National Academy of Sciences Advisory Committee on Research in the National Parks The Robbins Report

THE WATER SUPPLY PROBLEM OF THE EVERGLADES NATIONAL PARK*

Introductory Statement

Southern Florida is a low-lying peninsula of prairie and swamp. Only a small portion of the area stands at an elevation above 25 feet, and the extreme southern part lies almost at sea level. Prior to 1900 it was almost uninhabited except by the Seminole Indians. That part known as the Everglades is the eastern half of the peninsula south of Lake Okeechobee. The Everglades Park, which was not established until 1947, lies south of latitude 25 45' (which is about the latitude of Miami) and does not include the coastal strip about 25 miles wide, extending from Miami south to Key Largo. (see Plate I)

Prior to the drainage of the northern Everglades, the whole area was a vast solitude of saw grass and water with "hammocks" of trees, various slough areas and higher ridges of pine land. Along the south and west coasts were extensive forests of mangroves. The rainfall is heavy, averaging about 57 inches per year, but the rains come almost entirely in the summer months, leaving the winter and spring very dry. There is a great variation in the amount of annual precipitation.

Prior to the digging of drainage ditches, the area now occupied by the Park, received a large amount of water flowing slowly down from the north, and during the summer most of the area was covered with water. The Kissimmee River which flows southward from Central Florida, drains a large area south of Orlando, and discharges into Lake Okeechobee. In its natural state, the lake had no well-defined outlet. Before the digging of the canals, the lake would fill to overflowing in the summer months and the water would flow over its banks, and spill slowly through the swampy areas and sloughs, moving generally outward to the tip of the Peninsula.

Hurricanes caused heavy flooding. The hurricane of 1928 during which there was a wind velocity of 150 miles per hour, caused a "tidal wave" on the lake 13 feet high, which flowed over the land to the south and drowned hundreds of people. Following this catastrophe, the Federal Government undertook an extensive flood control project to drain away the flood waters from the rich agricultural land south of the lake.

However beneficial the drainage was to the agricultural community, there were many side effects. Gerald Parker of the U.S. Geological Survey wrote: [1]

"It is doubtful that the drainage enthusiasts ever envisioned that, among other results of their operations, they would induce or cause:

1. Shrinkage, compaction, oxidation, burning and general subsidence of the organic soils . . . as much as 5 feet over extensive cultivated areas.
2. Development of wide shallow "subsidence valleys" along each drainage canal.
3. Increase frost damage, which formerly had been held in check in the muck and peat soils by the ever present water which gave off heat as it froze. (Parker wrote this before the winter of 1962-3 when the loss by freezing of vegetable crops was enormous. Note by author of this paper.)
4. Reduce the original capacity of the canals, thus contributing to flooding.
5. Cessation of the processes that had built up the muck and peat in the first place.
6. Changed ecologic conditions seriously affecting wildlife of the drained areas, resulting in species migration or near extinction.

Water problems have become of prime importance. Whereas we in this area were first concerned only with getting rid of water, or practicing flood control, we now are greatly concerned (with effects caused by inadequacy of water)."

It is not possible to state accurately how much water formerly flowed into and through the area now occupied by the Park. A publication dated May 22, 1950, by the Flood Control District, as quoted by Lamar Johnson of Lake Worth in a report which he wrote in July, 1958, entitled, "A Survey of the Water Resources of Everglades National Park," page 7, is as follows:

"The estimated discharge along the 40-mile front at the present location of Tamiami Trail during the pre-drainage period, was:

"Average rainfall year - 2,315,000 acre feet
Dry rainfall year - Negligible
Wet rainfall year - 10,744,000 acre feet"

An acre foot is approximately 325,800 gallons.

These figures indicate not only the tremendous amount of water which flowed through that area in wet years, but also testify to the great fluctuation in quantities from wet to dry years.

A program of stream flow measurement was begun in 1940 by the U.S. Geological Survey. The average flow through the 43 mile reach of the Tamiami Trail for the 17 years, 1941-1957, was 473,200 acre feet, with a minimum discharge of 80,120 acre feet and a maximum of 1,437,000 acre feet. Thus the average flow was only 20% of the "pre-drainage period" and the maximum was only 15% of the original maximum. Further, in not one year of the seventeen years, did the maximum flow even approach the average of the pre-drainage period. It is that fact that is most discouraging in the study of the water situation of south Florida.

