Home Biscayne aquifer Hydrologic system Water quality Ground-water withdrawal Vulnerability of Biscayne aquifer Future problems of potable supplies Other drinking water sources Summary & References PDF Version

Future problems affecting the potable water supplies of the Biscayne aquifer are related to continued growth of population and industry. Continued growth will result in increased demands for potable water and increased generation of waste water and solid waste. Until such time that costs of desalination become competitive with costs of obtaining freshwater from the aquifer, agencies will continue to depend upon the Biscayne aquifer as the prime source. The current and future policies of the public utilities generally involve unifying or incorporating the many small individual water-supply and waste-water systems into larger regional systems for more efficient operation and more uniform treatment.

A prime consideration in providing potable water supplies for future demands will be saltwater intrusion into the aquifer. The existing major municipal well fields will continue operation, although some may be at reduced pumping rates because of the potential for saltwater intrusion. Additional supplies for satisfying future demands will be from well fields inland from those operating in 1978, greater distances from the threat of saltwater intrusion.

Future water needs will rely heavily upon the practices, operations, and water-use plans of the SFWMD. One recommendation of the District is to locate new supply wells further from major canals. This will maximize withdrawal of ground-water from aquifer storage, minimize reliance on diversion from canals and tend to insure that adequate quantities flow through the canals to the coast to retard saltwater intrusion.

However, pumping will eventually divert canal water into the aquifer and to the pumping wells. The quality of the ground water withdrawn will then resemble the chemical characteristics of the canal water. As pumping rates increase, greater reliance will be on inflow from the canals and the water-conservation areas. The main canals that transect Broward and north Dade Counties obtain water from the water conservation areas that is high in organic content. It would be expected that organic-rich water would be diverted toward the wells, altering the chemical quality of the ground water. The sand and limestone of the aquifer would filter some of the organic compounds.

Another problem related to reliance on the water conservation areas and Lake Okeechobee for replenishment during dry seasons is the gradual degradation of the replenishing waters. The quality of the interior waters may become degraded because of backpumping of surplus water from the agricultural areas south of Lake Okeechobee and because of the inferior shallow ground water southeast of Lake Okeechobee as shown by Parker and others, (1955, fig. 211). The surplus water backpumped into Lake Okeechobee or pumped into the conservation areas contains nutrients and other chemicals from farming activities. Joyner (1971, p, 86) has indicated that the early eutrophic condition of Lake Okeechobee was due in part to backpumping. Because. The water in the lake and the conservation areas is channeled through canals to the southeast to replenish the Biscayne aquifer during dry seasons, the potential for degrading ground water is apparent.

One of the water-management schemes proposed by the SFWMD is to backpump part of the surplus storm water in the urban and suburban areas of southeast Florida to the water conservation areas, thus, reducing the discharge of freshwater to the ocean. The total daily flow to the ocean of the major canals of the lower east coast ranges from 1,000 ft³/s (650 Mgal/d) during a dry year to more than 6,800 ft³/s (4,400 Mgal/d) during a wet year (McPherson and others, 1976, p. 55). The average flow is 2,550 ft³/s (1,650 Mgal/d) during an average rainfall year. These discharges are presently (1978) considered necessary by the District to prevent flooding in developed areas. The water to be backpumped probably will contain some toxic substances and nutrients from the urban and agricultural areas, which in sufficient quantities, could further degrade the water stored in the conservation areas. Some of the nutrients would be utilized by the vegetation in the conservation areas and some toxic substances possibly would be adsorbed by the organic soils.

During the past decade urbanization has been spreading inland toward the water conservation areas, into undeveloped land, and land already devoted to farming. Future growth probably will maintain that pattern because the interior land is less costly than land near the coast. The inland areas are of low elevation and are subject to periodic flooding. As indicated, the interior parts and the water-conservation areas are where ground-water flow originates during the dry seasons. If those areas were to urbanize, such contaminants as might be associated with urbanization could degrade the ground water.

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