Watershed, Secondary

Coordinate system: 4269 - "NAD83"


Revision Note: Please note that this dataset has been revised and is available from the Land Information Ontario (LIO) Warehouse.

A secondary watershed is a polygon feature that identifies one of the thirty subdivisions of the primary watershed divisions which comprise the entire Province of Ontario. Most secondary divisions are either large river systems or groupings of small coastal streams. A watershed, also known as a catchment basin or area, includes all of the land that is drained by a watercourse and its tributaries. These divisions are based on the federal 'Drainage Area' reporting framework originally known as the Water Resources Index Inventory Filing System (WRIIF).

'The Water Survey of Canada (or, as it was known then, the Department of the Interior, Dominion Water Power Branch) first developed, in 1922, a Water Resources Index Inventory as a convenient and logical system for recording and filing water resources data. It was designed for the storage of such information as the location of waterpower sites, waterpower developments, storage reservoirs, stream measurement stations, and meteorological stations. The Water Survey of Canada delineations involved the division, sub-division and sub-sub-division of Canada into suitably sized areas based on the drainage, for administrative purposes. Although the boundaries are based on drainage, the intent was to include all of Canada's land mass and waters within this drainage area hierarchy to facilitate the identification of hydrometeorological sites. Therefore, the WSC drainage areas do not necessarily define individual river basins, but can represent intervening areas along the coast or include islands.' (National Scale Frameworks HYDROLOGY Version 5.0, NRCan, 2003)

ABOUT THIS RELEASE: These boundaries have been created based on the recent Version 2 Provincial DEM and Enhanced Flow Direction products released 2006-2008. The generation of the boundaries also involved some enhanced interpolation and smoothing techniques to produce a final product that is consistent with the current regional hydrology available for Ontario. Watershed naming conventions have also been revised to be more closely in line with Federal names where appropriate.

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