The resulting lowering of the water table within the area of the Park, is indicated most convincingly by the fact that the vista of the vast sea of saw grass is now broken by the presence of abundant willows which have sprung up here and there. More serious is the diminishing number of colorful sea birds, which come into rookeries in the sloughs within the Park area during the spring months, feeding on young fish which had been spawned during the previous period of high water. Whereas these birds used to come into the Park area to raise their young by the hundreds of thousands, now the numbers are in the thousands, since there is not enough food available for the larger number.

If the Everglades had a principal reason for having been made a National Park it was to protect these birds which thousands of tourists and bird watchers were coming to see and admire every year.

Can the supply of water for the Everglades Park be increased to anything like the quantity that formerly flowed into the area? This is the burden of this discussion. It must be remembered that the Park was not established until 1947, by which time the damage done by the drainage of the northern Everglades was well under way.

Greater Miami and Its Water Supply

East and northeast of the Everglades Park is a huge municipal complex within Dade County, called "Greater Miami", which includes the city of Miami itself, Miami Beach, Hialeah, Coral Gables, and numerous smaller communities. Fort Lauderdale is north in Broward County, and Palm Beach still further north in Palm Beach County. The present population of Dade County is estimated at about 1¼ million, but the area is one of the fastest growing in the country. The population has been doubled every 10 years, and if this rate continues, the population will reach 2 million by 1970, and 4 million by 1980. One shudders at the thought that 1980 is only 16 years away, less than the time since the end of World War II, which to those who were active in it, seems a very short time ago. Four million people take up a lot of room. One thinks of Los Angeles or Chicago each with 500 square miles of fairly densely built-up city. When that many people have come to live in Greater Miami, there will hardly be an open field or wood lot in the eastern half of Dade County. Most of the residential area of Greater Miami is built on the "Atlantic Ridge", (see Plate II) a coastal sand strip of Pleistocene deposition. Outside of "downtown" Miami most of the people live in individual homes surrounded by lawns and the present planners seem to believe that this condition will continue. It must be remembered, however, that even in "suburbia", streets, driveways, and sidewalks take up one third of the available area, and community service facilities such as shopping centers with their huge parking areas bring the paved-over surface to about half of the total.

Greater Miami is blessed by having available to it one of the largest sources of fresh water of any city in the United States, except those cities located along the shores of the Great Lakes. All of this water comes from wells driven into a formation immediately underlying the Atlantic Ridge called the Biscayne aquifer. This aquifer is kept supplied now by water from rains so that there is now no conflict of interest between the water needs of the great municipal area, and the needs of the Everglades Park. Whether this happy situation can continue will be analyzed on subsequent pages.

The Biscayne aquifer, named after Biscayne Bay (Plate III) extends along the Eastern coast from southern Dade County north into coastal Palm Beach County, as a wedge-shaped underground reservoir having the thin edge to the west. It underlies the Everglades as far north as northern Broward County, but is thin under the Park itself.

Gerald Parker has described the Biscayne aquifer as follows: [2]

"The Biscayne aquifer is a hydrologic unit of water-bearing rocks ranging in age from upper Miocene through Pleistocene. The important members are the Miami oolite and the Fort Thompson formation, both of which are very porous, and permit very free movement of water."

"The aquifer is at once one of the area's greatest natural resources and one of its most difficult assets to protect. It rests on a gently sloping impermeable floor of clay, silt and dense marl. No saline intrusion can work its way upward through these materials, but the Biscayne aquifer is leaky above and on all sides. Rain finds ready access to the aquifer, and with Miami's 60 inches of rain fall per year, the aquifer is kept nearly full much of the time. The aquifer is open to the ocean on its seaward side, and the fresh water of the aquifer discharges into salty bay and ocean water."

The drainage canals have cut through the upper part of the aquifer, thus bleeding off some of its reserves, and these canals connecting with the sea, have permitted salt water to come inland during high tide, and much damage from this salt water intrusion has occurred, so that many wells have had to be abandoned. The danger has been recognized, and tidal traps have been installed in the canals near their points of discharge into the Bay or ocean. These traps let fresh water flow out at low tide, but close automatically against the rising tide, like a trap door.

