In Part One of the Water Year series, we learned that the median is a better means of representing typical conditions on the Kern than the mean. The mean is improperly skewed by outlier years, as shown by this chart, which groups the water years in hundred-thousands of Acre-Feet:
As can be seen, the data bunches up on the left; a majority of the last 50 years see below 600kAF of inflow at our reservoir. The outlier years to the right skew the mean so that just short of two-thirds of the years fall below the mean. The mean is accordingly not a fair representation of this statistical distribution. The median is a more appropriate representative: half the years fall above it, and half below.
In this next graph, KRB took the daly data available below Fairview Dam (both in the riverbed and in the KR3 diversion canal), summed them up to establish the total inflow at Fairview, and then aggregated those figures by year, to establish an annual average flow. From these figures, we can see that although the mean flow is 766 cfs, the median is only 531 cfs; again, half the years fall above the median, and half below.
Here is a chart of the last 30 years’ data:
You can find our full analysis of water years on the Kern in our comments to FERC on KR3 at pages 23-30 & 48-69.