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

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t 10 same time, however,most wastewater systems are not designed to provide ground water recharge,and a significant portion of wastewater return may be lost to evapo-transpiration. • Additional adjustments for changes in infiltration capacity of the land may increase the needed recharge area.For example,conversion of land from permanent seldom-grazed pasture or woodland to maintained lawns may reduce infiltration capacity by 50-60%and require a subsequent increase in recharge area. The above issues are subject to challenge and interpretation. Further research and study will be required on these issues before the approach outlined in this example could be put into use. Findings that ground water demand is lower than assumed(lower per capita use rates, lower person/dwelling rates, inclusion of wastewater return)could result in an average recharge area that is smaller than that shown in the example. On the other hand,conservative estimation of ground water demand and use can produce a more reliable water supply and help preserve stream base flow rates The second example assumes that there is site-specific data available for a proposed community water system.Here,test wells have been drilled and recharge duration statistics are used to estimate the amount of land needed for recharge of the community wells. Further research will be needed in this area to determine the implications for developments that utilize community wells.. Again, it should be noted that conditions on a particular tract may not be typical of an entire basin, so these examples should be considered as part of a basin-wide analysis only. Next As phase one of the Water Resources Committee's ground water resource investigation,this report provides new information about the rate of recharge to ground water in Orange County. The examples shown illustrate ways that ground water data may be used for management of the resource.However,this study is only an overview of average recharge rates in 12 basins.Use of these approaches will require additional information not currently known about the County's ground water resources. To further the knowledge of ground water resources,the Water Resources Committee will be proposing a scope of work to take the next step toward investigating the availability of ground water.Although a site-specific level of data about ground water availability will not be cost- effective,the second phase of the ground water investigation will work toward the creation of a "contour map"of ground water availability by analysis of test wells and other hydrogeologic research.This phase of the study will be presented to the Board of Commissioners at the December 7, 1996 Goal-Setting Retreat. 7