Tremendous quantities of water are stored in the Biscayne aquifer, but most of this is "dead storage", that is, so much of it lies below sea level, that the water table cannot be drawn down by heavy pumping without inviting salt water to flow in from the sea.

Parker has estimated that there is an annual net gain of new water from recharge by rain of .15 to .45 billion gallons per year in each square mile of surface. Using a median figure of .3 billion gallons per year per square mile of area, one may make an approximation of the "safe yield" that can be pumped from the aquifer, without depleting the reserve.

The area in Dade County within which wells can be drilled for water to supply existing or future populated areas is a zone roughly 20 miles east-west by 40 miles north-south, giving an area of 800 square miles for recharge. Thus there may be a potential supply of water from the Biscayne aquifer of 240 billion gallons per year which may be pumped, without depleting the reserves, or causing excessive draw down which will invite salt water invasion.

When the population reaches four million, and a large part of that area is taken up by "suburbia" about half of that suburban area will be paved. This will reduce the recharge, since water that falls on streets, sidewalks and the enormous parking lots around shopping centers flows down sewers. It can be hoped that by that time storm sewers will have been built in the suburban area, and the discharge collected and returned to the ground through recharge wells, Ranney-type collectors, or ponds established in areas not yet then completely built-up.

It is pertinent and important at this point to introduce the reader to the Conservation Areas which have been established (Plate I). These have been a most wise development. There are three of these, No. 1, No. 2 and No. 3, graded at elevations so that water from No. 1 will flow into No. 2 and from 2 into 3. The Conservation Areas are bounded by levees, the construction of which is presently almost complete. The purpose of the Conservation areas is to intercept flood water running out of the canals before it is lost out to sea, and to store it so that the Biscayne aquifer will be kept recharged.

If the recharge into the aquifer used by the present well fields is reduced, some wells may be drilled further west in order to have the benefit of the recharge from the water in the Conservation Areas. A western location for these wells, further away from the danger of salt water infiltration is advantageous. There the water level can be lowered by more intensive pumping, and more water will run into the ground from the conservation areas. That was the purpose of these conservation areas, and the recharge into these western wells will supply the water for the urban area.

At the present location of the wells, little or no recharge could result from these conservation areas, since the distance is too far to give any effective gradient. Hence any water standing on the Conservation area 3 will seep gradually south into the Park. When the wells are moved west into area 3-B, or area 3 itself, the recharge will tend to exhaust the standing water in Conservation area 3, (except in flood years) and there will be less water to move down into the Park. That is when the flow into the Park will indeed by greatly reduced.

If there are any alternatives, now is the time to consider them as advance planning.

At the present time the average community in the United States uses about 150 gallons of water per day per person. This quantity includes industrial requirements, if any; water to sprinkle lawns and gardens, to fill swimming pools, to cool the compressors used for air conditioning, sanitary water to flush toilets, and, finally, for such domestic use as bathing, cooking, and for thirst quenching. Biscayne aquifer is adequate for the requirements of over 4 million people (based on present requirements). Hence, so far as the inhabitants of Greater Miami are concerned, they will not have to turn else where for water until well into the 1980's. They are thus much better off than most other communities in the United States.

Generally, the wells in the Biscayne aquifer are easily developed. They are either of open-hole, rock wall construction, or they are finished with a sand point. Most of the wells are of the former type and are from 1¼ to 18 inches in diameter. A common well in the area is 6 inches in diameter and from 50 to 65 feet deep, with 3 to 10 feet of open hole in highly permeable sandy limestone below the bottom of the casing. The yield ranges from 1,000 to 1,500 gpm, with a draw down during pumping of less than 4 feet; recovery occurs almost immediately after pumping stops. Most municipalities in the Greater Miami area are now served by the supply of the city of Miami, most of which is pumped from a well field in the Miami Springs-Hialeah area. Currently, about 60 million gallons per day are pumped. Some of the adjacent municipalities, such as Opa Locka, North Miami and North Miami Beach, have their own public water supplies.

