BULLETIN NO. 68


(2004), "those parts of surface-water and
groundwater basins that contribute to the flow of
a spring" are called springsheds. Given the
proximity and hydraulic interrelationships
among the springsheds of the Coastal Springs
Groundwater Basin, the term "Springshed
Group," (analogous to a "Group" in
lithostratigraphic nomenclature) is herein
introduced to characterize this and similar
regions of coalescing springsheds (e.g., Coastal
Springs Springshed Group). Copeland (2003a)
compiled a Florida springs classification system
and glossary to facilitate standardized use of
springs-related nomenclature among Florida's
various technical (i.e. cave divers), scientific and
regulatory/planning communities.

 The Coastal Springs Springshed Group and
the many other springs and springsheds in the
study area support unique ecosystems that
harbor diverse flora and fauna (Scott et al.,
2004; Champion and Starks, 2001). When water
quality and quantity decline, these ecosystems
are adversely affected. The magnitude and
nature of the threats varies within each
springshed based on land use and geology
(Hartnett, 2000; Florida Department of
Community Affairs and Florida Department of
Environmental Protection, 2002). It is
noteworthy that springshed boundaries are time-
dependent; they migrate in response to
anthropogenic activity (e.g.,
pumping/withdrawal) and seasonal/climatic
effects on the potentiometric surface (DeHan,
2004; Greenhalgh, 2004; Scott et al., 2004).

 Since the 1970's scientists have documented
a decline in water quality in most of Florida's
springs especially with regard to nutrients (Jones
et al., 1998; Hartnett, 2000; Copeland, 2003b).
Nitrate is of particular concern as high amounts
may lead to excessive growth and eventual
eutrophication of surface water bodies. Nuisance
and exotic plants can cause reduction of water
flow, reduction of dissolved oxygen and habitat
changes (Hartnett, 2000). Nitrate has been a
concern in SWFWMD for many years as
increased levels of nitrates are being detected at
many springs (Jones et al., 1997). Natural
background concentration of nitrates in the FAS
is less than 0.01 mg/L (Champion and Starks,


2001). Florida government agencies have
recently proposed best management practices
(BMPs) to protect and conserve Florida's
springs (Florida Department of Community
Affairs and Florida Department of
Environmental Protection, 2002).

 Spring-water quantity is another issue
associated with development and population
growth. Under redevelopment conditions
springs accounted for about 84 percent of water
discharged from the FAS (Ryder, 1985). As
development increases and more well fields are
used, the potentiometric surface of the FAS is
lowered. This results in lower spring discharge,
which can then result in changes in water quality
(Lee, 1998). Spring flows become dramatically
reduced or eliminated by over-pumping water
from the aquifer. Near coastal zones, changes in
aquifer conditions can also affect the location of
the transition zone between fresh and salt water
(Scott et al., 2004). As spring discharge rates
decrease, calcium and magnesium have been
observed to increase possibly owing to upcoming
or the removal of water from intergranular
storage (Rick Copeland, personal
communication, 2006). Although not fully
established at the current time, preliminary
evidence suggests that the upcoming of sulfates
and other constituents (i.e., micronutrients) may
be contributing to algal development in springs
(Sam Upchurch, personal communication,
2006). Corresponding increases in chlorides
may also be observed in the spring water as
discharge rates decrease. These conditions also
allow migration of saltwater further inland (Lee,
1998).

Hydrogeology

 Three major hydrostratigraphic units occur in
west-central Florida: the surficial aquifer system
(SAS), the intermediate aquifer
system/intermediate confining unit (IAS/ICU)
and the Floridan aquifer system (FAS). Miller
(1986) divides the FAS into two zones of higher
permeability: the Upper Floridan aquifer (UFA)
and the Lower Floridan aquifer (LFA), which
are separated by one or more regional confining
units (Middle Floridan confining unit; MFCU).