land adjacent to a body of water which has been or may hereafter be covered by flood water.

"Freeboard" The difference in elevation between the top of dam and the maximum water surface that would be attained during the passage of the selected flood occurrence.

"Impounding Capacity" The total volume of water, expressed in acre-feet, that is stored in the reservoir above the natural bed of the stream or watercourse when the water surface is at the top of the embankment or barrier.

"In Conformance With All Applicable Standards Existing At The Time Of Its Construction" Built in accordance with an Illinois Department of Natural Resources, Office of Water Resources (or its predecessors) permit or having written verification from the Department of a permit not being required.

"In Good Repair" Maintained so as to be in sound condition, free from defect or damage which may hinder the structure's functions as designed.

"Major Modification" Major structural and/or hydraulic modification which involves extensive reconstruction of a dam and/or its appurtenances.

"Normal Pool" The water surface elevation corresponding to the elevation of the principal spillway crest in the case of an ungated spillway, or the top of the spillway gates in a closed position in the case of a gated principal spillway. A dam may have more than one normal pool if operating procedures require varying water surface elevations.

"OWR" The Illinois Department of Natural Resources, Office of Water Resources.

"PMF" The probable maximum flood. The flood that may be expected from the most severe combination of critical meteorologic and hydrologic conditions that are reasonbly possible in a region.

"Qualified Personnel" Federal or State personnel having the same experience as an engineer.

"Rural Areas" Areas of the State not classified as Urban Areas.

"Selected Flood Occurrence" That flood occurrence which corresponds to the recommended total spillway design flood for the particular classification of dam as defined in this Part.

"This Part" The Illinois Department of Natural Resource's Rules for "Construction and Maintenance of Dams" (17 Ill. Adm. Code 3702).

"Urban Areas" Areas of the State where residential, commercial or industrial development currently exists or, based upon adopted or proposed land use plans or controls, is expected to occur within ten years of the application date. In determining urban areas, the expertise of local officials, regional or local planning commissions, city and county planners, and private development planners, as well as all available mapping may be utilized. Areas with isolated or widely scattered buildings will generally not be classified urban areas.

"Urban Development" The residential, commercial or industrial use of flood plain areas, immediately upstream and downstream of a dam, excluding isolated farm buildings.

"Watershed" Total land area above a given point (e.g. a dam) on a stream or waterway that contributes runoff to that point.

"Wave Generation Height" The vertical distance between a crest and the preceding trough of a wave caused by wind blowing over a water surface or caused by mechanical methods such as waves generated by motor boats.