October 10, 2019
Welcome Back to the NTC’s The Voice of the Driftless.
Jeffrey S. Broberg
The Late Catch and Release Trout Season will end Tuesday Oct 15 and all the trout streams will be closed to angling except in the five cites and three State Parks that have continuous seasons. The good news is that despite all the rain we can still find good fishing in headwaters, 1st Order streams and the few spots that missed the recent rains. All is well unless we get more rain.
No matter where you go the streams are very high, this is the highest base flow I can remember seeing at this time of year. When I look at the stream flow gauges for the last 30 days in the Root River the flows are 5 times higher than in 2017, and more than twice as high as 2018, another record setting year for local precipitation.
This week: To me the most interesting NOAA map was the 30 day “departure from normal precipitation” this shows how much more rain than normal we have had in the last 30 days. WOW. Half of Fillmore County, the headwaters of the Root River have had 11 or more inches of rain…8 inches more rain than normal for a period that usually get just over 3 inches of rain!
For the best fishing look to the headwater streams on the east.
Lesson on stream flow
River and stream gauges measure the stage or elevation of the water and calculate the flow based on the speed of the water and the cross section of the stream. We report his data in cfs: cubic feet per second. This engineering measure is often converted to different units of measure to get the point across.
A cubic foot of water is 7.48 gallon and weights 62.42 pounds. We can calculate the number of gallons per hour, or calculate how many acre-feet of water per day (one acre, one foot deep per day), and if we want we can even calculate the weight and the force of the water at the gauge.
Looking at the Middle Branch Root River (MBRR) at Fillmore and the South Branch Root River (SBRR) at Carimona stream gauges and reviewing the difference in flow from 2017, a “normal” year for rainfall, to 2019, a record year for rainfall there is a five-fold increase in base flow this year.
If you think about this in acre feet you can see…this year the trout have a lot more water! The streams are full of water and the trout have lots more space to swim in the streams. For just the MBRR we have flows of 793 acre feet per day more in 2019 than we had in 2017.
Consider that a square mile has an area of 640 acres; and 640 acre feet equals a mile covered a foot deep in water. This means that this October we are discharging way more water than past years. On the MBRR the increase in flow is equilivant of 1.23 square miles of water that is a foot-deep water – every day!