Minimum and Maximum Levels By Year

Max - This is the maximum lake fill level for a given year. So for instance in 1957, the lake was filled almost to the top.
Min - This is the lowest point the lake gets to for a given year. So for instance in 1994 the lake got to its lowest level of -61 feet down.

Surface Level - Last 20 Years

This is a histogram showing when the lake reaches its lowest level each year.
October is generally the low point for the year, after the summer drawdown, and before the winter rains.
When you see January, that probably means that last year's lowpoint is lower than the normal October drawdown low for the current year.

These charts are histograms of the lowest and highest levels for each year.
For instance, the highest level is usually 5 feet down or higher. In other words, most of the time the lake gets pretty close to full.
Not surprisingly, the lowest level has a much wider distribution. Almost 10% of the time it is over 60 feet down. But over 30%% of the time it never gets less than 30 feet down. (Here I summed the percentages in the last theree columns of the second chart.)