feet, most of them being between 200 and 300 feet. Samples were collected of the rock cuttings and of the water encountered in the test wells, and pumping tests made at many levels as the wells were being drilled. In addition to these test wells, numerous shallow, observation wells were installed for periodic water-level measurements. Twenty-one automatic water-level recorders were placed on selected wells to determine the fluctuations of the water table.
Studies were made along several stretches of the major drainage
canals to determine the amounts of gain or loss of the ground water. Several studies were made of the altitude and movement of the ground water in relation to the stage of the canals in an extensive area west of Hialeah and Miami Springs, during low, average and high water conditions, to permit effective evaluation of water-control measures to protect the present well field. These studies also have a direct bearing upon the future development of additional supplies in the area. Four intensive studies were made in the Silver Bluff area of Miami to determine the conditions governing salt-water encroachment at depth in the water-bearing formation. Thousands of samples of water from representative wells were collected, and analyzed to determine
the quality of water. In a study of the problem of salt-water encroachment, samples of water from Biscayne Bay were also analyzed. Artificial mixtures of normal ground water with sea water were made in various proportions and comparisons were made between these and samples of salt-contaminated ground water. Eighteen rain gages and four evaporation stations were installed to assist in determinations of the supply of water from rainfall and of losses that are due to transpiration and evaporation.
Most of this work was done. in. Dade County, in the area centering