Figure 4: Combined plots of the six identified flow metrics assessed for the Barossa Valley Gorge (Yaldara gauging station) in the Barossa PWRA showing the environmental water requirement bounds (blue dashed lines) identified as the upper and lower limits of the three year moving average between 1997 and 2016 (orange dashed line). Grey points are metric results for the baseline period. The moving average post 2016 (black dashed line) showing current variability in the flow regime. For years where the moving average is outside the expected bounds, the data point is red, if it is inside the bounds, the data point is green, regardless of the actual position of the data point relative to the bounds.
Across all 17 zones assessed, there were two instances where the lower bound was zero (Low flow days over the low flow season for Lower and Mid Flaxman Valley). The metrics for these zones was checked against the no dams modelled data to ensure that the thresholds developed were suitable and, in both instances, the thresholds were deemed appropriate. The lower bound of zero suggests that the level and layout of dam development in these zones is having such an effect that there are periods of three or more years where there are no low flows over the low flow season. Similarly, there were two zones, Duck Ponds Creek and Upper Flaxman Valley, where the upper limit of the delay of break of season was the maximum 150 days, i.e. the season did not break. These bounds presents a problem when considering ongoing sustainability of the riverine ecosystems of the zone and will need to factored into assessment of environmental water requirement thresholds for water planning.