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Important Water Feature Definitions

Ch. 12, §§ 12-5


100-year flood
The frequency of a flood in order of magnitude that occurs, on average, once every 100-hundred years.
Any man-made change including but not limited to buildings, mining, dredging, filling, grading, paving, excavation or drilling.
Drainage course
Natural or man-made waterway that controls runoff to prevent flooding or creation of floodlands.
Temporary overflow of floodwater to lands not usually covered by water.  The inundation of water usually occurs from heavily precipitation and/or overflow from an adjacent watercourse.
Floodplain (100-year)
Relatively flat area or low lying land proximate to a water body that may have been or be covered by 100-year floodwaters.
Channels or areas adjacent to channels that function to discharge an ordinary or seasonal flood.  The upper limit to a floodway is marked by the ordinary high water mark of the channel.
Floodway (100-year)
Calculated area adjacent to floodway required to carry 100-year flood waters.
Inland lake or pond, a river or stream
  1. A river or stream with defined banks and visual evidence of a continued flow of water.
  2. A natural or permanent artificial lake that has definite banks and a surface area of water more than 5 acres.  Does not include lagoons for treating polluted water.
  3. A natural or permanent artificial pond with a surface area that is less than five acres.  Does not include lagoons for treating polluted water.  
Shallow sound, channel, or pond near a larger body of water.
Soil, sand, gravel, clay, peat, debris and refuse, or any other organic or inorganic material.
Ordinary high water mark
Water line between upland and bottomland that is maintained with the fluctuation of the water level.  Below the line there is a drastic change in vegetation and soil type, even if water is not present.
Damage from discharge or organic and/or inorganic substances in excess of water quality criteria.
Surface discharge of precipitation to a watercourse or low lying area of land.  Runoff tends to be greatest after a storm event or spring melting events of snow and ice.
Any intermittent or temporary operation which occurs annually and is subject to changes in weather, water level, or time of year.
Mainly non-aquatic land area adjoining a lake, stream, or water course above the ordinary high water mark.
Water table
Top level of an aquifer where water pressure is equal to atmospheric pressure.
Any waterway or other body of water that have well-defined banks regardless of continual or intermittent flow.
Region or land area peripherally bounded by a water divide and draining ultimately to a particular body of water.
Land characterized by the presence of water at a frequency and duration to support aquatic life.


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