Northern Research and Demonstration Farm
One of the reasons the Northern Research Farm south of Kanawha was purchased was to study tile drainage systems. In order to measure the depth to the water table, an open-ended pipe was installed in the ground near a four-foot-deep tile line. Since 1963, the distance to water table for selected dates has been recorded.
Iowa State University
Rueber, David, "Distance to Water Table" (2006). Iowa State Research Farm Progress Reports. 1115.