Ground-water levels are basic information needed for evaluating water conditions and for basic and applied research. For these efforts, water levels are being measured statewide in wells completed in multiple aquifers. Some wells are measured for specific projects, such as the Coastal Aquifers Salinity Project and the Water Conditions program, while other wells are measured so that staff can maintain long term records of ground-water levels for evaluation of trends. Table contains summary data from wells having 100 or more water level observations.

Sinkholes are depressions in the land surface or holes in the ground caused by subsidence or collapse of surficial material into openings in soluble rock. Sinkholes usually develop in "karst" areas underlain by carbonate rocks. Karst is defined as "terrane with distinctive characteristics of relief and drainage arising primarily from a higher degree of rock solubility in natural waters than is found elsewhere" (Jennings, 1971, p.1). In addition to sinkholes, other features associated with karst are: caves, disappearing streams, and well-developed subsurface drainage systems.