The paper was well-written, easily accessible and

The paper emphasizedthat surface water allocations from the Athabasca River used in oil sand miningare based solely on short-term records. The methods Sauchyn et al. employed weretree ring reconstruction in water-sensitive conifer species along the AthabascaRiver and instrumental hydrologic records. Declines in water flow were foundpresent in all reaches of the Athabasca River Basin, suggesting that currentlevels of extraction will not be sustainable long-term.The majorstrength of the paper was the inclusion of greater data ranges, which revealedpreviously unknown periods of draught. Sauchyn et al.

included tree ringchronology and instrumental records from 1111 and 1913 onward, respectively,whereas previous studies were limited to 50-year hydrologic record spans and 200-yeartree ring reconstruction.            The major weakness of the paper was the interpolation of small data gaps due to a lack of seasonal records. This missing data could lessen theaccuracy of future surface water allocations, considering climate oscillations occur during these periods which affect the amount of runoff from theRocky Mountains into the Athabasca River.            The paper was well-written, easily accessible andintegrated new approaches in its methods. However, it failed to address what isconsidered a sustainable level of water extraction and ways in which thissustainability could be achieved.This articlewas assigned in order to emphasize the consequences of surface waterexploitation, since the hydrosphere is an essential component of global biogeochemicalcycling.