This is a five year lake level summary created by averaging hourly levels from 2011 to 2015. In general, lake levels have adhered to the guide curve, with the major deviation from February through April.
The effect of flooding in 2015 can be seen as sharp peaks in July and December. At this point it is important to note that Ameren continues operate the dam at the high end of the curve guide. This is presumably due to the desire to have maximum head height (the difference between the lake level and the Osage River level which is the key parameter to electric generating capacity).
Below is the table summary for the past six years with the latest five years and averages on the right, and the oldest on the left.
With six years of data we can begin some interesting trend graphs. Like this one, showing the average lake level for the entire year for each year. The small blue line is a two-year moving average trendline.
While we are all aware of the limit to which the dam can hold water, it is the year round total average we see trending up, and may continue to do so in the coming years as more water is held during normally low months.
The next graph is for the Osage River, again with two year trendline, where we can see the average level behaving a bit more erratically, although it too has a small upward trend building.
Finally a graph of the average discharge from Bagnell Dam with a two year trendline.