THE FLORIDA
EVERGLADES
A Model of Destruction
From: FICUS
Network - USF University of South Florida
More recently, the
Everglades has become a classic example of widespread
environmental destruction. Although in its 5,000 years
of existence, the Everglades has supported an
extraordinary quantity and variety of plant and animal
life, we have taken less than a century to damage
seriously or to alter most of it. The current
superintendent of Everglades National Park calls it the
most threatened park in the country, and one in a state
of biological collapse.
The 1850 federal Swamp
and Overflowed Lands Act gave the Everglades to
Florida provided it could be drained. While private,
turn-of-the-century efforts to drain large areas of the
Everglades failed, soon afterwards public works
succeeded. By the 1930s, 400 miles of drainage canals
had been built.
Agriculture and cattle
constituted the primary wave of invasion, quickly
followed by rapid urban development. What was once the
Everglades now contains more than 40 percent of
Florida's population and produces half of all the winter
vegetables sold in the United States-in addition to
sugar and other crops. (See Chapter 15 on Florida's
Agriculture for more information on agriculture's
environmental effects.)
LOSSES WEST OF THE
COASTAL RIDGE
As part of the Central
and Southern Florida Flood Control Project, the East
Coast Protective Levee was constructed at the
eastern edge of the River of Grass. The barrier stopped
water from flowing east from the River of Grass and
allowed the area between the levee and the ridge to
drain through canals cut to the ocean. No longer subject
to periodic flooding, the area became suitable for
agriculture and later for urban development. It is now
almost entirely urban. About 160 square miles of this
severed area was Everglades marsh. With the
construction, an additional tributary watershed of about
775 square miles was severed from the Everglades.
Including lost marsh, almost 950 square miles of
watershed were lost.
THE LOSS OF LAKE
OKEECHOBEE'S WATERSHED
In works that began
near the turn of the century, 730-square-mile Lake
Okeechobee (the second largest lake entirely within the
lower 48 states) and its tributary watersheds were
severed from the Everglades. Water was diverted to the
Atlantic Ocean and Gulf of Mexico through canals-the
beginning of what would become a 1,400-mile network of
canals that lowered the lake and drained adjacent lands
for farming. The Everglades-to-Florida-Bay route was no
longer Lake Okeechobee's major outlet.
After disastrous
hurricanes in 1926 and 1928 killed thousands of people,
Lake Okeechobee was rimmed by a levee to prevent waves
from flooding inhabited farmlands, thus removing more
than 4,500 square miles from the Everglades watershed.
The levee also made the lake a useful reservoir for
agricultural irrigation water. Water that once would
have passed through Lake Okeechobee to the Everglades is
now stored for crop irrigation. When the lake goes above
its regulation stage, the surplus is discharged.
THE CREATION OF THE
EVERGLADES AGRICULTURAL AREA
Next to Lake
Okeechobee, almost 1,100 square miles of swamp and marsh
were enclosed by a levee. Already safe from Lake
Okeechobee's overflows, the impounded land, called the Everglades
Agricultural Area (EAA), was now also protected from
Everglades inflows. The EAA water table is held about
two feet below the soil surface so that the oxygen
needed by crop roots can enter the soil. When it rains,
water must be pumped out or the plants will suffer.
Seven giant pumping
stations were built to drain rainwater through canals.
While much of the EAA is still part of the Everglades
watershed, the natural flow is gone, replaced by
periodic discharges from the pumping stations. Compared
with natural runoff, the discharges are rapid. And,
unlike a marsh with standing water, the rainy season's
water does not sustain life into the dry season because
it has been pumped away. When no local rains fall, Lake
Okeechobee water irrigates the Everglades Agricultural
Area, and evapotranspiration carries the irrigation
water to the atmosphere. Water released from the lake
for irrigation seldom passes through the EAA into the
Everglades.
THE CREATION OF THE
WATER CONSERVATION AREAS
Much of the western
edge of the Everglades was also bounded by levees. Dams
created three shallow impoundments called Water
Conservation Areas (WCAs), which enclosed most of
the remaining Everglades. The WCAs were shallow marshes
with soils too poor to support agriculture. Gates now
control discharges from one WCA to the next. The last
impoundment discharges into Everglades National Park.
Compared with the original flow-resistant marsh, canals
in the WCAs speed water flow. When the Water
Conservation Areas are filled to protect against
drought, the water stagnates, and the unnatural hydroperiod,
or wet cycle, alters and stresses native communities.
The WCAs store water
for use during drought by South Dade County agriculture
and the urban populations of Monroe, Dade, Broward, and
southern Palm Beach Counties. In addition to
agricultural users, about four million people on the
lower east coast draw water from the surficial Biscayne
Aquifer. The aquifer is supplied by water released from
the WCAs when rains fail. The drought-induced releases
rapidly lower marsh water levels in the Everglades.
During severe droughts,
Lake Okeechobee water is used to replenish supplies. The
water passes through the Everglades Agricultural Area,
where some is removed by growers. The rest passes
through the Water Conservation Areas in the canals.
Because they do not overflow the canal banks, however,
drought releases to the lower east coast do not nourish
Everglades vegetation. Transmission through the WCAs is
much like a pipeline from Lake Okeechobee to South
Florida's urban and agricultural areas.
SEVERING NORTHEAST
SHARK RIVER SLOUGH
In the natural
Everglades, the River of Grass narrowed at a natural
channel, Shark River Slough. When Everglades National
Park was established, in a political compromise only the
western portion of this waterway was included. Northeast
Shark River Slough received virtually no water,
drastically altering the ecology of that part of the
original Everglades.
THE RAINFALL PLAN
We now know what
drastic overdrainage has done to the Everglades, and we
understand the detrimental effects of maintaining long
periods of deep, standing water. After a severe drought
during which no water was delivered to Everglades
National Park, Congress mandated minimum flows to the
park. Adversity was to be shared among all the park's
users. Yet the minimum flows harmed the park because
they were carried out without regard for ecological
timing. Congress then authorized the park and the water
management district to experiment with solutions, and
the Rainfall Plan was the last in a series of efforts to
try to correct the problem.
The plan simulated the
flow that would have entered the park at Shark River
Slough under natural conditions. While the principle is
good, existing data may not accurately represent the
predrainage Everglades, resulting in lower flows to
Everglades National Park. The range of fluctuations may
be too low, and if water levels are high, water must be
released to protect the levee's structural integrity.
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For information on the
Everglades and the Florida panther, contact the
following agencies (see the listing of governmental
agencies in the back of the guide):
