The percent natural land cover grid for Ontario was developed by the Ontario Ministry of Natural Resources' Geomatics Service Centre for the Great Lakes Conservation Blueprint for Biodiversity using the 28-class Ontario land cover data. A comparable natural land cover grid for New York was developed by The Nature Conservancy using New York's GAP land cover data and the same methods as applied in southern Ontario. These grids were used to calculate the percent natural cover in each quaternary watershed (Ontario) and 11-digit HUC watershed (New York), shown in the inset map.