The Determination of Minimum Flows for Sulphur Springs, Tampa

DRAFT
and possibly even high sulfide concentrations in waters discharging to the spring run.
No dissolved oxygen measurements were made in the spring run when the gates were
open, and it is not known to what extent that discharge from the pool became
oxygenated in the spring run. Similarly, there are no sulfide data for the spring pool or
run on which to make reasonable inferences. If the gates need to be opened in the
future, there should be plans to mechanically aerate the spring discharge if this is
shown to be a problem.
In sum, it is not possible to evaluate to what degree hypoxia during 1999 and 2000 may
have been a factor in the change in invertebrate community composition of the spring
run. It is reasonable to conclude, however, that the dramatic salinity changes that
occurred would have affected at least some of the less euryhaline invertebrate species
in the spring run. The potential effect of different minimum flows on the invertebrate
community in the spring run is discussed in Chapter 5.
3.8 Fish populations in the spring run
The species composition of the fish community that inhabits Sulphur Springs Run is
closely linked to fish populations in the Lower Hillsborough River. Fish populations in
the river have been described in two reports related to the use of the Hillsborough River
for water supply. The first study by Water and Air Research and SDI Environmental
Services (WAR/SDI 1995) collected fish data in the lower river on a monthly basis for
two years during 1991 -1993. Life stages that were collected included egg, larval and
juvenile stages collected by 500 micron mesh plankton nets, and juvenile and adult
stages collected by seines.
A second major investigation of the fish fauna of the lower river is currently ongoing as
part of the Hydrobiological Monitoring Program (HBMP) for Tampa Bay Water, a
regional Water Supply Authority. The HBMP is being conducted by the principal firm
PBSJ, Inc., with participation by the University of South Florida College of Marine
Science and the Florida Fish and Wildlife Conservation Commission’s Florida Marine
Research Institute. Data collection for this project began in May of 2000 and is
scheduled for at least a few more years. Although the distribution of collection sites is
different than the WAR/SDI study, this study similarly collects both ichthyoplankton and
juvenile life stages throughout the lower Hillsborough River on a monthly basis. Results
from this study for the years 2000 – 2002 were presented in a year three interpretive
report by PBSJ (2003).
Both the WAR/SDI and PBSJ reports presented extensive information on other
biological communities (e.g. vegetation, benthic invertebrates) in the Lower Hillsborough
River, but included no sampling in Sulphur Springs Run. However, in 2000, the District
funded a study of the fish fauna in Sulphur Springs Run by the University of Florida that
was conducted in conjunction with the invertebrate studies described in Section 3.7.3.2.
University staff have sampled fishes in the spring using seines seven times since May
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