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Groundwater models <br /> ' The District has historically relied on the use of a local-scale groundwater model to evaluate <br /> potential impacts of groundwater withdrawals at Indian River County's public supply wellfrelds. <br /> Honorable, Gary Wheeler, Chairman <br /> January 2, 2007 <br /> Page Two <br /> ' This model, which was prepared by Dr. David Toth, a District staff member, was mentioned at <br /> the workshop. This model, although useful for evaluations of the impacts of groundwater <br /> withdrawals from the wellfields, has limited usefulness for evaluating the impacts of withdrawals <br /> throughout Indian River County and surrounding areas. A new model that is designed for <br /> evaluations of withdrawals throughout the larger area is in preparation and is scheduled to be <br /> ready for use in late spring 2007. Hydrologic information included in the local-scale model will <br /> be considered during preparation of the regional-scale model. The District anticipates the use of <br /> the regional-scale model in the 2008 District Water Supply Assessment. <br /> Increased withdrawals at the south water treatment :plant wellfield <br /> The County' s current consumptive use permit for withdrawals from the County' s south water <br /> treatment plant wellfield is limited in quantity because of concerns that withdrawals from this <br /> wellfield could cause water levels in wells used for citrusurrigation in St. Lucie County in the <br /> South Florida Water Management District (SFWMD) to decline such that flows of water to <br /> support existing uses would reduced by 10% or more. Until recently, SFWMD would not allow <br /> the placement of pumps on irrigation wells in St. Lucie County. Therefore, the projected water <br /> level declines of about one foot, which were associated with previously proposed increased <br /> withdrawals from the Floridan aquifer at the County ' s south water treatment well field, would <br /> have resulted in a significant reduction of the natural flow of water from wells that are used as a <br /> source for citrus irrigation. Recent changes in SFWMD permitting procedures may allow for <br /> increased withdrawals from the wellfield. The District recommends that the County staff meet <br /> with District staff at the Palm Bay Service Center to discuss the possibility of amending the <br /> current permit to provide for increased groundwater withdrawals at the south wellfield. District <br /> staff can coordinate with SFWMD staff as necessary concerning this matter. <br /> Withdrawals from the north water treatment plant wellfield <br /> The District appreciates the concern the County has shown for the potential impacts of increased <br /> groundwater withdrawals at the County's north water treatment plant wellfield. In order to <br /> address these concerns and be in a position to provide additional supplies should the <br /> development of alternative sources not be able to keep pace with growth, the District suggests <br /> that the County investigate the feasibility of installing six new wells instead of three. These six <br /> wells could be spaced further apart than currently planned and could be outfitted with lower <br /> capacity pumps. This would allow for the same production capacity but would reduce potential <br /> water level and water quality impacts. These wells could be constructed with 16 inch casing, <br /> which would allow for the installation of larger capacity pumps in the future should the potential <br /> interference issues be resolved. <br />