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<br />mediocre targl..'ting at locations suggested by the seeding contrdctor. the overall target area would <br />be unlikely to ha...e had bener success. <br /> <br />The Wcstern Weather list .....as examine-d for reasonable spatial distribution and overall <br />target coverage. and v..as judged 10 meet these criteria \\~II with a single exception. The list was <br />also examined for frequency of early season sno\\mc:lt by considering 16 representative SNOTEL <br />stations in and around the target area. March I st. ~arch 15th. April I st and April 15th readings <br />were extracted from many years of data at indit'idual stations. The- number of years with Icss <br />snow water L'qui...a1em on. for example. April 15th compared with April I st. dividt.-d by the years <br />of available observations. provided an approximation of the melt frequency during the first half <br />of April. Similar calculations were made for the first and last half of March at each station. As <br />cXfX'Ctcd. there was a general tendl..'ney for lower e1e'v3tion stations to have more frequent melt <br />during any lX'riod. However. local exposure. slope. aspect and other lactors an: also involved in <br />sno\.\melt. While most stations did not experience frequent melt during the lirst or last half of <br />March. there were exceptions. One of the 16 stations exceeded SO percent mclt during the first <br />half of March. three stations exceeded that threshold during the last half of March and 7 <br />exceeded SO percent melt during the first half of April. Care was taken to avoid frequcnt melt <br />stations. <br /> <br />Thc final list of target silvcr-in-snow sampling stations is given in Table I below. from <br />south to north. followed by the three control sites. The laner werc sclt.~ted by the authors of this <br />report. All target locations but Sundance were recommcnded by Western Weathcr Consultants. <br />Inclusion of Sundance provided bcttcr spatial balance to the overall sampling network. It was the <br />eastcmmost station in an othernise unsampled region. .....hich appeared to have the potential for <br />targeting by several SlXding gt::ncrdtors. A large-scale topographic map \...ith all seeding <br />gent:rators. snow courses and SNOTEI. sitcs was used in judging spatial covcrage of the likely <br />target area. <br /> <br />Bl."Cause it is crucial that all snow samples be takcn before spring melt has begun. the <br />available historical record (1971-2001) was used to calculate the frequency of March melt. This <br />was donc for each of thc target sites by subtracting nearb)i March I st snow water equivalent <br />readings from those on April IS!. The frequency of March mclt was 7..cro in all cases except tor <br />Sundancc with 23 percent March mdt and \fiddle Fork Camp Ground with 6 percent. <br />Accordingly. snow samples near these stations were obtainl.-d before mid-March. A series of <br />heavy snov.falls after mid-March delayed planned sampling of several of the stations. but also <br />insured that snov.melt .....as not a signiticant factor before sampling was accomplished at all <br />stations. <br /> <br />3.2 Samplin~ Procedures <br /> <br />Thc trdCe chemistry as.."C'ssment U&."'d bulk seasonal snow samples collected at thc cnd of the <br />Sl.'Cding sea<;on. and prior to the start of the melt at individual stations. In addition. three sampling <br />site; were selected for control purpoSl.'S in areas exp..'Cted to be up\\ind and. therefore. free from <br />contamination by Agl seeding operations. Samples from ~ three stations were intended to serve <br />as a check on past measurements of background or natuml silvcr conccntrntions in mountain SOlm <br /> <br />15 <br />