The Determination of Minimum Flows for Sulphur Springs, Tampa

DRAFT
Table 5-1 includes dates and the rates of springflow on the days of field sampling for
each experiment. The daily flow values from the spring pool during each experiment are
listed in Appendix G, along with flows for several days preceding and following the
experiment and the daily mean, minimum, and maximum salinity value at the spring run
recorder for all days listed.
The design of the flow experiments involved monitoring the movement of brackish water
into the upper spring run. The experiments were discontinued in the summer of 2002
when a period of high flows began at the Hillsborough River dam, causing the river to be
fresh near the Sulphur Springs outfall. Due to unusually wet conditions during the
remainder of 2002 and 2003, high flows continued at the dam, thus effectively ending
the experimental period in June 2002.
Table 5-1 Rates of springflow and dates of salinity sampling for controlled
release experiments from Sulphur Springs pool
Experiment Rate of springflow on days when salinity Dates of salinity profiles
profiles were made
1 31 & 23 cfs November 26 & 30, 2001
2 31 & 19 cfs December 3 & 6, 2001
3 31 & 19 cfs December 10 and 13, 2001
4 25 & 15 cfs March 5 and 8, 2002
5 13 cfs June 12, 2002
6 2.5 cfs June 20, 2002
5.2.3 Salinity response during the controlled release experiments
Vertical profiles of specific conductance, salinity, temperature, pH, and dissolved oxygen
were measured in the upper spring run and lower spring run for each sampling event.
Salinity data were collected at a systematic series of 21 sites in the upper spring run and
3 sites in the lower spring run (Figure 5-2). The sites were numbered from upstream to
downstream within the spring run in triplets. For example, sites 1, 2, and 3 were located
laterally across the most upstream zone of the upper spring run; sites 19, 20, and 21
were located laterally across the most downstream zone in the upper spring run, and
sites 22, 23 and 24 were located laterally across the lower run.
Box and whisker plots for salinity values measured at the 24 stations on the last
sampling day for each experiment are shown in Figures 5-3 a through f. Salinity values
from all depths at each station are included. With the exception of Experiment 2, salinity
values at stations in the lower run were higher that stations in the upper run. These
results indicate that salinity in the lower run is much more sensitive to the effects of
reduced flows than the upper run, as the hydraulics of the lower run are more linked to
the Lower Hillsborough River, while the upper run is more isolated from the river due to
the presence of the weir.
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