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