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• • I <br /> U.S. DEPARTMENT OF AGRICULTURE PAGE 3 OF 3 <br /> NATURAL RESOURCES CONSERVATION SERVICE 01/18/00 <br /> • <br /> WATER FEATURES <br /> Endnote -- WATER FEATURES--Continued <br /> Information on the extent of flooding based on soil data is less specific than that provided by detailed engineering <br /> surveys that delineate flood-prone areas at specific flood frequency levels. <br /> High water table (seasonal) is the highest level of a saturated zone in the soil in most years. The depth cc a <br /> seasonal high water table applies to undrained soils. The estimates are based mainly on the evidence of a saturated <br /> zone, namely grayish colors or mottles in the soil. Indicated in this report are the depth to the seasonal high <br /> water table; the kind of water table, that is, "Apparent", "Artesian", or "Perched"; and the months of the year that <br /> the water table commonly is high. A water table that is seasonally high for less than 1 month is not indicated in <br /> this report. <br /> An "Apparent" water table is a thick zone of free water in the soil. It is indicated by the level at which water <br /> stands in an uncased borehole after adequate time is allowed for adjustment in the surrounding soil. <br /> An -Artesian' water table exists under a hydrostatic beneath an impermeable layer. When the impermeable layer has been <br /> penetrated by a cased borehole, the water rises. The final level of the water in the cased borehole is characterized as <br /> an artesian water table. <br /> A "Perched" water table is water standing above an unsaturated one. In places an upper, or "Perchedn, water <br /> e is separated from a lower one by a dry zone. Only saturated zones within a depth of about 6 feet are <br /> cared. <br /> Ponding is standing water in a closed depression. The water is removed only by deep percolation, transpiration, <br /> evaporation, or a combination of these processes. <br /> This report gives the depth and duration of ponding and the time of year when ponding is most likely. Depth, duration, <br /> and probable dates of occurrence are estimated. <br /> Depth is expressed as the depth of ponded water in feet above the soil surface. Duration is expressed as "Very <br /> brief- if less than 2 days, -Brief- if 2 to 7 days, "Long" if 7 to 30 days, and "Very long" if more than 30 days. The <br /> informs tion is based on the relation of each soil on the landscape to historic ponding and on local information about <br /> the extent and levels of ponding. <br /> • <br />