Agenda - 12-02-1996 - 15a - Laserfiche WebLink

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j 11 Conclusions Although a great deal of data and information is generated and used in the creation of this report, several basic findings can be highlighted from the report: • Approximately 41%of County residents depend on ground water for their drinking water supply. • Most of the ground water in Orange County is found in a geologic zone of weathered bedrock and soil,termed the"regolith" • The recharge to the ground water system is highest along a north-south zone in the center of the County,and lowest in the western and southeastern(Triassic basin)portions of the County. The Haw River basin in western Orange has the lowest mean recharge with 311 gallons/day/acre,while the Morgan Creek basin upstream of Chapel Hill has the highest rate at 477 gallons/day/acre. • A significant portion of streamflow in Orange County streams is ground water "baseflow",ranging from 48%in Morgan Creek upstream from Chapel Hill to 32% in New Hope River(Bolin Creek and the areas draining to Jordan Lake). • Mean recharge rates and recharge duration statistics(the percentage of time during which ground water flow meets or exceeds a specified amount)can be used for ground water management planning.Two examples are provided that illustrate ways data could be used to estimate a required recharge area.However, a number of assumptions are utilized in this approach that may be open to interpretation.The examples are provided as illustrations of ways that data can be used for planning purposes,rather than a standard template for application in review of individual sites. • Overall,there is considerable ground water available in Orange County,to varying degrees in the different basins.These resources can be relied upon to provide potable water to a significant part of the County's population,through careful planning and application of sound hydrogeologic principles. 8