Prairie streams have low basin-average runoff, and are significantly impacted by human settlement. Recent studies have suggested that climate change has resulted in a 0.2% per year decrease in southern Alberta's late summer streamflow. However, even in river basins identified by the Water Survey of Canada as having 'natural' flow, more than 5% of the total runoff may be diverted and stored for rural activities. This is often unaccounted for in hydrological models or statistical analyses of streamflow trends. While the cumulative impact of these small water diversions is now recognized in water management decisions for major basins, it has not yet been incorporated into streamflow analyses. This paper highlights the cumulative effects of small water diversions and illustrates that they are at least as large as reported climate change effects, and must be accounted for in any streamflow analysis of Prairie streams. © 2012 Canadian Water Resources Association.