So how did BRWA and its partners' stream crossing restoration projects--some over eight years old--fare in the recent flood? So far, it appears that only two of 16 sites that included installation of a culvert--to improve fish passage and/or to reduce erosion--were destroyed in the flood. These were installations near "ground zero" in the Marengo River drainage, where some of the highest rainfall totals occurred, and where some of the highest flash flood potential exists in the Bad River watershed. Over the last two weeks, BRWA staff have been receiving updates on stream crossing conditions as town and county road crews made their way in to sites that were often completely cut off by washouts.
Last Friday, with many town roads passable again, we began surveying our restoration sites to see how they stood up to the record flows. We began by visiting five sites in Lincoln and Marengo Townships. We were pleased to find them still working well, with moderate to almost no damage to the installations. Fish were even observed swimming upstream at one of the sites. Primarily, damage seems to be sand partially filling some culverts, roadbed washout around culverts, debris in stream channels, and fallen trees.
As can be seen in the images below, many stream crossings in the storm's path did not fare as well, and it will take many months to return area road/stream crossings to their pre-storm state. Careful design, especially sizing of culvert pipes to anticipate the large flows history has shown to be common in the region (and predicted to increase with climate change), correct placement in stream channels, and other considerations, result in fewer washouts. Another factor is retained forest cover--streams flowing through heavily wooded areas are less severely impacted by flow surges because of dense root systems holding stream banks in place, and the effect of vegetation slowing the flow of water over the surface as it moves down-slope toward streams.