The Miami area makes considerable use of wells for fire-fighting purposes. In order to obtain large quantities of water for this purpose, wells have been drilled at strategic locations over most of the settled area. Each well will supply a fire-fighting "pumper" with at least 1,000 gpm. Probably no other large city in the country has such facilities.

The possibility of developing well water to supplement the natural flow into the Everglades Park is good. Parker and Associates state in Water Supply paper 1255, p 178:

"In the Everglades National Park area, the Biscayne aquifer is composed of rocks of the Miami oolite and Fort Thompson formation. These rocks are riddled with solution holes and are highly permeable . . . the aquifer is not thick however; at the Tamiami Trail it is only about 20 feet thick . . . the quality of the water several miles inland from the Bay of Florida or the Gulf of Mexico is good, being a typical calcium bicarbonate type water . . . excellent wells for potable water could be developed and would be capable of yielding as much as several thousand gallons per minute . . . it would be essential to stay as far away from salt water sources as possible to prevent contamination by encroachment of sea water."

The flooding of Conservation Area No. 3 to supply recharge to the Biscayne aquifer for the benefit of the Greater Miami area will also benefit wells that might be drilled on the Park side of the Tamiami Trail. The modest thickness of the aquifer limits the draw down that can be operated in each well, but the cone of influence around each will therefore not be too great, and a number of wells can be drilled. Greater Miami will obviously put its wells either in the 3-B area, or lined up along Levee 67, in order to keep as short a pipe line distance to its mains as is possible. The Park can tap the aquifer all along the Tamiami Trail, a distance of 12 miles and along the west side, south of Tamiami Trail. It is not unreasonable to expect that 25 to 40 wells might be put into operation along these lines. These wells might yield as much as 250 acre feet per day. They could be operated during the dry season of the spring months, contributing 25,000 acre feet into the Rookeries at the very time it is needed most.

During wet years, when ample water is flowing down from the heavily flooded area of Conservation Area No. 3, and water is standing all over the north part of the Park, these wells should not be needed, but in dry years, they would be a "Godsend".

Salt Water Infiltration

It has been mentioned that salt water encroachment into the Biscayne aquifer is a constant threat and has occurred and caused some wells to be abandoned. Fortunately the danger has been appreciated, and remedial measures have been taken. The subject is discussed at length in Florida Information Circular No. 9, by Howard Klein, Tallahassee, 1957. Figure I of that report shows six maps delineating the progressive salt water encroachment for the period 1904 - 1953.

The only serious threat in the Miami area now is from careless over pumping. The water supplies in the Biscayne aquifer are like money in the bank. In times of need, it is a natural impulse to overdraw. If the ground water level is lowered below sea level near the ocean shore, or near the salt marshes, salt water will come in, and once in an aquifer, the salt is difficult to flush out. During times of high water levels, salty wells can be pumped to waste, with the hope that additional infiltration of fresh water can be induced,

In the Park area, salt water encroachment has taken place. In a well 13 miles southwest of Royal Palm State Park, the chloride content is high. Since most of the extreme southern part of the Park is at or below sea level, the surface water is salty, and is inhabited by marine species.

Florida Bay is an anomaly, since the water in it is saltier than in the open ocean, due to inadequate circulation through the narrow connections at its opposite ends. A serious effect was noted at Flamingo during the visit of the Committee in January. There a canal had been dug to give motor boats access to Coot Bay and on through to Whitewater Bay. This canal is allowing the super-salty water of Florida Bay to pass into the under-salty water of Coot Bay. The harm in that situation is that baby shrimp are hatched in the brackish waters of Coot Bay, and are killed if the water becomes super-salty. The canal is so big that simple tidal traps will not serve. It will require regular locks which will have to be opened and closed for the benefit of the motor boats.

Sewage Disposal

Incredible as it may seem, a large part of Greater Miami is not served by sewers, but rather each home or group has septic tanks which have been emplaced in the top of the very permeable Biscayne aquifer. That such a practice has not led to repeated epidemics is surprising, and must be a proof of the efficacy of chlorine. The built-up parts of the cities of Miami and Miami Beach are served by a sewage system, with a treatment plant on Virginia Key, which is the next island south of the one on which Miami Beach is located. The effluent is pumped out to sea. Whether any of it gets back on the beach is not reported in the travel brochures.

