18 February 2011

Water Resource Types

Lake/Reservoir(Freshwater): A constructed impoundment or natural body of freshwater of considerable size, whose open-water and deep-bottom zones (no light penetration to bottom) are large compared to the shallow-water (shoreline) zone, which has light penetration to its bottom.

Estuary: A body of water in which salt water from the ocean and fresh water from rivers and land drainage meet and mix, producing intermediate salinities.

River or Stream: A watercourse that flows at all times, receiving water from ground water and/or surface runoff or other streams or rivers. The terms "river" and "stream" are often used interchangeably, depending on the size of the water body and the region in which it is located.

Stream (intermittent): A watercourse that flows only at certain times of the year, receiving groundwater or surface waters; also, a watercourse that does not flow continuously, when water losses from evaporation or seepage exceed available stream flow at different reaches of the channel.

Stream (ephemeral): A watercourse that flows during and shortly after periods of high precipitation. Ephemeral stream water quality is often a concern because the short-lived pools often are the site of reproduction for amphibious organisms and some air-breathing fish. For the purposes of this program, ephemeral streams are combined with intermittent streams.

An order system was developed for streams based on tributary relationships. It follows:

  • 1st order stream - the uppermost stream that has no tributaries; a headwater
  • 2nd order stream - the stream formed below the intersection of two 1st order streams
  • 3rd order stream - the stream formed below the intersection of two 2nd order streams
  • 4th order and on, if needed.

The intersection of a stream with another of a lower order does not change the order of that stream below that intersection.

Wetlands: Wetlands are areas that are inundated or saturated by surface or groundwater at a frequency or duration to support, and that under normal circumstances do support, a prevalence of vegetation (hydrophytes) typically adapted for life in saturated soil conditions. Wetlands include the transitional areas between aquatic and terrestrial systems. To be classified as a jurisdictional wetland for Section 404 purposes by the U.S. Army Corps of Engineers or EPA, an area must exhibit each of the following three attributes:
  • Hydric soils.
  • Water table is at or above the surface, or within the root zone, for a significant period of time during the growing season.
  • Soil is saturated at a frequency and duration to foster the growth and reproduction of hydrophytic vegetation and inhibit flood-intolerant species. (40 CFR 232.2(r) - Section 404)
An area that does not exhibit all of the above attributes concurrently may still be recognized as a wetland by scientists for ecological reasons.

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