Wetland Unit

Retirement note: please note that this dataset has been revised and replaced by "Wetland", which is available from the Land Information Ontario (LIO) Warehouse.

The Wetland Unit data class provides the spatial representation and basic information for all wetlands in Ontario. The attributes identify which wetlands have been evaluated and of those which ones have been designated as Provincially Significant.

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 moist soils and favours the dominance of water tolerant plants.

A Wetland Unit is an individual spatial polygon representing a discrete wetland type. The current wetland types are marsh, fen, swamp, bog, open water or unknown.

Evaluated Wetlands are those identified and assessed using the technical criteria in the Ontario Wetland Evaluation System (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 Units. An Evaluated Wetland Complex is a group of separated Wetland Units 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 Units but must comprise at least one separated Wetland Unit. Wetlands that meet certain criteria through OWES are designated as Provincially Significant.

The Wetland Unit data are managed independently from other hydro data classes and may overlap waterbodies or other hydro data.

In the MNR Alymer District, due to the changing landscape in the south western portion of the province and the vintage of available source data the district chose not to add some of the unevaluated wetland data from the other sources to the existing Wetland Unit Layer. In the Far North Hudson Bay Lowlands and surrounding area some of the wetlands were not available and will be populated through a project with NRCan over the course of the year.

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.

Supplementary tables can be used and are available for download from the additional documentation section. This layer is part of what was known as the OMNR Fundamental Dataset.