10th Anniversary of the Lake Delton Breach

The first two weeks in June 2008 featured many days with rain, and a few days with an exceptional amount of rain, across Southern Wisconsin. Between June 1st and June 14th, Madison did not record precipitation on only three days. In the same time span, Milwaukee did not record precipitation on only four days.

However, it was not the extended period of rainy weather that caused flooding problems. Those problems were primarily due to two heavy rainfall events - one on June 7th to June 8th, and one on June 12th. At many locations, over 70% of the rain fell on those three days.

Above: Rainfall totals for Wisconsin from June 5 through June 13, 2008 (left) and 2-day rainfall totals from 7 am June 7 through 7 am June 9, 2008 (right)

The heavy rainfall produced flash flooding problems across Southern Wisconsin on several days, with severe river flooding throughout the entire period. The amount of rainfall over the first half of June put Southern Wisconsin well above normal precipitation totals for that time of year. Precipitation amounts from June 1st to June 19th were over 400% of normal values across portions of Southern Wisconsin. In fact, the most anomalously high precipitation values were observed over Southern Wisconsin. The exceptional amount of rainfall in a short period of time allowed for widespread flooding issues to develop.

Ten years ago, on June 9th, 2008, a portion of Lake Delton gave way to the high water and channeled a new way into the Wisconsin River. The man-made lake drained out within two hours. Pictures shown below are during and after the Lake Delton breach.

Numerous area rivers hit record levels during a major flooding event over Southern Wisconsin in the early half of June. 25 locations reached record high levels. That represents over half of the 43 river gauges in the NWS Milwaukee/Sullivan hydrologic service area. Most of those that did not reach record levels had crests in the top 5 all time.

Also, the Cooperative Institute for Satellite Studies (CIMSS) at the University of Wisconsin Madison developed a comparison of satellite images before and after the flooding. To view these images, click here for their blog archive.

National Weather Service - Milwaukee/Sullivan