Flooding

Mendota is at elevation 850.57, this is up from an elevation of 850.11 last week. The Summer Maximum by Wisconsin Department of Natural Resources order is 850.10. (So, we are approximately 6 inches over Summer Max). The 100-year elevation is 852.8 but we can only currently effectively rise to 852.0.

Monona is at 846.02 up from 845.86 last week – summer MAX by WDNR order is 845.20 (so we are 10” over). The 100 year is 847.7.

The problem elevations on the isthmus are at about elevation 848.5 to 849.00. As Monona rises nearer to 847.00 our drainage system in the isthmus area will become less effective.

Risk Assessment

We experience no significant additional flood risk due to the current lake levels, but we are approaching lake levels on Monona that will diminish storm system efficacy. The levels will not cause back-ups, rather reduce the rate at which low areas on the Isthmus drain during an intense event.

We are forecast to get scattered rain on Saturday (.25 inches) followed by a reasonably extended period of dry weather (finally!).

If you recall, typically 1 inch of rain in the Mendota watershed gets you a 3 inches rise in the elevation of Lake Mendota.