Section Two
BIOLOGICAL: INHIBITION AND TOXICITY
5    WHOLE EFFLUENT TOXICITY IN STORMWATER:
COMMONLY IDENTIFIED TOXICANTS AND
COMPOUNDING FACTORS
Micheal B. Copenhaver, Project Manager
Douglas J. Fort, Vice President
Enos L. Stover, President
John K. Delphon, Laboratory Manager
Thomas W. Gorman, Laboratory Supervisor
THE STOVER GROUP
P.O. Box 2056
Stillwater, Oklahoma 74076
INTRODUCTION
Approaches used today to regulate the discharge of contaminants in stormwater to the environment are similar to those used by National Pollutant Discharge Elimination System (NPDES)
permits for wastewater effluent discharge. Stormwater regulations require the development and
implementation of a specific management plan for controlling contaminant release, as well as
specific water quality monitoring which includes Whole Effluent Toxicity testing. Unlike wastewater effluents, many facilities discharging stormwater do not provide pretreatment prior to release. Thus, the number of Whole Effluent Toxicity problems emanating from stormwater are escalating, particularly in the midwestern United States.
Stormwaters from two industrial facilities were studied to determine the cause(s) and source(s)
of aquatic toxicity, and provide recommendations on practical remedial actions needed to abate
Whole Effluent Toxicity. The Case Study 1 facility is a mirror manufacturing company, and the
Case Study 2 facility manufactures wire. Results from both facilities' stormwater toxicity tests
indicated that the runoff from the respective collection points induced acute toxicity to both
Daphnia pulex and Pimephales promelas. Both cases were superficially straightforward in terms
of identifying the causes of toxicity. The Toxicity Identification Evaluation (TIE) studies, however, were complicated by the physical/chemical characteristics typical of the stormwater encountered in the midwest region. First, virgin rainwater is extremely low in ionic strength containing virtually no hardness (CaC03) and second, the pH of the regional stormwater is typically
acidic. Thus, the nature of the stormwater itself poses problems in terms of Whole Effluent Toxicity. These stormwater chemical characteristics were the principal issues in the two studies. The
results from the associated investigations from Case Study 1 and Case Study 2 are presented
herein.
INVESTIGATIVE PROGRAM
Approach
Stormwater in the midwestern United States may be ionically imbalanced or deficient in critical ions necessary to support a homeostatic environment for aquatic organisms, particularly the
52nd Purdue Industrial Waste Conference Proceedings, 1997. Ann Arbor Press, Chelsea. Michigan 48118. Printed in
U.S.A.
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