Obviously septic tanks will not be adequate for very long, considering the steep rate of growth of the population. Collection and treatment of all sewage except in the most outlying communities must be installed.

Dade County has taken a very wise decision and has passed a law stating that by early 1965, no "hard" detergents can be used or sold in the county. This vote resulted from difficulties with foaming in sewerage lines and in septic tanks. This elimination of hard detergents makes possible the use here proposed for piping the effluents from primary sewage settling tanks which eliminate solids, both organic and inorganic, out to oxidation ponds or lagoons and from them decant the purified water into the sloughs in the Park. Hard detergents are poisonous to fish, even in very minor concentrations. The new soft detergents are not.

Several chemical companies are known to have the soft alkylate detergents ready. These companies include Monsanto Chemical Company, Allied Chemical and Dye Corp., Union Carbide Corp., California Chemical Company (Standard Oil of Calif.), Continental Oil Company, and Ejay Chemical Company (Standard Oil of N.J.). The rapid degradation of the soft detergents, which are called linear alkylate sulfonates, by bacterial action has been described in a recent article in "Chemical and Engineering News" for June 24th, 1963, p. 37.

On the assumption that within a very few years, Greater Miami will have to collect and treat all of its sewage, it is pertinent to estimate how much effluent would be obtained as water which can subsequently be purified by oxidation in ponds or lagoons. Ignoring the run-off from storm sewers, which run-off should be essentially clean water and which as above suggested should be collected separately and put back into the Biscayne aquifer through recharge wells, Ranney collectors or ponds in new city parks, the amount of sanitary sewage effluent can be estimated.

It has been stated that the water use per person per day in the typical American community is 150 gallons. How much of this will come out as the fluid effluent from the primary stage in a sewage treatment plant involving essentially only sedimentation or settling out of the solids?

It is fortunate that Miami does not now have, and probably never will have large chemical plants which have chemical wastes to discharge which can neither be neutralized nor sufficiently diluted and which would kill the bacteria which cause purification in oxidation ponds, and which chemicals could later kill fish which might be planted in these ponds. Hence the effluent will be reasonably free from chemical wastes.

In a climate such as that of southern Florida, where a substantial amount of water used is for lawn sprinkling, and for cooling the compressors in air conditioning, it can be assumed arbitrarily that of the 150 gallons of water used per day per person, 25 gallons of this will never reach a sewer, but rather will be evaporated or will soak into the ground. According to Fair, Geyer and Norris [3] the volume of wet sludge from the primary sedimentation of raw sewage has a volume of 37.8 cu. ft. per 1,000 persons in the community, and the sludge contains 95% water. This is only .0378 cu. ft. per person, and hence the water loss with the sludge is insignificant, most of it is separated as almost clear effluent. However, to be conservative, and for easy calculations, it is assumed that the effluent will amount to 100 gallons per day, per person.

Oxidation ponds or lagoons are now an accepted method of treatment of effluent water. The oxidation pond is an artificial lake into which this effluent flows. The pond is shallow and absorbs air at the surface so that aerobic bacteria thrive and reduce the B.O.D. (biological oxygen demand). According to Steel [4] there are 188 communities in Texas served by oxidation ponds, and many others in other southwestern States. Although these ponds are used in the north, they are not effective during the winter when the ponds are frozen over.

Steel estimates that a pond should have an area of one acre per 500 persons contributing to the sewage. The retention period is about 25 days, or, for convenience in calculations, a month. Assuming a population of 1,000,000 persons, contributing 100 million gallons per day of effluent, or 3 billion gallons per month, this is equivalent to 9,200 acre feet. If the pond has an effective depth of 3 feet, the pond to give a month's retention time for the effluent from the treatment of the sewage produced by 1,000,000 persons will have an area of a little over 3,000 acres, or 4½ square miles. This is an insignificant requirement in the Southwest Dade Area, for example, which contains about 235 sq. miles.

