714MODELING OF ESTUARINE WATER QUALITY
INTRODUCTIONEstuarine water quality is a term used to describe the quality
of characteristics of the water in estuaries. Although the term
implies quality in a physical-chemical sense, its use has been
extended to include also the acceptability of water in a socio-
economic sense. The term “water quality,” like environmental
quality and air quality, has to do with the quality of the water
or the environment wherever it is found and wherever it is
used or encountered. The high chemical and bacteriological
quality of the water supplies has become an almost matter-
of-fact part of any American’s life, but the quality of waters
in which man recreates has become of greater concern with
man’s awareness of degradation of the quality of the waters
around him.
Estuarine water quality has become a major focus of the
U.S. Environmental Protection Agency with passage of the
Water Quality Act of 1987 establishing the National Estuary
Program with the goal of identifying nationally significant estu-
aries, protecting and improving their water quality, and enhanc-
ing their living resources. The original four estuaries selected
in 1985 for study were Narragansett Bay in Rhode Island,
Long Island Sound in New York and Connecticut, Buzzards
Bay in Massachusetts, and Puget Sound in Washington. Within
a year, Albemarle-Pamlico Sounds in North Carolina and the
San Francisco Bay/Sacramento-San Jacinto Delta system in
California were added, and most recently Galveston Bay in
Texas, among others, has been added.
A thoroughly technical description of water quality
would require several volumes to cover the physical, chemi-
cal, and biological characteristics of water and how these
characteristics change in different environments, how they
interact, and how they influence the many ways water is
used by plants, animals, and especially man. This would be
true even though this article is limited to estuaries, which are
among the most complex natural systems known and which
feel the impact of man perhaps more than any other natural
aquatic system. Suffice it to say that estuarine water qual-
ity will be examined in a broad way only, and the reader is
referred to the books and articles cited in the bibliography
for further discussions on the topics covered herein.Use Context for Water QualityQuality of water may be discussed most usefully in the context
of water use. That is, for certain uses of water, whether they berecreation, drinking, navigation, or some other use, some level
of water quality is required or desired for that particular use.
Some uses, such as drinking, will require a much higher level
of water quality than will another use such as swimming, and
swimming may require a higher quality of water than naviga-
tion. The important point is that for desired uses of bodies or
areas of water, certain levels of water quality are desired, and
if the quality of the water desired or needed to support that
use is not present, the use may not be sustained. The concept
of use applies not only to man’s direct uses of the water, but
applies also to biological uses of bodies of water such as fish
spawning grounds, shrimp nursery areas, and so forth. Indeed,
the history of setting levels of desired water quality for par-
ticular uses has shown that following the setting of levels for
water quality for drinking and swimming, levels of water qual-
ity were set for protecting and enhancing the survival of fish
and other organisms in streams. Levels of dissolved oxygen
in streams, which are in state and federal water quality stan-
dards, are there to protect fish in those streams.
As uses for bodies of water become more numerous,
a competition for use of the water begins to develop. Uses
such as navigation, swimming, recreational fishing, fish and
shellfish nursery areas, and other uses are not uncommon
competing uses for a body of water. The quality of water
required to support each of these uses is different as noted
above, and because of this, some uses may or may not be
sustained, depending on which use is the most “beneficial”
of that particular body of water.
The Federal Water Quality Act of 1965 stated that
water quality standards were to be adopted by all the states
by June, 1967, and in preparation of these standard public
hearings were to be held to determine the desired uses of
all the waters of the state which were under federal jurisdic-
tion. Although many states had already determined uses of
their waters, particularly for streams, this was the first time
that a nation-wide effort was made to determine desired uses
of waters and to set water quality standards for them. The
hearings, the water quality standards developed, and the sub-
sequent implementation and enforcement of the standards
showed the very real problems which arise when competing
uses of the water resource become very strong and intense.
One or two particular uses become dominant, and the water
quality for a particular use is set to meet that use. Other uses
which require a higher level of water quality may or may not
be sustained, while levels of water quality required for other
uses may be more than adequately met.C013_006_r03.indd 714C013_006_r03.indd 714 11/18/2005 12:49:00 PM11/18/2005 12:49:00 PM