Title: Draft - Water Supply Needs and Sources Assessment - Appendix G - September 22, 1993, Leter From Peter F. Anderson, P.E., Geothrans, Inc.
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Permanent Link: http://ufdc.ufl.edu/WL00004583/00001
 Material Information
Title: Draft - Water Supply Needs and Sources Assessment - Appendix G - September 22, 1993, Leter From Peter F. Anderson, P.E., Geothrans, Inc.
Physical Description: Book
Language: English
Spatial Coverage: North America -- United States of America -- Florida
Abstract: Jake Varn Collection - Draft - Water Supply Needs and Sources Assessment - Appendix G - September 22, 1993, Leter From Peter F. Anderson, P.E., Geotrans, Inc. (JDV Box 90)
General Note: Box 24, Folder 2 ( Emerging Issues and Conflicts - 1976-1994 ), Item 10
Funding: Digitized by the Legal Technology Institute in the Levin College of Law at the University of Florida.
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Bibliographic ID: WL00004583
Volume ID: VID00001
Source Institution: Levin College of Law, University of Florida
Holding Location: Levin College of Law, University of Florida
Rights Management: All rights reserved by the source institution and holding location.

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SEPTEMBER 22, 1993

GeTrans, inc.

46050 Manekin Plaza Suite 100 Sterling. Virginia 20166
703 .444 7000

September 22, 1993

Ms. Barbara Vergara
St. Johns River Water Management District
P.O. Box 1429
Palatka, FL 32178-1429

Reference: SJRWMD Needs and Sources Project
Contract No. 93D277
GeoTrans Project No: 7684-000

Dear Barbara:

Thank you for the opportunity to participate in the Needs
and Sources criteria consultant group, in particular, the panel
discussions last week. I enjoyed the exchange of ideas with a
very talented and diverse group of individuals. I look forward to
continued involvement with the group and SJRWMD.

I have a-few observations and comments that occurred to me
either as the session was ending or on my trip back to Virginia.
First, I believe that there was some confusion on the part of the
audience and even some of the panel members on the intent of the
Needs and Sources project. My understanding is that it is an
assessment of stressed areas. The Needs and Sources project will:
1) define water use needs to the year 2010, 2) describe projected
impacts of water use needs, 3) define thresholds of acceptability,
and 4) delineate areas of inadequate water resources to meet
demands. In particular, we were asked to comment on methods to
define thresholds (item 3). We are not attempting to define best
management practices or set new policy. I believe that too much
time was spent on philosophical discussions on policy and not
enough time on the very specific task at hand. Perhaps the next
session will focus more directly on delineation of thresholds.

Secondly, along those lines, I was a bit surprised to hear
Jake Varn wrap up the discussion by saying, in effect, that the
group would focus on determining a safe yield at the next session.
The definition of safe yield is "the amount of water which can be
withdrawn from a groundwater basin without producing an undesired
result" (Todd, 1959). This is usually a very elusive number
because it changes with season, location of stress, and in the
determination of what is an undesirable effect. Rather than

Ms. Barbara Vergara

attempting this monumental task for the Needs and Sources project,
the SJRWMD has correctly, in my view, chosen to determine if
projected pumpage exceeds the indicators of safe yield, that is,
has any undesirable effects in particular geographic areas.
Because the SJRWMD has already defined potential indicators of
safe yield exceedence, it is now up to the consultant group and
other parties to agree with or revise them, or propose new
indicators. We will not determine a safe yield.

Finally,.although I agree that these criteria need not be
uniform throughout the SJRWMD, I'm not sure that it is necessary
spend the effort to divide the SJRWMD into sub-basins for the
purposes of this assessment. The particular sub-division that is
chosen may not fit the needs of all criteria. A hydrogeologically
reasonable attempt at subdividing has already been accomplished by
defining boundaries and model extents for the various modeling

I hope these comments are useful. I look forward to
reviewing the next set of evaluation factors and continued
involvement with the consulting group and SJRWMD.


Peter F. Andersen, P.E.
Vice President
Principal Engineer



September 22, 1993

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