SECTION 1 
INTRODUCTION 
EVALUATION OF BIOTOXICITY 
The Chester River is a tributary of the Chesapeake Bay, 
northeast of Kent Narrows. Historically, this estuarine part of 
the river has been rich in natural oyster bars; but, in the 
winter of 1974, a heavy mortality started upriver and moved over 
a period of years to bars in the lower reaches. The symptoms of 
this oyster mortality could not be attributed to any climatic or 
other natural phenomena that cause occasional oyster mortalities. 
A suspicion became plausible that something highly toxic to 
oysters had entered the upper river and had gradually worked its 
way downstream. A review of possible point sources of waste dis¬ 
charge into the Chester River system revealed the presence of the 
Chestertown sewage plant on Radcliffe Creek, the Campbell's Soup 
factory on Morgan Creek and the Tenneco plant that dumps its ef¬ 
fluent into a pond which eventually empties into Morgan Creek via 
a small creek. The investigations reported here were aimed at 
locating point sources of toxic materials, and stations were 
chosen to maximize the ability to identify the roles of these 
potential sources. 
PHTHALATE ESTERS AND RELATED CHEMICALS 
The State of Maryland has issued a permit to Tenneco, In¬ 
corporated, in Chestertown, Maryland, to discharge 10 ppm of 
total organic extractables into Morgan Creek which empties into 
the Chester River and, then, into Chesapeake Bay. This permit 
would appear to be reasonably conservative unless it conceals the 
basis for long-range harm. Such threatening possibilities do 
exist and will be considered in the present studies. The major 
problem is related to the question of whether the discharge is 
free to dilute itself in some innocuous way, or whether, on the 
contrary, the dilution processes are blocked and the basis for a 
toxic accumulation can be shown. In the latter case, the permit 
would have to be viewed as nonconservative and the ecological 
threats would have to be carefully considered and perhaps further 
constrained. 
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