This is a graph of average water levels (annual and monthly) for the Great Lakes since 1997. (Click it if you need resizing)
While the immediate downtrend trend and projection is startling, it could be nothing more than an outlier. However, if you look from 1997, you'll see that the Midwest lakes (Superior, Michigan and Huron) all have long-term declining levels.
That's a reason to pay attention. This indicates a long-term drought has snuck up on the Midwest and Plains states. That's our breadbasket, not to put too fine a point on this.