Ask Margaret
by Margaret Word Burnside
Is saltwater intrusion becoming a
problem is our area?
F.T., South Tampa
Saltwater intrusion actually already is a problem in the
Tampa Bay area, in Florida and in other coastal and eastern
states, as well as in several parts of the world. In fact, saltwater
intrusion has been recognized as an important ecological
concern since as early as the mid-1800s, and possibly even
before that.
Basically, saltwater intrusion is the seepage of seawater
into freshwater aquifers. This can occur when the sea level
rises excessively, usually due to severe storms or global
warming. Saltwater intrusion can also take place when an
overabundance of freshwater is removed from aquifers and
other natural water sources by pumping, evaporation or other
means. This can result in an abnormal displacement of water,
as the fresh and salt waters inadvertently reverse their natural
courses. Instead of freshwater flowing to and discharging
into lower level waterways, saltwater is pushed or pulled
upwards and inland. Since fresh ground water is not as dense
as saltwater, the freshwater floats on top of the saltwater with
each exerting pressure against the other. The fresh and salty
waters eventually begin to interface with one another. This
salt water invasion progressively raises the clear waters’ saline
and chloride concentrations, thus increasing its brackishness
and rendering it unacceptable for human, animal and plant
consumption.
Extensive development along coastlines, as well as further
inland, is depleting valuable and necessary freshwater sources.
Wells are being dug; and aquifers are being exploited. Water is
even being transported inland for both human and agricultural
use from protected areas such as the Chassahowitzka
National Wildlife Refuge pictured here, which is just north
of the Tampa Bay area. Alarmingly, this unfortunate practice
of depleting natural water sources appears to be sanctioned
by the very people, including those of the Southwest Florida
Water Management District known as SWIFTMUD, who have
been charged with safeguarding the Chassahowitzka, its fivemile
long spring-fed river and other fragile and primordial
spring-fed estuaries and wetlands.
The resulting saltwater intrusion has damaged water
supplies, wildlife and forests. Hundreds of species of birds, a
variety of small animals and even snakes, wild boars and bears,
plus porpoises, manatees, otters and fish find life increasingly
difficult once salt water intrusion contaminates their once
pristine homes and refuges. They are also joined by the
threat of alligators, which can thrive in the polluted brackish
waters. Salt-intolerant hardwood trees and other plants also
become victims within irreversibly imbalanced areas. Fragile
wetlands and other formerly lush areas along our Gulf
Coast are suffering because of saltwater intrusion. Formerly
clear, azure freshwater creeks are becoming salty, murky
and progressively less able to sustain life. Once dense salt
intolerant semi-tropical hardwood trees that were festooned
with mosses, ferns and bromeliads have been irreversibly
destroyed. They now sit dormant as open grassy plains spotted
with lone palm trees, dead tree stumps and nature’s rubble.
Unfortunately, if we don’t change our ways of permitting and
handling saltwater intrusion, Chassahowitzka’s plight of saltdamaged
sawgrass savannas may foretell of Florida’s future
ecosystem loss.
Extensive damage has already occurred and, unfortunately,
appears to be accelerating. Los Angeles, New York City and
South Florida have been experiencing water crises for years.
Although the Tampa Bay area’s relatively lower population
demands less water and its larger green spaces enable below
ground rehydration through percolation, we have already
experienced necessary sprinkling restrictions and the loss
of wetlands and other open spaces. The undeveloped,
supposedly protected, nearby Chassahowitzka area’s plight
should be a serious warning, which is well worth heeding.
124 TAMPA BAY MAGAZINE MARCH/APRIL 2016