BOARD OF COUNTY COMMISSIONERS LEON COUNTY, FLORIDA

those root mass pathways decay and minimize in number and size without the living
plant. The root mass also removes the nutrients from the stormwater when the plants take
in water for their daily needs. The volume of groundwater extracted for plant needs can
be substantial. Consider that each oak tree needs 30-40 gallons per day.
The native plants also slow the flow rate of storm water by increasing the tortuosity (more
curves and a longer flow path) and roughness (an engineering term that assigns a value
for different ground covers. A forest has greater roughness than grass and grass is better
than concrete.) The speed of flowing water has a direct relationship with its ability to
erode and sediment carrying capacity and slow speeds are crucial to preventing erosion.
Undisturbed native vegetation is denser in its coverage than any landscaping.
Undisturbed native vegetation is also more effective than any engineered structure.
(3) Alteration of the topography is mainly an aesthetic impact. In the Appalachian area
we see many former borrow areas converted into commercial property with the resulting
cliff still visible behind the building. Any recontouring of the land surface removes the
topsoil and organic component necessary for re-establishing vegetation as well as the
roots.
(4) Eroded sediments affect surface water quality by the turbidity that reduces/eliminates
water clarity. Any nutrients (from fertilizers) and pesticides previously applied to the soil
are also now in the surface water. These nutrients and pesticides behave the same as they
do in soil; encourage the growth of plants (flora) and kill small beneficial organisms
(fauna) that are part of the food chain. The net result is an imbalance of flora and fauna
where by not enough organisms remain to consume the excess plant growth.
Our area is dotted with sinkholes and other karst features that allow rapid connection
between surface water and ground water. Some of these sinkholes are located on lake
bottoms (Lake Jackson and Lake Lafayette) and other sinks are known to reverse flow,
sometimes swallowing surface water and other discharging as a spring. We have gaining
(from ground water recharge) and losing (surface water drains to ground water) streams
and these conditions can reverse during the year.
(5) Erosion affects upland and aquatic creatures by destroying their habitat by burial.
Many species have shelter in the soil and sediment, under logs and in the plants.
Sediment burial and the turbidity in the water column limit the ability of aquatic creatures
to find and capture food.
Typical stormwater treatment systems are capable of reducing the total pollutant load by
80-95% and phosphorus by 60%. Vegetation growth remains the best and most costeffective
way to remove nutrients from stormwater. In fact, the Everglades Restoration
Project is building huge Stormwater Treatment Areas (STAs) that are no different from
wetlands to reduce phosphorus.
Page 382 of 622 Posted at 5:00 p.m. on April 1, 2013