In 1990, the U.S. Geological Survey completed a study of the hydrogeology of Huron County, Michigan. In 1993, Huron County and the USGS entered into an agreement to continue collecting water levels at selected wells throughout Huron County. As part of the agreement, the USGS provided training and instrumentation for County personnel to measure, on a quarterly basis, the depth to water below the land surface in selected wells. The program included the operation of continuous water-level recorders installed on four wells, in Bingham, Fairhaven, Grant and Lake townships (figure 1). County personnel make quarterly water-level measurements on 22 other wells (figure 1). Once each year, County personnel are accompanied by USGS personnel who provide a quality assurance/quality control check of all measurements being made.

Two of the wells with recorders are completed in the Marshall aquifer (H5r and H25Ar), one is completed in the glacio-fluvial aquifer (H2r), and one is completed in the Saginaw aquifer (H9r). Hydrographs are presented for each of the four wells with water level recorders (figures 3, 4, 6, and 8). Hydrographs of quarterly water-level measurements and range of water levels during the period October, 1988 to January, 1990 (the original project period) are shown in figures 5, 7, 9, and 10 and quarterly water levels are presented in tables 1 through 4.

Figure 2 shows the monthly-mean water-level elevation of Lake Huron, as measured at Harbor Beach and Essexville, and monthly-mean precipitation as recorded at Bad Axe, for the period October, 1988 through December, 1994. In general, Lake Huron water-level elevation were at or near record lows in late 1989, and near record highs in late 1993. Precipitation throughout the period was generally within the normal range.