I have been involved with several enviornmental studies for EPA registration of several new chemical products. EPA registration of a chemical for use in aquatic or terrestrial environments is a very lenghty and involved process which includes chemical, biological and environmental testing. Tests involve analyses of the various impacts from drift, runoff, and direct application and how the various components the aquatic food chain are affected. They (producer and regulatory agency) try to consider many of the possible fates including degredation products that the chemical formulation might have once it is introduced into the ecosystem. Slightly different formulations of basically the same chemical could easily "behave" differently in the widely different biological communities living in a pond. Chemical half life and its bioaccumulative nature are other very important aspects that are usually currrently tested for each product registration.
Thus, using apparently the same herbicide- pesticide outside of its intended use can be playing enviornmental roulette. I personally would not do that if I was eating the fish from that water body. Since many ponds are occassionally used for swimming, playing in this water and exposing delicate and permable mucous or body tissue membranes to water randomly laced with herbicides or pesticides that have been applied outside of label recommendations is not my idea of good common sense.
