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f~~ <br />~ Page 2 <br />July 16, 2001 <br />This complex wetland ecosystem is supported by ground water inflow from the <br />south. Because the ground water aquifer is in sand substrate, supporting a thin <br />capillary fringe, the water table must be at or above the soil surface to support this <br />wetland. A permanent and directional lowering of the water table of 1-3 feet below <br />its present range of variation, and spring and summer levels, will cause the loss of <br />this wetland. <br />The report by John Gerstle of Hydrosphere Resource Consultants analyzed <br />potential water table declines on Sage Hill Farms using three scenarios of aquifer <br />transmissivity and pumping rate. However, from a wetland perspective all three <br />scenarios produce relatively similar water table changes under the Sage Hill Farm <br />wetland, and all are substantially greater than 1 ~ feet. All of John's models indicate <br />short-term water table declines of 20 feet or more under the wetland. This type of <br />drawdown will result in the rapid drying of your wetland, oxidation of the soils, and <br />the death of wetland plants. Under these circumstances, if the U.S. Army Corps of <br />Engineers were called out to do a wetland delineation, they would not call this site a <br />wetland. From an ecological perspective the wetland, as well as the pond located <br />just east of the wetland, would not longer support frogs, toads, and other aquatic I'rfe. <br />1 am also extremely concerned about the prospects of noxious weeds invading the <br />wetland area once it is dried up. In particular Canada thistle (Cirsium arvensis) is <br />most likely to invade and it is extremely difficult to eradicate, even if the site is wetted <br />again at a later time. This would severely degrade your land. <br />You asked me to address whether a wetland like yours could be maintained using <br />surface water inputs. Because this wetland is ground water connected, the flow of <br />water through the wetland has created many of the sites features. For example, the <br />Nebraska sedge community on the southern wetland edge is a typical spring <br />community occurring where ground water discharges to the surface. The main <br />community occupying the large central wetland area dominated by three-square <br />bulrush is also found in areas with high ground water tables. <br />Because the site has sandy soils, the application of surface water when the water <br />table is 20+ feet below the soil surface likely could not create and maintain a high <br />water table. The application of surtace water for wetland creation is only useful <br />where the wetland soil isfine-textured and water can be perched on the soil surface. <br />Also, the problems of bringing water to the site and distributing it on the site would <br />require the installation and maintenance of expensive ditches. Even with these <br />ditches the surtace soil infiltration rates like could not keep up with the loss of <br />ground water due to pumping at the Nix gravel mine. Therefore, it is unlikely that a <br />water table could be produced to replicate the type of wetland that occurs on your <br />farm today. Wetlands dominated by ponded surface water also tend to be <br />completely dominated by cattails, and do not produce the complex wildlife habitat <br />that you desire. <br />