Groundwater Depth Measurement    

Groundwater Depth Measurement and Heron Water-Level Meters  

Groundwater depth measurement, especially in monitoring wells is accomplished by several means.  The method used is generally determined by accuracy requirements and if relatively rapid measurements are desired.   Drillers often make an initial measurement with a "plopper" on the end of a length of twine or measuring tape.   Knots in the twine may indicate approximate depth intervals.   More accurate measurements have been collected by professionals using a chalked steel tape.   The end of the steel tape is covered by chalk and lowered until the bottom part of the tape is wet by water and the chalk changes color.   Blue "carpenter's marking chalk" is commonly used for the chalk.   The color change is from light blue to dark blue when the chalk is wet.   This method can be accurate, but it is slow.