Mercury Johnson County Health Center is a superfund site located at 11875 South Sunset Dr, Olathe , KS 66061. The Environmental Protection Agency (EPA) identifies sites such as Mercury Johnson County Health Center because they pose or had once posed a potential risk to human health and/or the environment due to contamination by one or more hazardous wastes. Mercury Johnson County Health Center is currently registered as an Active superfund site by the EPA. However, it is not on the NPL (National Priorities List), which means the EPA does not consider it one of the nation's most hazardous waste sites.