DEQ (formerly a part of OSDH) has been sampling, analyzing, and evaluating the safety of eating fish from Oklahoma’s lakes since 1978. As environmental practices have changed over time, contaminants of concern have also changed from cancer causing chlorinated pesticides like chlordane and DDT to metals like lead and mercury that affect the central nervous system. While DEQ still monitors fish at some legacy sites for chlorinated pesticides, in 2007 we began focusing on mercury levels in fish from Oklahoma’s lakes. DEQ currently monitors fish from 95 lakes throughout the state on a 5 year rotating basis for mercury. In 2007 and again in 2017 DEQ also sampled, tested, and evaluated the safety of eating fish from waters affected by the Tar Creek Superfund site in northeast Oklahoma.