Four vertical geophysical probes were constructed primarily to measure the subsurface resistivity through the vadose zone and into the aquifer. These probes were installed at increasing distances from a pond in Van Buren County, Michigan, in an inhomogeneous soil. Monitoring of these probes began in December, 2005, and has been continuous through September, 2007, providing nearly two years of uninterrupted data collection. Pole-pole resistivity measurements with an a-spacing of 5 centimeters are recorded every four hours during normal conditions and at 3-minute intervals during and for two hours following infiltration events. Long term results illustrate the importance of temperature, saturation state, and seasonal effects (related to the changing ionic load of infiltrating water) upon resistivity in the shallow subsurface. These factors can create a change in subsurface resistivity of over one hundred percent in the vadose zone and nearly forty percent within the upper saturated zone. The measurements and analysis presented suggest caution for the use and interpretation of time-lapse, shallow subsurface resistivity measurements to monitor changes at sites of interest.