MEMORANDUM May 22, 17'
TO: Dale H. Twachtmann, Executive Director
FROM: William D. Courser, Biologist
Re: Florida Power and Light Proposal to Divert Water from the Little Manatee River
Since receipt of the Florida Power and Light Company's (FPL) summary of application to
divert water from the Little Manatee River (dated 28 March 1972), the company has
changed the location of their proposed reservoir. We have reviewed their original summary,
explored the site detailed in this report on 20 April with Tim Varney of the Hillsborough
County Planning Commission, and accompanied Dr. Larry Brown on his initial survey of
the newly proposed reservoir area (Willow site) on 27 April Dr. Brown has been retained
by FPL to study the environmental impact of the proposed reservoir.
The current site, entirely within Manatee County, is, comparatively speaking, of less quality
than the area (Parish site) outlined in their letter. The Parish site is predominantly established
second growth pine flatwoods with interspersed marshes and cypress heads. A small amount of
cultivated land is present as well as about 500 acres of hardwood hammock along creeks and
streams in the northern portion of the area. Their cursory assessment of the impact of the
reservoir on this area is accurate but not detailed. Several problem areas have been overlooked
These problems will be discussed below.
The Willow site for the reservoir is predominantly improved and native pastureland with some
pine flatwoods. Along the eastern edge of the property (but not in the area to be flooded by
the reservoir) a small amount of sand pine scrub association is found. This habitat type is
becoming less numerous in Florida as it occurs in the soil type ideally suited for citrus groves.
Every effort should be made to preserve this association. The Willow site is an area better
suited for a reservoir if a reservoir must be built.
Dr. Brown has only been retained to study the Willow area over a period of two to four weeks.
That amount of time is not adequate to get a detailed environmental inventory especially of
migratory animals and fall-winter flowering plants. FPL should consider a more thorough
biological investigation of the proposed site.
In their examinations of the impact that might arise from the construction of a reservoir (this
discussion would apply at either site), several points have been overlooked. The environmental
services team has posed several questions which should be thoroughly investigated by FPL before
plans are completed for the reservoir.
Will the bed of the reservoir hold water? Is the pool above the potentiometric surface? The
geology and hydrology of the area should be sufficiently understood to allow best placement of
the cooling lake.
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To: Dale H. Twachtmann
May 22, 1972
What safeguards have been taken to prevent dike breakage? Is there a channelled overflow
to ease dike pressure when rainfall will increase the chance of spills during the rainy season?
Have evapotranspiration rates been figured into their calculations on cooling needs? -A net
loss of 6-7,000 acre feet of water per year can occur from a 6,500 acre reservoir.
No mention is made of accelerated entrophication problems that might occur when the reser-
voir is established. Incorporation of a littoral zone into the reservoir design would definitely
enhance recreational values of the pool.
What emission control -standards would be employed at the plant site ? Unless strict emission
controls are adherred to, the meteorological production of local smog might result.
The Game and Fresh Water Fish Commission should be consulted with as to the impact created
on the Little Manatee's fishery resources when twenty percent of the river's flow is diverted.
What effect will the decrease in the amount of fresh water flowing into the Gulf have on the
Cockroach Bay estuary? This is perhaps the most important aspect of the environmental impact
especially since Cockroach Bay has some of the best quality water in Tampa Bay and has been
proposed as an aquatic preserve area. An increase in the salinity of the estuary will surely
result. Will this increase reach the threshold necessary for Red Tide algal blooms? Will the
salinity have adverse effects on the mangroves perhaps encouraging invasion of the Red
Mangroves by an isopod that destroys their prop roots? These and other effects a salinity
c change can produce in an estuary can only be theorized. An environmental assessment of the
estuary before the project and an assessment of the environmental impact is a necessity before
such a project is undertaken.