Lake Nipissing is a productive water body and is highly valued as a recreational lake in Ontario. We report that the water chemistry of Lake Nipissing has not changed appreciably over the past 15 years. The small changes that were observed in Lake Nipissing have been reported for many smaller lakes throughout Ontario. These changes are primarily the result of regional impacts such as drought and acidification of watershed soils (causing changes in phosphorus concentrations), reduced deposition ofsulphur (resulting in lower lake sulphate concentrations), and the continued application of road salt. Despite the minimal changes reported throughout the main basin of Lake Nipissing, the current water quality of Cache and Callander Bays is significantly different, and is characterized by higher nutrient levels.