Steel says that depths in practice vary from 2.5 to 4 feet. Lesser depths encourage emergent aquatic vegetation which fosters mosquito breeding, and interferes with convection currents and movements in the water, thus reducing oxygen intake. The soil in the bottom should be relatively impervious to avoid rapid seepage. He states further that a number of studies indicate the feasibility of returning treated sewages to the ground water for any industrial purpose or for irrigation with no restrictions as to crops. Studies made in California indicate that after filtration through four feet of sandy loam, a primary effluent or a completely treated sewage will comply bacteriologically with the U.S. Public Health Standards. Steel says that there appears to be no reason except aesthetic, why treated sewage should not be used, where conditions are favorable, to replenish dwindling ground waters by seepage from open basins or recharge wells and to use such ground waters for public use as well as industrial and agricultural uses. No objections to the ponds have been reported by residents living one-quarter of a mile from oxidation ponds.

Babbit and Bauman [5] say that the cultivation of fish in dilute sewage plant effluents can be done successfully. These authors also report on the replenishment of ground water by seepage from such ponds, citing a reference by G.T. Orlob and R.G. Butler. [6]

An outstanding advantage of the use of sewage effluent to supplement water supplies in the Everglades Park is that the quantity is approximately uniform throughout the year, and as the population of the urban area increases, the quantity of effluent will rise in direct proportion. Looking forward to the year 1970, when there will probably be 2 million people living in Dade County, there could be available 200 million gallons per day as effluent from the primary sedimentation stage in the sewage treatment plant. This is 613 acre feet per day, or 215,000 acre feet per year. With 4 million people in 1980, the quantity could be 430,000 acre feet per year, wet year or dry. As the thirsty population of the municipal area has pushed its well fields out into the Conservation Area No. 3, and greatly reduced the seepage south into the Park during dry years, this may be about all the water that will seep into the Park since that flowing south from the Tamiami Trail may have been previously intercepted by the recharge into the ground in the underlying aquifer. This quantity will at least be as much as the Park has received from along the Tamiami Trail on the average for the last 17 years, and a great deal more than has been available during dry years.

The Dade County Water Conservation District

This district was organized in 1945 and has power to carry out any measures to conserve water resources, construct necessary works and to establish the levels to be maintained in all fresh waters of the County. It has power to levy taxes to pay for its operations. Canals were enlarged to reduce flood heights, and gated control structures in the canals were built to hold up levels in dry weather. The work of the Conservation district has been most effective in controlling salt water infiltration, and the body is to be commended most highly for its continued devotion to duty.

The Federal Water Control Project

The Conservation Areas which have been repeatedly mentioned and which are shown on Plate I have been built by a Federal Project. The destructive floods of 1947 resulted in the passage of a federal law, (House Document 643, 80th Congress, 2nd Session), which appropriated money for the control of the level of Lake Okeechobee and for control of floods in the St. Johns and Kissimmee Rivers. The State of Florida created the Central and Southern Flood Control District. In Dade County, the Federal project is practically the same as the project for the County Conservation District. Federal funds have been appropriated at the rate of several million dollars annually. This money has been spent principally for the construction of levees. Numbers L-30, L-31, L-33 and L-67A have been completed, and L-28 is well advanced. These levees are designed to enclose large areas, called Conservation Pools. These extend south from a point west of West Palm Beach down to the Tamiami Trail. The area of each, the storage capacity, and the amount of water which it is estimated will be stored in them is as follows:

The reason that Pool No. 1 will store much more water than its capacity is that the water will pass continually down into the other pools. Pool No. 1 has been designated as a Wildlife Refuge. Presumably all land within these Conservation Areas is federally owned, and none can be sold or leased for private occupancy without an Act of Congress.

It must be repeated for emphasis that the creation of these Conservation Pools or Areas is a most constructive step forward in improving the water supply situation in the whole area. The essential reason for the creation of them was to provide a place for the storage of flood water without seeing it all drained out to sea, and lost forever; and hence to provide water for re charge of the Biscayne aquifer. It has been pointed out that so long as the wells serving Greater Miami are all several miles to the east of Conservation Area No. 3, no recharge of the aquifer will come from the water on the Conservation Area. There is not head enough to move water that far. Hence the 1,696,000 acre feet of water in Conservation Area No. 3, standing an average of three feet deep over the 926 square miles will partly evaporate, but some will seep down through the Tamiami Trail into the Park. The engineer, Lamar Johnson whose report has been quoted several times, estimates that the amount will be 588,000 acre feet, as compared with the present seepage of 473,200 acre feet along the same frontage. This is a substantial increase.

