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The claw correlation between the waters and the meteoric water line indicates minimal exchange of oxygen isotapes between waters and rocks. {tt takes s relatively large cock:water ratio far water-oxygen to exchange with rock-oxygen; this can be accomplished if a cansiderabl< amount of contact occurs between each parcel of water and s Isrge valume of rock, a process tha can be acquired through deep cntstal circulation over a long period of time.} This points to a relatively young age for the waters, although young in this case might be thousands of years as oppased to tens of thousands. Overall, the values azgue for relatively rapid recharge of the groundwater (thousands of years). Neverthaless, there is good evidence that some of the fault waters, notably a few Pram the Southeast Head gate fault and the t3 East Mains fault, have undergone some water:rack exchange prior to discharge in the underground mine. Variable mixtures of local meteoric water and fault water can resdily explain the range of SD and S'aO values in al! of the waters. The aD snd S'8O values of the NW panels sump and the Edw'srds mine portal are identical within analytical uncertainty. One might expect some shift along the meteoric water tine due to local meteoric water variations with season, but the virtually identical nature of these two samples in context of the physical circumstances supports the notion that they represent a mixtura containing meteoric water that is not only very local, but slso probably derived from snow ar rainfall that fell in the same season of the year. Insofar as the NW Panels sump water may represent the Edwards Portal seep water, it is clear that meteoric water mixing has occurred within or prior to reaching the sump. And althaugh other constituents require it, no further m'sxing is needed to explain the seep water composition, at least in terms of SD and b180 values. b"C. There is a signiticant shift in a"C values between the fault waters and the seep water. (The value of+24, which was reported for the S-seam sample, is probably a misprint; that value is more likely -24 or perhaps +2.4 or -2.4 900. This could significantly affect other interpretations. Generally, this analysis was disregarded.} Fault waters aze significantly heavier (range = -2.7 to +10.7950} th<'tn the seep water (-t 29 950). Several mechanisms might produce such a shift. Interactions with meteoric water can be called onto explain part of a shift from the heavy S"C fault waters to the light seep waters, because atmospheric C0: has a lighter S"G (about -7 per mil}. However, this obviously cannot account for alt of the shift. Safi gas GO;, evhich is considerably lighter {range = -10 to -30 9bo -• see values fn P. Defines, "The Isotopic Composition of Reduced Organic Carbon" in F. Fritz and J.Ch.Fontes, 1984, Handbook of Environmental Isotope Geochemistry, Elsevier. p. 329-434} could aecaunt for all of [he shift to tighter values, provided enough sail water was encountered. A single "Hsrren member" sample, which has a &''C value of -9.~ no, and which is very close in eomposstian to the seep waters, can also help explain part of the shift to tighter values, but not all of the shift, assuming this value is representative oY the unit as a whole. (Variation in F3-seam S"C values would be useful to knave as would variations in the sump waters.) If the single B-seam value, which was reported at +24 ~~, were actually -24 900, there would very little need to call an high amounts of light carbon From sail gases or ether sources.