The Nyanza site is located in the central section of Ashland in a largely residential area. Chemical sludges generated by the dye manufacturing process were disposed of on an area of high ground referred to as, "Megunko Hill". Sludges containing large quantities of heavy metals (such as cadmium, chromium, lead, and mercury), aromatic amines (such as benzidine and 1-naphthylamine), and VOCs (such as 1,4-dichlorobenzene, trichloroethylene, and vinyl chloride) spilled and washed down the side of Megunko Hill to the wetlands below. Heavy metal sludges and organic solvents were disposed of in the lower industrial area in active lagoons or the underground vault. As a result, the groundwater beneath the site is highly contaminated with VOCs, SVOCs and metals. Anecdotal reports from the Ashland community provide evidence that children playing in the Megunko Hill area would often return home with blistered hands and discolored clothing.
In 1982, the U.S. Environmental Protection Agency placed the Nyanza site on the National Priority List. The Massachusetts Department of Environmental Protection (MDEP) restricted site access in 1982 by installing a partial fence. However, portions of the site were accessible to the public until the fence line was expanded in 1985.
In 1986, the Massachusetts Department of Public Health issued a fish advisory for the Sudbury River in Ashland to its confluence with the Assabet River in Concord, MA. The fish advisory warns residents to not eat any fish from the Sudbury River between Ashland and Concord due to mercury contamination.
This information is provided by the Community Assessment Program within the Department of Public Health.