Water Managenment District
E3 S P. O. BOX 457 BROOKSVILLE, FLORIDA 33512
h M DERRILL McATEER, Chairman, Brooksville THOMAS VAN der VEER, Secretary, Yankeetown S. C. BEXLEY, JR., Land O' Lakes
G ROBERT E. VAUGHN, Vice Chairman, Brandon JOHN A. ANDERSON, St. Petersburg JOE E. HILL, Leesburg
J. R. GRAW, Treasurer, Ocala HERMAN BEVILLE, Bushnell N. BROOKS JOHNS, Lakeland
Donald R. Feaster, Executive Director
February 4, 1975 ..
FE 5-1975 Bj
Mr. L. M. Blain
Post Office Box 1363
Tampa, Florida 33601
Dear Mr. Blain:
In your letter of January 24 to E. D. Vergara regarding the Department
of Natural Resources' Draft Environmental statement on the Tampa Bypass
Canal, you asked for the dates of completion for those sections of the
canal downstream from Structure 160. Section 1A was completed in
August 1967; Section IB, in July 1972; and Section 1C, in December 1973.
It might be of some value to you also to have some pertinent information
from the Final Environmental Statement, C-135 and Lower Hillsborough
River Basin, Four Rivers Basin prepared by the Corps of Engineers and
dated April 1974. In section 3.08, the statement addresses the impact
of fresh water discharge into estuarine areas of Hillsborough Bay. It
concludes that (1) the periodic flushing by the canal, during periods of
heavy rainfall, would have a beneficial effect upon the ecology of the
Palm River and the bay by flushing pollutants from the area; and (2) the
net decrease in the amount of fresh water entering the Bay would have a
beneficial effect by reducing an existing problem caused by the brackish
algae GRACALARIA. This algae is periodically killed by an increase in
fresh water entering the bay from the river and reducing the salinity
level below acceptable parameters for the algae. The decay of the dead
plants causes a reduction in dissolved oxygen in the bay and also re-
leases hydrogen sulfide into the air to create a noxious odor.
I am enclosing a copy of the appropriate sections for your information if
you desire a greater degree of detail.
MG Q6 EVANS
Spa, Projects Assistant
Possible adverse effects on both the potentiometric surface and tlhe
W'4ter table, control structures S-161, S-159, and particularly S-162
''e been designed with the capability of holding canal pool levels in
t area north of S-162, east of S-161, and soutl of S-159 up to 15 feet.
ie USGS-Corps of Engineers' 1972 survey indicated that the Eureka Springs-
1,rney Flats area would be affected tle most by the proposed construction
ith a probable drawdown of up to 3 feet in the Floridan Aquifer water level
"t the canal and up to 2 feet drawdown at 10,000 feet from the canal, dimin-
iSing rapidly beyond that point. These expected drawdowns could result in
t'e loss of flow in some springs and a slight reduction in surface water
Levels at points within the area, emphasized by seasonal variations. Arte-
Sian water levels in the aquifer vary seasonally about 5 feet for the,region
: a whole and 2 to 3 feet in the Harney Flats area. The shallow, water-
St-le aquifer in the Harney Flats-Eureka Springs area also would be breached
i construction. Water levels in this aquifer were about 14 feet to 18 feet
f May 1972. These water levels also will reflect the canal pool levels
:'ere the aquifer is breached.
Ground elevations in the Harney Flats-Eureka Springs area vary from
a10w of approximately 13 feet to more than 20 feet. As a result, it is
or0posed that there would be seasonal regulation of water levels in
.e canal upstream of S-162 to minimize localized flooding and loss of
I ound-water flow.
70 Geologic factors. Investigations performed in the area including
|re hole samples have revealed occasional limestone "boulders" in the
`.:ea and the presence of thin beds of flint and chert which would be
. counteredd in the course of excavation. The "boulders" or sections of
SL-estone which vary in thickness and length are part of a discontinuous
|'restone formation which occurs above the Floridan Aquifer. The flint
S4 chert usually occur in thin beds within and parallel to limestone
rata and in occasional masses where a solution cavity has been filled.
Blasting may be necessary for economical excavation when hard, thick
S:-estone or flint and chert are encountered. Should blasting be employed
i i precautions and safety measures would be utilized to assure minimal
i"ruption to and impact on the environment. It is considered unlikely
.:t such blasting that might be needed'would pose any special problems.
sting will not be required in the area of the C-135 alinement north of
3 Fresh water discharge into estuarine areas of Hillsborough Bay.
?l1etion of the entire proposed project will cause alterations in the
rentt pattern of fresh-water discharge in western Hillsborough Bay and
'ay Bay. During high-water conditions, the overall quantity of fresh
er entering McKay Bay via Palm River will be greater and the period
flow of longer duration than at present.
S- ^ ,
During these conditions, there will be an adverse effect on those
estuarine benthic communities relatively intolerant of fresh water.
however, during normal or low-water periods, tlhe benthic organisms lost
ldue to the fresh water influx would reestablish themselves in the area.
h'le existing fisheries for blue crabs, mullet, and sport fishes such as
tarpon, all of which can tolerate varying salinities, are not expected to
be adversely affected. The reduction of the periodic flow of floodwater
into Hillsborough Bay will have only a minimal effect on salinity levels .
and therefore slight effect on the biota which is composed of species
tolerant of fluctuations in salinities.
The diversion of floodwaters alone will not correct the overall
water quality conditions in Hillsborough or icKay Bays. However, the
periodic increase in freshwater outfall into McKay Bay would have a .
beneficial effect by improving flushing action in the bay aid particularly .
i n decreasing flushing time for pollutants entering Palm River from trial
sources and pollutants entering the upper bay from bayfront drainage.
Further, the net decrease in the amount of fresh water entering Hlillsborough
Bay from the Hillsborough River would provide a beneficial impact by
reducing the existing problem of periodic massive kills of the brackish-
water algae Gracalaria in Hillsborough Bay.
Under existing conditions, freshwater flows of more than 2,400 c.f.s.
into Hillsborough Bay can persist for extended periods during seasonal
heavy rains. This reduces the salinities in the bay below the stress
point for Gracalaria and the algae die. As the dead algae decay, dissolved
oxygen in the water necessary for other marine life is seriously reduced.
In addition, hydrogen sulfide gas is produced by the decaying organisms
c;au;ing noxious odors in the bay area. The reduction in fresh-water flows
to Hillsborough Bay, while affecting bay salinities sufficiently to prevent
stress conditions for the Gracalaria, will not have a significant effect
on other bay aquatic life. And on the other hand, the increase in fresh-
Vuter outfall to McKay Bay under project conditions would pose no problems
of a related nature since Gracalaria is not abundant in McKay Bay.
The MacDill AFB Sewage Treatment Plant is under Federal jurisdiction. ': :
T'.e wastes are treated through an activated sludge process. It has a .
*.sifn capacity of 1.2 m.g.d. and presently serves approximately 5,870
i'"ple. The average daily flow is 0.575 m.g.d. with an average output of
10,740 pounds BODs/per year and 33,000 pounds per year of suspended
,,,lids to Tampa Bay. The plant is presently meeting State criteria for
dis barges. Future plans for operating the plant includes retaining the ... .
effluent and reuse the treated wastewater, thus eliminating the BOD and
,I's'Iled solids loads to the Tampa Bay Estuary. This will reduce the
tultrient output into lillsborough Bay and thus help reduce the bay's over-
Wm'.rdance of Gracalaria.
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