Water Quality Criteria
W. W. TOWNE
JOHN W. WISEMAN
Basin Engineer, and Assistant Basin Engineer
Ohio-Tennessee Drainage Basins
Public Health Service
Department of Health, Education, and Welfare
Cincinnati, Ohio
It is not the purpose of this paper to present a compendium of
limiting concentrations of those substances which might be classified
as water pollutants. Rather, the authors will endeavor to present some
aspects of water quality criteria as related to water pollution control
programs, together with some problems associated with their development and application. Also, an attempt will be made to present some
of the philosophies relating to water pollution control in general, and
to water quality criteria in particular.
Water quality criteria are being used extensively by both the
regulatory agencies and the contributors of pollution. Much of the
recent water pollution control legislation requires the establishment of
criteria by regulatory agencies; use is made of criteria in administering
water pollution control programs; criteria are used in evaluating the
economics of sewage and waste treatment; and they are used as guides
to define pollution and to measure compliance with regulations. It is
certain that everyone engaged in almost any phase of waste treatment
or stream sanitation is aware of the difficulties encountered when trying
to reach agreement on a specific criterion. For example, should the
minimum dissolved oxygen content be four or five parts per million?
Or should the maximum permissible pH be 8.5 or 9.3? That much
thought and effort still remain to be expended, is further borne out
by the very fact that often the only uniformity among many water
quality criteria is the lack of uniformity.
It might be well to pause here for a moment and try to define what
is meant by the word "criteria." Every one has listened to discussions
and read papers in which the words "standards," "criteria," and "objectives" have been used extensively in defining a water quality. In many
instances they have been used synonymously, particularly "standard"
and "criteria."   Probably because the word "standard" may smack of
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