Environmentally Significant Areas (ESAs) are natural areas that have been largely identified as significant and worthy of protection based on three criteria (ecology, hydrology, and geology). Municipalities generally use ESAs as the policy by means to protect natural areas to meet their requirements under the Provincial Planning Act and Provincial Policy Statement. In the Niagara Watershed (except for within the City of Hamilton) there is no definitive and spatially discrete inventory for natural heritage features with official ESA status, however there are several reports and documents with collections of natural heritage features that alude to ESA status. This feature class is a compilation of these available sources and forms an inventory for the Niagara Watershed of natural areas that are potential ESAs.