The Determination of Minimum Flows for Sulphur Springs, Tampa

DRAFT
As discussed in Section 2.5.3, the temperature of discharge from Sulphur Spring pool
shows only minor seasonal variations. Data from the vertical profiles showed some
seasonal variation, with average temperature values for all stations in the run ranging
from 24.4 o C on March 4, to 28.5 o C on June 12, 2002. These results also were likely
affected by periodic incursion of river water into the run at low flows. Greater elaboration
concerning temperature is provided at the end of this chapter with regard to use of the
spring run and river by the Florida Manatees.
Other than vertical profile measurements, no other water quality data were collected in
the spring run. However, it is probably reasonable to conclude that under conditions of
normal flow (no withdrawals), the concentrations of most parameters in the spring run
(e.g. nutrients, BOD and suspended solids) are similar to the spring pool. The volume of
the spring run is relatively small, and under conditions of even intermediate rates of
flow, the water in the run is replaced by spring water many times a day. Under
conditions of no flow or very low rates of flow, it is likely that the concentrations of water
chemistry constituents are affected by incursions of water from the Lower Hillsborough
River, although no data were collected to support this hypothesis.
3.7 Biological habitats and communities in the spring run
3.7.1 Benthic habitats
As discussed in Section 2.1, the spring run is fairly shallow, with most water depths less
than two feet deep at mean tide. There are virtually no snags or aquatic macrophytes in
the run. Bottom habitats reported by the University of Florida during 2000 consisted of
bare sediments and sediments covered by filamentous algae (Allen et al. 2001).
Sediments were classified to a macro-level scale using the Wentworth classification
scheme (McMahon et al. 1996). The sediments were predominantly sand, with much
lesser fractions of slit, shell, pebble and rock.
The algae that were common on the sediments were comprised of the genera Melosira,
a diatom that can form filamentous aggregations, and filamentous green algae of the
genus Cladorphoa. Attached and floating mats of filamentous algae were widely
distributed in the spring run during the no flow periods of 2000 and 2001. The return of
high flows in 2002 and 2003 reduced the abundance of these algal mats, as evidenced
by percent coverage values of less than 6 percent at stations as measured by UF
biologists in 2003 (SWFWMD, unpublished data).
3.7.2 Shoreline vegetation
The shoreline of Sulphur Springs is hardened by a retaining wall, but shoreline plants
have become established waterward of the wall over approximately three-fourths of the
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