iutin

ORIGINALL TO
ACTION

(COORDINATE WITH )


Executive O F'
Director 1.
Director A
Director s.
Director .P r A.
Attorney i
. e. ^ :- .
Dir. Employee Rel j
Dir. Field Maint.
.Dir. Finance_
Dir. Planning___
Dir. Real Estate
Dir. Regulatory
Dir. Res. Development
Dir. .Spec..Support
M. Gibbons
L. M. Blain
Chairman, Gov. Bd.
District Board
Basin Boards
Other.


A.


Director P..& R
Attorney
".. --
Dir. Employee Rel.
Dir. Field Maint.
Dir. Finance
Dir. Planning_
Dir. Real Estate
Dir. Regulation
Dir. Res: Development
Dir. -Spec. .Sippprt_


Other


SUSPENSE:
REMARKS:


~7C------




-. J .L.L UJ .- _


SUnited States Department of the Interior

GEOLOGICAL SURVEY

4710 Eisenhower Blvd.
Tampa, Florida 33614 /: .'

December 20, 1976'


Mr. Donald R. Feaster
Executive Director
SWFWMD
P. 0. Box 457--
Brooksville, Florida 33512

Dear Mr. Feaster:

Enclosed is the addendum statement which you requested be prepared for
inclusion in the recently prepared Potentiometric. change map for 169 to
1975 (WRI 76-80). Please consider this statement as a draft and you
should feel free to change it to fit your needs. Perhaps it could be
typed on your letterhead to avoid processinsthis UtatementthroIguq our
review system. I hope this statement clears up the questions that
developed at the last board meeting. If not, we stand ready to provide
; .-- additional explanation.
Sincerely yours,


John E. Moore
Chief, Southwest Florida
Subdistrict




cc: Conover
Bruce Kennedy
J. B. Butler
Zeb Palmer


JEM/aml


*1






( 0~ Draft
12/20/76
ADDENDUM TO WRI 76-80 EXPLANATION Moore, Ryder,
& Stewart


This map updates HA-440 by Stewart and others (1971) which depicted the

potentiometric surface in May 1969 and the change from January 1964 to
May 1969. HA-440 represented the best available change map of the district

when prepared, and has provided the district with useful water-resource
management information. This updated map was prepared because of an increase

in ground-water withdrawals during the past 6 years, and improvements in
monitoring network. Our hydrologic understanding is continually being

improved by increasing the number of observation wells in areas of large

ground-water withdrawals, by leveling observation wells, and by improved
general knowledge of the hydrogeology of the area. The map is based on

more than a thousand water-level measurements made in wells throughout the
District.

The reader is cautioned not to. overlay the two potentiometric surface maps

to obtain water-level changes. These changes in water level may not

correspond to values on the published change map because the intersection

of contours was only one type of control used to make the map. For example
areas of sparse water-level data the contour lines were smoothed and

generalized to conform with the known hydrogeology. In addition, consid-
erable hydrologic judgment was exercised in drawing the.change map.

The generalized contours show regional changes between May 1969 and May 1975.

Where detailed and quantitative information is needed, the user should
contact the U.S.Geological Survey office in Tampa.