Suspended Solids Standards for the
Protection of Aquatic Organisms
JOHN CAIRNS, JR., Professor
Department of Zoology
University of Kansas *
Lawrence, Kansas 66045
INTRODUCTION
White (1), a professor of history at the University of California, notes that
many of the calls to action in our current ecological crisis are too partial, palliative or negative. To quote several sentences from his interesting article, "The
simplest solution to any suspect change is, of course, to stop it, or, better yet, to
revert to a romanticized past: make those ugly gasoline stations look like Anne
Hathaway's cottage or (in the Far West) like ghost-town saloons. The "wilderness
area" mentality invariably advocates deep-freezing an ecology, whether San
Gimignano or the High Siena, as it was before the first Kleenex was dropped. But
neither atavism nor prettification will cope with the ecological crisis of our
time."
It is also evident to thoughtful people that no species from diatoms to man
can avoid interacting with the environment and changing it in various ways which
will then spread through the entire ecosystem as the ripples from a thrown stone
spread over the surface of a pond. So our choice is not whether we should or
shouldn't interact with out environment but rather how and toward what end. It is
readily apparent to even the most casual observer that mankinds power resulting
from science and technology has produced a variety of "ecological backlashes.
As a result, our belief in man's transcendence of and mastery over nature is now
being replaced by recognition that in order to achieve a harmonious relationship
with our environment we must adjust our activities to avoid damage to the ecological systems upon which we depend. It is within this context that I intend to
discuss suspended solid standards for the protection of aquatic organisms.
NATURAL VARIATION IN SUSPENDED SOLIDS LOAD
The concentration of suspended sediment in streams is influenced by such
factors as topography, geology, soil conditions, intensity and duration of rainfall,
and the type and amount of vegetation in the drainage basin. Suspended solids
concentrations may vary quite dramatically. For example, McCarthy and
Keighton( 2) report that sediment concentrations for the Delaware River at Trenton,
New Jersey, have ranged from one mg/1 to 4,100 mg/1. The daily loads of suspended sediment in the Delaware River at Trenton Thave ranged" from 0.5 tons
per day to one million tons per day (on August 20, 1955). In the six years from
October 1949 to September 1955 a total of 6. 7 million tons of suspended sediment
was carried by the Delaware River past Trenton; 26 percent of this was in the flood
caused by hurricane Diane. Most flowing waters have considerable variation in
the suspended solid concentration from day to day. In addition there may be substantial differences in suspended solid concentrations in different stretches of a
stream. This may occur where material carried as bed load is thrown into suspension at a narrows or falls where the velocity increases.
*   Address after September 2,   1968 -• Department of Biology,   Virginia Polytechnic
Institute, Blacksourg, Virginia 24061
-'16  -