Another important area where much additional water can get into the Park is along the north-south boundary between the Park and the Southwest Dade Area. Mr. A. Van V. Dunn, Formerly Chief, Branch of Water Resources, National Park Service, made an estimate that an average of 160,000 acre feet of water could be pumped into the head of Shark River Slough by two pumps of large capacity installed at points respectively 7 miles and 10 miles south of the Tamiami Trail along that common boundary of Park and the Southwest Dade Area. Neither these pumps, nor even the levee called "67 Ext" to be built along that boundary are yet in place, nor even assured. These pumps will not raise water from wells, but rather standing water in the head of Shark River Slough within the Southwest Dade Area. Presumably this water would be available only during the wet season, and perhaps not then if heavy pumping by future wells which may be drilled in the Southwest Dade Area induces infiltration for recharge.

Of the two pumps shown on Mr. Dunn's map (not reproduced here) the one planned seven miles from the Tamiami Trail will be installed instead just south of the Tamiami Trail. The other pump at 10 miles south of the Trail is still under consideration for future installation.

During wet years, when the storage capacity of Conservation Area No. 3 is filled, then there will be a large amount of excess water, much of which will flow freely south into the Park along the Tamiami Trail. The problem then will be to retain enough of this water north of the Shark River Slough, so that it will not run off too rapidly into the Gulf of Mexico and be dissipated. To retain this flood water, it is recommended that consideration be given to the construction of a levee, 18 miles long and running in a southeasterly direction. The center point of this proposed levee will be in the middle of the Shark River Slough, some 15 miles due south of the Tamiami Trail. To be specific, that center point will be in Section 22, T.56 S, R. 35 E. The location of the suggested levee is shown on Plate I.

The purpose of the levee is not to retain all of the water until it evaporates, but rather to retard its southwestward flow, so that the rookeries will have plenty of water during the nesting season. During dry years there will be no water to retain behind this proposed levee. In such years, if the rookeries receive any water it will have to come from the discharge of the Park wells, and from the sewage effluent.

Conclusions and Recommendations

It is concluded that there is no possibility of ever restoring to the Everglades Park the amount of water that area received in "predrainage canal" times. However, the establishment of the Conservation Areas by the construction of levees by the Federal Water Control Project has been a most constructive development, and will add some water to the Park area from seepage during dry and normal years, and during wet years, there will be a great deal of water available to the Park, running down from the Conservation Areas.

At the present time, there is no conflict of interest for available water for the needs of the people of Greater Miami, and for the Park, and so long as the needs of the people can be met from wells in or near their present positions, there will be no conflict. Up until 1980, when the population of Greater Miami may reach 4 million, the needs of the people should be satisfied from wells drilled well east of the Park Area, and east of Conservation Area No. 3. 1980 is only sixteen years away; hence it is very pertinent to look beyond that time when a conflict of interest can develop between people and Park.

Additional water for the Park can be made available through wells drilled in the Park along its northern boundary, and its western boundary south of 40-mile Bend. Recharge of the aquifer will be promoted by the water seeping down from Conservation Area No. 3.

Another source, and one which could grow in quantity as the population of Greater Miami grows, is the effluent water from oxidation lagoons, treating the liquid effluent from Sewage Treatment Plants. Such water is not odoriferous, and within the tolerance of Public Health rules for infiltration to ground water for human consumption. Fish thrive in such waters. This effluent water could be a regular and continual supply, available in equal quantities in dry as well as wet years, and available in regular increments throughout the year. It could be a most helpful supplement during dry years.

¹Soil and Crop Science of Florida, Proc. vol. 20, 1960, pp 213-4.

²Parker, G.G. et al., "Water Resources of Southeastern Florida," U.S. Geological Survey, Water Supply Paper 1255, 1955, pp 198-221.

³Water Supply and Waste Water Disposal, John Wiley, 1954, p. 771.

⁴Steel, E.W., Water Supply and Sewerage, McGraw-Hill Book Co., 1960, p. 478.

⁵Sewerage and Sewage Treatment, John Wiley & Sons Book Co., New York, 1958, p. 392.

⁶Journal Sanitary Engineering Section American Society Civil Engineers, Paper 1002, June 1956.