The stream flow data and graphs for 2021 are attached to this post as a ZIP file. Download and open this file to see the data. All of the graphs are in .PNG format. Raw data is also included, both as comma-separated values (CSV) files and as .hobo files.

There were no big flood events during 2021. Thunder River reached just under 4 feet in January, and never rose above 2.5 feet for the remainder of the year.

The battery in the data logger in UL2 failed around the first of September. I graphed only the first eight months of data from that logger. We have sent the logger in to the manufacturer for battery replacement.

The other loggers in the cave are approaching the end of their battery life. I will pull them on the July service trip and send them all in for battery replacement.

This year we have rainfall data from two sources. We have a rain gauge and logger mounted on the silo. This year I signed up for reports from They use radar estimates to provide rainfall data at the silo, at the natural entrance and at a location about 2 miles west of the silo. The raw data and a graph is included in the data set.

If you have any questions on how to use or interpret the data files, please let me know.

Bill Gee