OPEN FILE REPORT NO. 85


charge rates are driven by the rate of recharge, climatic fluctuations often have a major
effect on spring flow. During 1998 2001, Florida suffered a major drought with a rainfall
deficit totaling more than 50 inches (127 cm). The resulting reduction in recharge from the
drought and normal withdrawals caused a lowering of the potentiometric surface in the
FAS. Many first order magnitude springs experienced a significant flow reduction. Some
springs, such as Hornsby Spring, ceased flowing completely. The flow data given for each
first order magnitude spring (see individual spring descriptions) reflects the drought-influ-
enced flows.

 WATER QUALITY

Methodology

 Seventeen springs, eight spring groups/systems, seven river rises, and one karst win-
dow (49 vents total) were sampled from 25 September 2001 through 15 November 2001.
Tidally influenced springs (10) were sampled at low tide to minimize the influence of salt
water on the water-quality samples. Standard FDEP sampling protocols were followed for
each sampling event (Morse et al., 2001).

Field Parameters

 Temperature, dissolved oxygen, specific conductance, and pH were measured using
Hydrolab Quanta and YSI data sonde (model no. 6920) and data logger (model no. 6100).
Instruments were calibrated twice daily, before and after sampling events. For quality
assurance purposes, field reference standards were analyzed every five to ten samples and
ten equipment blanks were submitted to the FDEP Bureau of Laboratories throughout the
sampling period.

 To begin each sampling event, two stainless steel weights were attached to polyethyl-
ene tubing (3/8" O.D. x 0.062" wall) which was then lowered into the spring vent opening,
ensuring the intake line was not influenced by surrounding surface water. Masterflex tub-
ing was attached to the other end, run through a Master Flex E/S portable peristaltic pump
(model no. 07571-00), and the discharge line was fed directly into a closed system flow cham-
ber. The data sonde was inserted into the flow chamber and water was pumped through
with a constant flow rate between 0.25 and 1 gallon/minute. No purge was required because
springs are considered already purged. The field parameter values were recorded after the
field meter displayed a stable reading (approximately 10 minutes). The flow chamber was
removed and sampling was conducted directly from the freshly cut masterflex discharge
line.

 Two exceptions to this sampling method occurred at Wakulla Spring and Homosassa
Springs. Both springs have pre-set pipes running down into the cave systems where the
spring vents are located. In the case of Homosassa Springs, tubes from the three vents con-
verge at an outlet box with three valves inside, one for each vent. Sampling is conducted
from these valves. At Wakulla Spring, the pipe runs to a pump on shore from which sam-
pling is conducted. The sampling system was designed and operated by Northwest Florida
Water Management District (NWFWMD) (Wakulla Spring) and Southwest Florida Water
Management District (SWFWMD) (Homosassa Springs). Each tube is purged for 10 min-