Here's the average lake level chart for the past five years (averaged, 2013-2017) and will be used this year for all monthly reporting. Notice you can still see the impact of flooding in July and December (two little bumps in the graph) of 2015. Those flooding events left a scar on the data we'll be seeing for a few more years. For those wondering why the lake predominantly stays above the ideal level, simply remember the purpose of the lake, at least from Ameren's point of view, and that is to generate electricity. This is best accomplished when the lake is basically as full as it can be, maximising what is called "head height". In Bagnell Dam's case head height averages about 100 feet throughout the year.
The five year average levels still conform nicely to the ideal guide (grey), with largest deviation coming from the draw down period in late winter early spring. It is apparent that Ameren has no real need to strictly adhere to the lowest ideal levels for the draw down, but one of these years they're going to exercise their right and reach lower guide minimums (yellow), nearly four feet lower than the lake has seen in a long time, and shock the hell out of a lot people.
Here's the updated summary data table.