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<br />The only target location with appreciable Ag concentrations ",..as ;\1ichigan Creek located at <br />10.700 ft some mil~ north of the large high-elevation valley knov.n as South Park. Most of the <br />AgI gencrators sitcd aoovc 9000 n were in South Park. Appendix B provides locations and <br />elevations of all generators as supplit.-d by \\'estem Weathcr Consultants. The e1e.....en South Park <br />generators in question are in the southeastern portion of Figure I \\ith elevations ranging Hum <br />8900..10.300 ft and a median near 9500 ft. Thcre is linle terrain blockage bern.ceo them and the <br />\1ichigan Creek location. L"pslopc v.ind now.. from the soul.hcast would be required to transport <br />the South Park Agl to ~ichigan Creek. It is not kno\\TI to the authors whether such local flows are <br />common during stonns. It is conceivable that Michigan Creek could be targeted \\ith northwC'st <br />flows. but that would seem unlikely since all other intervening target sites rccci\'t..-d little if any <br />~ing silver. <br /> <br />Whatever the conditions that resulted in silver deposition at Michigan Creek. the overall <br />target results mise quite St.'riOu.'i concerns about targeting. adequacy during the 2002/03 DWB <br />Sl..--cding program. Caution should. of course. be exercised in attempting to cxtmpolate ten point <br />samples to the entire intendcd target area. However. since all but one site were chosen by the <br />~'l.."<iing contractor as likely to be targeted. these tindings suggest littlc reason to believe that thc <br />overall intended target area was much better targeted then suggested by the results of Table 2. In <br />other WONS. pcrhaps something on the ordcr of 10 percent of the target area received significant <br />"seeding silver." It \..ill be rl.'Called that finding such silver does not necessarily mean that the <br />AgI se<.-tJing agent routincly enhanced snowfall because scavcnging by natund snowfall and other <br />ml..'Chanisms can be expected to lransport some silver from Agl plumes to Lhe sno.....'JXl.ck. In view <br />of this physical result from state-of-the art trace chcmistI)' analyscs. any suggestion of positive <br />seeding ctTt."Ctivcr\(,."'Ss based on statistical methods should be considen..~ with caution. <br /> <br />An interesting outcomc is that one of the thrt."C controllocalions f'e<..'ei\'cd some SC't..-ding <br />silver \\ith a value of 17.2 ppt. The three control sites were all north of latitude 40.3 deg on <br />Figure I. While a large number of AgI generators wen: located generally to the south and <br />southWI..'Sl. all control-sampling sites were well north of the intended target an~a which extended <br />to about 40.0 deg latitude. These gencralors we're presumt.-d to be operated only during northwest <br />tlow. intcnd(,,-tJ to affcct sno\\faJl further to Lhe souLh and cast. <br /> <br />The Rabbit r:.ars Pass location at 9450 ft was the most northwestern snow-sampling site <br />on Figure I. The sample from there showed no silver above background. Thc site was on the <br />west (up\\ind) side of the Pass. helping to protect it from any Agl plumes which were transported <br />north or northwestward. The tv.'o nearest generators were about 20 miles south~1 and all others <br />were 30 or more miles distant. <br /> <br />Willow Cn.'Ck Pass also received no noticeable Ag increase although the ncarest <br />generator. number 22. was only 12 miles to the south.southeasL and a total of live generators <br />were within 20 miles. Thc \\'illo\\! Creek Pass sample was collectedju.q south of the Continental <br />Divide at 9500 ft. The nearest generator (22) was about 1100 ft lowcr and others nearby <br />generators were at still lowcr elevations. An AgI plume' from g.enerator 22. north of Gmnby. <br />Colorado. Yrould have to flow north-northwest up a narrow valle)'. which contains State Highway <br />125. Such transport apparently did nOI occur \\ith an)" significant freQuenc~. <br /> <br />,1 <br />