In addition to Rich’s posting on Facebook and in News & Information, here is the August 26, 2016, hydrograph of the South Branch Root River flow at Carimona, just 6 miles upriver from the NTC at Preston, Minnesota. While the flow is down to just 610 cfs from its peak at over 2700 cfs, the astonishing feature of this graph is the rapidity with which the river flow increased from its leisurely 200 cfs to more than 10 times that flow in less than 24 hours. This is the very definition of a flash flood!
At Lanesboro, the river is still flowing at 886 cfs, and the hydrograph below shows a flash flood of urgency comparable to that upstream at the Carimona gauging station.
Comparison of these hydrographs allows us to see how much the Willow Creek and Camp Creek watersheds contribute to the South Branch Root River flow as these drainages are included in the Lanesboro hydrograph, but not the Carimona hydrograph. The green vertical bars representing precipitation events also show an example in this hydrograph of a storm recorded in Lanesboro on August 15, but not influencing the river flow arriving at the Lanesboro stream gauge.
The mega-rainfall event over the night of August 23-24, 2016, was yet another example of changes wrought by recent climate change. Although we did not experience the kind of flooding described in our blog post “Louisiana Blues” it is clear that trout fishing in southeast Minnesota has been greatly pock-marked by this phenomenon during the summer of 2016. Even without any further rainfall, the South Branch Root River will be virtually unfishable for the rest of August. Other small tributaries in the region, such as Trout Run, Gribben Creek and tributaries of the Whitewater River will likely remain fishable through the summer and fall, but it would be prudent to call ahead or check stream condition websites to ascertain conditions before travelling to the area.