Flood in Columbia County, Wisconsin

The river at the gage in Portage was in flood from the evening of September 24th through the morning of September 30th, and reached a record flood level of 20.66 feet during the evening of Monday, September 27th. The old record crest at Portage was 20.50 feet on 09/14/1938. The flood waters threatened to break through a century-old earthen dike in the Civil Township of Caledonia. The waters seeped through the dike, but the dike did not fail. The potential levee failures caused voluntary evacuations and road closures along the river from the Dells to Portage. As it turned out, dozens of homes in the Blackhawk Park area just southeast of Portage were cut off when water depths reached a foot on the only road into the area. The Columbia County Emergency Management Director provided the following loss estimates: $1 M for seasonal and full-time residental homes, $100,000 for patching and reinforcing part of a 14-mile earthen berm/dike, $50,000 for gravel shoulder washouts, $75,000 to a wastwater treatment plant, and $200,000 to bottomland crops. It was postulated that damage was limited due to the fact that the flood waters rose slowly which reduced the erosional power of water. The EM Director also noted that the Wisconsin River levels in Portage were about a foot higher than that experienced in the Great Flood of 1993, while at Wisconsin Dells the 2010 level was about a foot lower than that experienced in 1993.

Even though heavy rains didn't fall in the surrounding area, record river levels occurred on the Wisconsin River near Portage. A potent, early-fall, storm brought waves of heavy rain to western and central Wisconsin, well upstream from Portage, beginning late on Wednesday, September 22nd and continuing into early Friday, September 24th. Two-day rainfall totals of 4 to 8 inches across the Wisconsin River basin over those parts of Wisconsin resulted in flooding in the river basin from Sauk County near the Wisconsin Dells downstream through Columbia County.