 pesticides make up largest category on state s list of most toxic water pollutants according to the oregon department of environmental quality  deq  pesticides make up the largest category of persistent pollutants on a list  51 out of 140 that they released in june of this year the list is part of a longerterm project that the deq embarked on as a result of the passing of senate bill 737 which required the agency to develop a list of priority persistent bioaccumulative toxics priority persistent pollutant list that have a documented effect on human health wildlife and aquatic life deq s next step will involve identifying the sources of the pollutants and examining ways to reduce the amount that reaches oregon s waters  