Potential time trends for water levels in Lake Athabasca, Canada, were investigated with particular emphasis on a critical examination of the available hydrometric record and other confounding factors mitigating against reliable trend detection on this sytem. Four hydrometric stations are available on Lake Athbasca, but only the Lake Athabasca near Crackingstone Point (07MC003) site has suitable - albeit temporally limited (1960-2010) - records for a rigorous time series analysis of annual water levels. The examination presented herein provides evidence that the 2010 lake level dataset at 07MC003 is flawed and should not be included in any trend analyses. With the conclusion that 2010 lake levels on Lake Athabasca at station 07MC003 are erroneous, lake level time series regressions over various timeframes between 1960 and 2009 yield widely varying degrees of non-significance and slope magnitude / direction. As a further confounding factor against mechanistic time trend analyses of water levels on Lake Athabasca, a dam and rockfill weirs were constructed on the lake outlets during the 1970s in order to maintain elevated lake levels. Thus, the entire time series of lake levels on Lake Athabasca since filling of the reservoir behind the W.A.C. Bennett Dam (Lake Williston) began in 1968 can be described as experiencing substantial anthropogenic modification. Collectively, these influences - including problems in the hydrometric record - appear to sufficiently impact the annual lake level record as to prevent reliable trend analyses that unequivocally isolate natural factors such as climate change or any other anthropogenic factors that may be operative in the source watersheds.
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[v1] 2012-12-31 21:28:19
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