While searching for a way to secure a more accurate report for my tap water (aside from sending a sample to WardLabs--which I will do shortly...), I came across the following links that might be of help to those in the Madison, WI area.
allows you to plug in your street address and access the water report for the well from which your water is drawn.
allows you to browse by the various wells in the city and links to their reports.
For my address, it lists the dates for which my water is drawn from specific wells, the transition time between those wells, and much of the pertinent data needed to adjust brewing water.
However, the latest report up there is from 2010, and it is again the average of samples taken--tho at least it is an average from that one well as opposed an average taken from all the wells across the city. Not as accurate as sending a sample to the lab, but these numbers will get you closer than anything else I've found.