Sylvester is a superfund site located at Gilson Rd, Nashua, NH 03062. The Environmental Protection Agency (EPA) identifies sites such as Sylvester 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. Sylvester is currently registered as an Active NPL superfund site by the EPA. Because it is on the NPL (National Priorities List), Sylvester is considered one of the worst hazardous waste sites identified by the EPA.