Since the recent rains started on Monday, July 6, we have recorded 3.71 inches of rain and that puts the lake level at 51 3/4″. Looking at our familiar level history chart at Our Works > Water Level Reporting we see it is extremely high.
As for how we know the amount of rain received so accurately, have a look at the various unusual objects off the east side of the Bates’ dock. This is very accurate (and expensive) DNR owned equipment that includes one downloadable recorder and three Bluetooth enabled transmitters. It is all a follow-on to the Piezometer study done on the lake during the summer of 2013. Read about that near the bottom of Our Work > Water Level Recording. This was a study that placed piezometers at 53 sites around the lake and measured pressure differences between just above the bottom and just below the bottom. Any difference in pressure meant that water was flowing through the bottom in one direction or the other. Read that analysis and you’ll see that we are losing much more water than what we gain and you’ll also learn the various frontages where inflows and outflows are most pronounced.
This current study uses an “Evaporation Pan” which is a large bin of water (about 18″ by 30″ by 20″ deep) supported by the large block of Styrofoam surrounded by barbed wire. That container has two sensors at its bottom sensing the depth of water in the “pan” and the temperature of that water. The only water that gets into it is rainfall and the only water that leaves it is by evaporation which is affected by water temperature and wind, which is also recorded. Those sensors broadcast their findings every thirty minutes to any nearby iPhone. Oh, and the barbed wire is to dissuade otters, muskrats, and loons from using the floating Styrofoam as a nest, which they have been inclined to do!
Then there is a rain gauge on the vertical steel post attached to our dock. It is a “seesaw rocker” type device that measures rainfall to one ten thousandth of a meter! Then there is a water level sensor within the large piece of white PVC which records water level in the lake to the same accuracy. All these sensors transmit their readings constantly.
The idea here is that the water level in the lake should vary according to only rainfall and evaporation as we are a “seepage” lake that has no inflows or outflows. If that calculation and a measurement of the actual level change is anything other than it should be it can only be due to water flow through the bottom. I send sensor readings to the DNR every Sunday and they are making these calculations. At the end of the summer they will reveal just how much water we are losing everyday through the bottom of the lake.
- Walt Bates