Data integration issues

There has been no standardization of the storage of land-related information among the three single-tier, 11 upper-tier, and 93 lower-tier municipalities in the study area. Some municipalities use Geographic Information Systems to manage their data; others do not. Most smaller municipalities do not maintain zoning or by-law information in a format that is easy to integrate with other spatial data sets.

Digital mapping was obtained from the Central Lake Ontario Conservation Authority (CLOCA), the City of Hamilton, and the Region of Peel. In many cases, however, municipal information was available only through maps from Official Plans posted on municipal websites in Portable Document Format (PDF), which does not allow for data manipulation. Using various software tools, the lines were extracted from these documents, positioned spatially in the GIS, and assigned attributes based on the Official Plan designations.

Each natural heritage feature was identified by element type (wetland, woodland, ANSI, etc.) and status (e.g., provincially significant, locally significant, designated "Environmental Protection" in an Official Plan, etc.). Many of the natural heritage Greenlands features have multiple labels. For example, many ANSIs are also recognized as ESAs (and vice versa), while swamp wetlands may be mapped as woodlands, since swamps are often forested wetlands.

Most of the mapping was obtained at a scale of 1:10,000. The Provincial Government and most Conservation Authorities maintain data using the NRVIS mapping as a base, so there is usually reasonably good alignment of features. Difficulties arose when regions and municipalities used mapping at differing scales. Occasionally, the maps attached to Official Plans graphically presented features that were obviously generalizations of particular areas. Regional mapping may have been done at a much larger scale at a time before the widespread adoption of GIS. Rather than make assumptions about the specific features that may have been intended by these drawings, the illustrations were imported and located spatially with as little modification of boundaries as possible.

A related issue was the imperfect overlay of boundaries. Often, wetland, ANSI, or ESA boundaries would align closely, but not perfectly. In the analysis stage of this study, boundaries were not modified. For the final maps, however, small inconsistencies between boundaries were removed.