The Wetland Data is a combination of the MNRF Wetlands (detailed below) and the ELC data (from terrestrial field inventory). It has been further refined using the 2015 imagery as well as consultation from external partners and public.

The Wetland data class was previously known as Wetland Unit and the word "Unit" has been dropped from the name. The Wetland data class provides a spatial representation and attribute information for wetlands in Ontario. Not all wetlands have been identified and mapped. Active maintenance is ongoing throughout the province. The currency and accuracy of the spatial representation is variable and requires on-the-ground verification. Many attribute fields were added in 2012. Values will be added to these fields over time. Refer to the Wetland User Guide for details on using the data. Certain attributes identify which wetlands have been evaluated with the Ontario Wetland Evaluation System (OWES) and of those which ones have been designated as Provincially Significant wetlands (PSW). Previous to 2011 this data class contained only Evaluated Wetland data. In the spring of 2011 through the Wetland Consolidation project business areas were consulted to identify the best available existing MNR wetland data for each MNR district. The resulting data were added to this data class where it did not overlap existing Evaluated Wetland data. Sources for wetland data included Wetland Interim (OBM/NTS), Forest Resource Inventory (FRI), Southern Ontario Land Recourse Inventory System (SOLRIS) and MNR district data. Wetlands are lands that are seasonally or permanently flooded by shallow water as well as lands where the water table is close to the surface; in either case the presence of abundant water causes the formation of hydric (moist) soils and has favoured the dominance of either hydrophytic (water loving) or water tolerant plants. An individual spatial polygon represents a discrete wetland type. Values for wetland types are marsh, fen, swamp, bog, treed peatland, open water or unknown. Evaluated Wetlands are those identified and assessed using the technical criteria in the OWES manuals. An evaluation may be for either an Evaluated Wetland or an Evaluated Wetland Complex. Not all wetlands in Ontario have been evaluated. An Evaluated Wetland consists of one or more adjacent (contiguous) wetland polygons. An Evaluated Wetland Complex is a group of separated wetland polygons that have similar or complementary biological, social and/or hydrological functions, are located in close proximity, and are functionally linked (ecologically or hydrologically). An Evaluated Wetland Complex may contain adjacent wetland polygons but must comprise at least one separated wetland polygon. Wetlands that meet certain criteria through OWES are designated as PSWs. The wetland polygons are managed independently from other hydro data classes and may overlap waterbodies or other hydro data. Due to the changing landscape in the south western portion of the province and the vintage of available source data, MNR Aylmer district chose not to add some of the unevaluated wetland data from other sources to the existing Wetland Unit layer during the Wetland Consolidation Project of 2011. The Far North Hudson Bay Lowlands and surrounding area have been updated as of March 31 2013. Legislated or Legal Authority for Collection: The OWES evaluation information is collected to support the wetlands component of the Provincial Policy Statement. OWES data collection began in the early 1980's and will be on-going. Wetland evaluations are subject to changes as more information becomes available. Not all of the OWES information is stored in this layer. The complete OWES file including supporting material and field notes is kept at the MNR district office. Depending on any sensitivity or security issues associated with this information holding, some of the information may not be available for viewing or distribution.