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24 <br /> Coliform Bacteria is a standard indicator of drinking water quality used to indicate <br /> whether a well is properly protected from biological contaminants. Total coliform and <br /> fecal coliform are associated with the intestinal tract of warm-blooded animals and are <br /> not considered to be harmful, but are used by the labs as indicator bacteria for the <br /> presence of other, harmful bacteria. The presence of coliform bacteria indicates that <br /> surface water contamination is present in a well, either through a shallow, unprotected <br /> vein of water (generally less than 60 feet from the ground surface), or from an <br /> inadequate length of casing or other well construction deficiency. Current Orange <br /> County well construction standards require at least 63 feet of casing on all new drilled <br /> wells. Since enacting this requirement, there has been a marked decrease in the <br /> instances of fecal coliform contamination of new wells.3 <br /> Bacteria- Orange County <br /> Fecal <br /> Coliform Total <br /> 4% Coliform <br /> 32 <br /> Bact er i a N_1459 <br /> Absent <br /> 64% <br /> Figure 12, B3-2: Presence of bacteria in Orange County wells <br /> Because coliform is used as an indicator of contamination, a well with persistent coliform <br /> bacteria or with fecal coliform present should be considered an unsafe source of drinking <br /> water. The presence of coliform indicates that conditions are favorable for the presence <br /> of other bacteria that can cause health problems such as diarrhea, upset stomach, <br /> cramps, and vomiting.4 <br /> Arsenic is a naturally occurring element in the soil and rock formations that can leach <br /> into the groundwater. It can also be associated with agricultural activities and various <br /> industrial processes. Arsenic found in the groundwater of Orange County is considered <br /> to be naturally occurring as there are few industrial sources of arsenic in the county.5 <br /> The EPA recommended drinking water limit for Arsenic is 0.01 mg/I, however the NC <br /> Department of Environment and Natural Resources recommends a limit of 0.00002 mg/I. <br /> The lowest level of Arsenic that the state public health laboratory can detect is 0.001 <br /> mg/I <br /> 3 Orange County Health Department.Cancer Prevalence Assessment Water Quality Assessment Mill Creek <br /> Road Area. <br /> 4 Ibid <br /> 5 Ibid <br />