FDEP Summary of
Surface Water
Quality Trends. Changes in water quality over time are an
important indicator of the health of surface waters. Out of 841 rivers/streams,
lakes, estuaries, and coastal waters evaluated from 1995 to 2005, about 50%
were stable, about 25% were improving (in urban areas, due to improved
wastewater and stormwater treatment), and about 25% are degrading (in agricultural
areas, the
Causes of
Surface Water Impairment.
Surface Water Results
FDEP
evaluated data from 5,800 waterbodies statewide
against state water quality standards. There were sufficient data to evaluate
(by area or length) 50% of the state’s rivers and streams, 75% of its lakes,
and 90% of its estuaries. Ninety different chemical and biological parameters
were evaluated.
This
report encompasses results from the first 4 years of a 5-year cycle that
evaluates water quality for the entire state by focusing on 20% of the state
each year for 5 years. The figure on the next page shows that most surface
water quality problems are found in highly urbanized central and south Florida
(except for mercury contamination, which is statewide). Areas with intense
agricultural and industrial use are also associated with poor water quality.
Water quality in the northwest and west-central sections of the state is
generally better than in other areas. Of the waterbodies
that were evaluated, poor water quality
was found in 50% of the river and stream miles, 60% of the lake acres (excluding Lake Okeechobee), and 60% of the square miles of estuaries.
To date, with 80% of the state evaluated, approximately 1,066 TMDLs will be required for 223
The percentage of unpolluted waterbodies for each surface water classification was
as follows:
• Class 1 waters (potable supplies), which supply about 13% of
water: 17% of river/stream miles and 0%
of lakes.
• Class II waters (shellfish propagation or harvesting): 10% of river/stream miles and 12% of
estuarine square miles.
• Class III fresh waters (recreation, propagation, and
maintenance of a healthy,
well-balanced population of fish and wildlife): 7% of river/stream miles and 10%
of lake acres.
• Class III marine waters (recreation, propagation, and
maintenance of a healthy,
well-balanced population of fish and wildlife): 15% of estuarine square miles
and 25% of coastal square miles.
All
estuaries and coastal waters have been tested for mercury, and consumption
advisories have been established for a number of fish species. The figure on
the next page shows the results for mercury only. The TMDLs
for mercury will be developed statewide and are due in 2011.
Despite
• Excess fertilizer from agricultural operations (particularly high levels of
nitrates
are found underneath intense,
center-pivot agricultural operations associated
with dairy farming; crops; and areas
with wastewater reuse),
• Excess fertilizer from urban lawns and landscapes, and
• Excess nutrients leaching into
ground water from septic tanks.
Summary:
The
evaluation used historical ground water data from monitoring networks, private wells,
and public water systems. The results were as follows:
• Volatile organics—Benzene most frequently exceeded its
maximum
contaminant level (MCL). Trichloroethene
(TCE) was the second most
frequently detected compound above its MCL in
samples from public water
systems and private wells, closely followed
by tetrachloroethene. The most
frequently repeated detections in public water
systems occurred in southeast
• Pesticides—In public water system samples, the
greatest number of
exceedances were for lindane, toxaphene, and methoxychlor
(mainly detected
in the 1980s and since banned). In
private wells, most exceedances were for
another banned compound, ethylene dibromide (EDB), which was found in
samples collected in the 1980s. More recent
issues in private wells were
identified for bromacil
and alachlor.
• Nitrates—Exceedances of the MCL were found in samples
from 156 public
water systems, with the greatest number
found in or near agricultural areas.
Most private well exceedances were also found in agricultural areas.
• Metals—Samples from public water systems
have historically exceeded MCLs
for 1 or more primary metals; however,
some data, particularly for lead and
cadmium, may not be valid because of the
influences of metal piping and tanks
used to transport and store water. In
samples from private drinking water wells,
exceedances were most frequent for arsenic and lead, with lead most
often
associated with plumbing or fixtures rather
than ground water.
• Radionuclides—Most exceedances
in samples from public water systems
were found in the large phosphate-mining
area of west-central
Radioactivity is a natural
characteristic of phosphate.
• Sodium—Most of the elevated sodium
concentrations were found in public
water systems in southeast and southwest
intrusion and upwelling of saline waters are
serious concerns.
• Trihalomethanes (THMs)—Most exceedances
in public water systems were
found in southeastern
byproducts of the disinfection of water
containing organic matter.
• Bacteria—Bacterial contamination was an issue
for monitoring well samples
and is a common issue with water from
private wells and water systems. Well
contamination is typically from a localized
source.
Sources of
Ground Water Degradation. The most significant sources
were petroleum sites,drycleaners,
hazardous waste sites, and nonpoint pollution.
Ground
Water–Surface Water Interaction. Nutrients,
dissolved oxygen, and iron were the ground water constituents most frequently
identified with affected surface waters that exceed criteria. Ground water
inflows account for most of the water in many
Source:
Integrated Water Quality Assessment for
and 303(d) List Update,
http://www.dep.state.fl.us/water/tmdl/docs/2006_Integrated_Report.pdf
The DEP’s
primary responsibility in the implementation of chapter 62-524 has been the delineation
of areas of ground water contamination affecting potable water supplies or
wells and the corresponding development of maps identifying those areas. Where
data are incomplete, a 1000-foot protective setback is placed around the
contaminated site or well to estimate the extent of the contaminated plume.
The contaminated sites and associated plumes are plotted on maps and each plume
is labeled with a unique identifier that can be used to determine the
contaminants contained therein. A well permitted in a delineated area must be
tested for the contaminants for which the area was delineated before it can be
cleared for use. While areas have been
delineated based on detection's of solvents and gasoline, EDB, detected in 38
counties statewide, has been the primary contaminant serving as the basis for
the 427,897 acres delineated under Chapter 62-524(PDF) of the Florida Administrative Code.
http://www.dep.state.fl.us/water/groundwater/delineate.htm
