Water chemistry data with geographic coordinates from lakes primarily in the Sudbury area of Ontario since 1981. Several lakes spread throughout the Sudbury acid rain damage zone had a natural buffering capacity protecting them from experiencing a severe drop in lake pH. Twenty-two of these lakes were selected to act as a local non-acidified reference set, for intermittent monitoring of baseline conditions in the region. Water chemistry sampling included several key monitoring components, including: * Acidity: pH, alkalinity, sulphate * Nutrients * Colour, clarity and organic matter * Metals and other ions