As I look out on the lake every morning I'm still a little surprised as to how low the level remains for for this time of year. By my record keeping, the five year moving average lake level for this date (indicated in orange in the chart), March 28th is 655.36 feet, more than a foot higher than it is today. So what gives?
Obviously the threat of flooding is on Ameren's mind and from the chart below, which is an incomplete graph for this month, they are adjusting flow (in green) through the dam in direct response to rising lake levels. It's a clear attempt to keep lake levels where they are in what appears to be a purely reactionary response to the rains as they come. Ongoing repairs to the dam may be the prime mover here since there's really no other reason to keep levels this low now.