. MEMORANDUM August 23, i:72
j TO: Donald R. Feaster, Director, Water Resources Division
FROM: James A. Mann, Chief, Permits Department
RE: Proposed Diversion of Water from Little Manatee River by Florida
Power and Light Company
it apper% s that Department of Natural Resources made on error by not setting an upper
limit on the amount of water Florida Power and Light will be permitted to divert from the
Little Manatee. As I understand the wording of DNR's action all flow in excess of 40
cfs (cubic feet per second) may be diverted by FP&L.
The average of the monthly minimum flows at the diversion site is 35.6 cfs. The maximum,
minimum and median of the monthly minimum flows at this location are III cfs, 8.85 cfs,
and 24.2 cfs respectively. The values of monthly minimum flow for ten months is less than
For oa, average of eight months each year (1940-71) the monthly mean flow was greater
than 40 cfs. Therefore, for an average of eight months each year during this period
FP&L could have diverted all water above 40 cfs. Conversely, for an average of four
months each year during this period the monthly mean flow was less than 40 cfs and there
could have been no diversion. A flow of 40 cfs at the diversion site is equaled or exceeded
53 percent of the time.
The long term average flow at the diversion site is 168 cfs. Forty cubic feet per second
Is 24 percent of this value. Therefore, the amount of flow that may be diverted is 128 cfs
or 76 percent of the long term average flow. One hundred twenty-eight cubic feet per
second equals 83 mgd (million gallons per day). This amount may be diverted providing
sufficient pumping capacity is available. An earlier proposal of FP&L at a downstream
diversion site was for a pumping capacity of 300 cfs to divert 75 cfs or 48 mgd. This 48
nrgd diversion was to supply a 3400 mw Megaa watt) plant which was double the plant site
now being proposed.
SThe attached hydrograph of monthly mean flow (from Brown and Root's report) illustrates
rather vividly the diversion of all water in excess of 40 cfs.
^ The average minimum flows at the diversion site are based on 20 years of record prior to
All flow quantities are based upon gaged record at U.S. Highway 301 and have been adjusted
for the decreased drainage area at the diversion site. The adjustment factor is 0.925.
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