PROTECTION OF GROUND WATER SUPPLIES IN THE MIAMI AREA
The protection of ground water supplies in the Miami area embraces two problems: one is the protection of the present well field from salt water encroachment by way of the Miami Canal and the other is the protection of both the present well field and all other sources of ground water supply from salt water encroachment at depth in the aquifer. The characteristics of both movements are described in an earlier section of this report. The successful solution of these problems is through control of ground water levels by means of regulation of the drainage canals.
Protection from Salt Water Encroachment by Way of the Miami Canal.-The more immediate problem is the protection of the present well field from sea water which passes upstream in the Miami Canal during periods when the fresh water flows are insufficient to hold the sea water back. This problem might be attacked in three ways. First, the discharge in the unregulated lower reaches of the Miami Canal might be augmented so that the larger discharges obtained would hold sea water sufficiently far downstream, without the use of dams, to prevent its encroachment into the well field. Second, a system of barriers might be maintained in the Miami Canal to prevent wastage of fresh water and the incursion of salt water far up the Canal and thus achieve a similar effect. Third, canal flow regulation and/or augmentation might be combined with the operation of a salt water barrier.
The first method does not appear practcable because of the difficulties of providing the relatively high rates of flow needed during periods of drought. A minimum discharge of about 250 million gallons per day should be maintained at the Miami water plant for effective sea water flushing