Our chapter’s monitoring efforts continue, even during a global pandemic! The Willow River is one of the several local rivers and streams that we monitor for water temperature and other variables. In April of 2016, temperature loggers were installed at three locations. One is located at the USGS water-flow monitoring site roughly a quarter mile downstream from Little Falls Dam. The other two are located roughly a quarter mile upstream from the Trout Brook Road bridge, one in the Main Branch and one in the Race.
The 2018 / 2019 data retrieved from the logger in the Race showed a minimum water temperature, in January 2018, of 32.04 degrees Fahrenheit (about as close to freezing as you can get!) to a maximum water temperature, in July 2019, of 76.0 degrees Fahrenheit. From what I’ve learned, this large temperature variance doesn’t bode well for trout populations. The water is too cold in the winter and too warm in the summer. An important thing to note is that this data was collected after the Little Falls Dam was removed.
In 2014 it was determined that the Little Falls Dam needed to be replaced. By the fall of 2015, the draw-down of Little Falls Lake was complete, and the dam was removed. This allowed the river to flow freely until early 2020 when a new dam was constructed, and Little Falls Lake began to fill in. As of today, the lake is nearly 100% full. As our monitoring continues, it will be interesting to see if the dam, and the impoundment behind it, will affect the water temperatures going forward.
—John Kaplan & Kent Johnson
