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PREFACE 2003 Lake Water Quality Report Limnology,
the science of freshwater ecosystems has been studied for many years.
Much of the data has been collected on northern U.S. lakes and
European lakes. Many of the
Central Florida lakes cannot be characterized using the information
derived from those lakes. Water
quality in Central Florida lakes is influenced by a variety of natural and
cultural factors. There are
physical, biological and chemical influences and they do not work
independently. Some physical
factors include flushing and the topography of the lake.
An example of a biological factor is the plant characteristics in a
lake. Chemical factors include nutrient input to lakes, such as from
stormwater runoff. The
shape and depth of a lake naturally affects the water quality.
Central Florida lakes are generally characterized as shallow,
bowl-shaped lakes often formed from sinkholes.
Wind and sun help to keep the lakes mixed and heated more
consistently than the temperate lakes to the north, although most City
lakes stratify into distinct layers from time to time.
Lakes undergo a flushing process.
Rain, groundwater and connections from other lakes bring water into
a lake. Evaporation, drainage wells, and connections to other lakes
allow water to leave a lake. The
amount of time that the same water remains in a lake varies from lake to
lake and can affect water quality. Shoreline
and bottom vegetation also affects the water quality in our lakes.
Nutrients that find their way into lakes will promote vegetative
growth along the shoreline and down to about 4 meters deep, depending on
the water clarity. If the
vegetation is removed (with herbicide, by hand, or by grass carp), algae
will grow quickly with the availability of the nutrients.
In an ideal situation, there is a balance between vegetation and
nutrient input to the lake. There
are desirable types of vegetation, which are native to Central Florida
lakes as well as nuisance and exotic plants.
Removal of exotic and nuisance plants is a common practice in lake
management. One factor, which
helps prevent a lake from becoming algae dominated, is desirable
vegetation. Stormwater
runoff is the water that flows over the land following a rain event.
Historically, the volume of stormwater runoff was lower than it is
now because much of the rainwater was soaked into pervious surfaces
covered by vegetation. Urbanization
brought roads, rooftops, parking lots, and other impervious surfaces.
Stormwater runoff has increased in amount and velocity of flow with
these impervious surfaces. Stormwater
runoff affects the water quality of lakes and groundwater in Orlando
because it collects many different substances in its path such as
automotive fluids, dirt, nutrients (nitrogen and phosphorus), bacteria,
leaves and litter, carrying them to our water bodies.
These pollutants are harmful to fish and other aquatic wildlife.
The Orlando area also has drainage wells, direct conduits to the
upper aquifer, taking stormwater runoff and lake overflow and mixing it
with the groundwater. Many
of the substances found in stormwater are unintentional or circumstantial.
For example, automobiles deposit petroleum products and heavy
metals on the road with normal usage.
Atmospheric deposition of nitrogen occurs naturally, as well.
Leaves fall from trees into roads and parking lots, eventually
washing into a lake or drainage well.
However, some of the undesirable substances found in stormwater
runoff are placed there intentionally or through neglect by improper
disposal of waste liquids and solids.
Any wastewater or other material allowed to drain to a street,
alley, parking lot, driveway, or storm system potentially impacts the
water quality of an area lake or the groundwater. Does
that mean the water quality of our lakes and groundwater must get worse?
Not necessarily, efforts by the public and private sectors of the
community can and do stop the decline of water quality of our lakes. In fact, in some cases, the water quality can be and is
enhanced by specific behaviors and/or structural devices. Pollution prevention is the most cost-effective and easiest
method of getting good water quality in lakes. Strict
local and state regulations require new development and redevelopment to
address water quality issues, especially concerning stormwater.
Stormwater ponds collect and treat stormwater, as well as provide
flood control. Innovative
retro-fit stormwater treatment projects provide stormwater treatment and
flood control in built out and poorly drained areas.
The Greenwood Urban Wetlands near the intersection of Mills Avenue
and Anderson Street is a good example of this. The
private sector can help prevent lake water quality degradation, as well.
Individuals who do not deposit the leaves and grass clippings from
their yards into the street and who follow the label directions when
fertilizing their lawns are not contributing to lake pollution.
Businesses who dispose of their liquid waste through the sanitary
sewer system where it can be treated (instead of the storm system) are
preventing lake pollution. Construction
sites where dirt is kept on site, prevent siltation of waterbodies and
keep the pollutants bound to the sediments and out of waterbodies. These are just a few examples of ways to prevent lake pollution. For more information about our lake water quality, contact the City of Orlando Stormwater Utility Division at 407-246-2370.
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