The identification of an actual or potential toxicity problem in an aquatic system immediately poses several questions of practical importance.  Is the toxic agent still being added to the system? Where is the toxin coming from? Are the current filtration systems removing it? How soon will it be reduced to an acceptable level? How can it be removed faster? These questions in turn suggest equally important questions to the investigator.  What samples will give me the most information? What does the data from these samples mean in regard to the above questions? In order to make efficient use of analytical facilities an orderly approach to sampling is needed.  Mathematical modeling through the use of toxicokinetics can be used to maximize the efficiency of analysis of a toxic accident.  Strategies of sampling and interpretation of results will be discussed using the tools of toxicokinetic modeling.