Provincial Watersheds, Historical

Note: This data has been replaced by the Ontario Watershed Boundaries (OWB). We are no longer updating this data. It is best suited for historical research and analysis. A watershed, also known as a catchment basin, includes all land that is drained by a watercourse and its tributaries. Watersheds are split into four categories: * primary * secondary * tertiary * quaternary These divisions are based on the federal framework originally known as the Water Resources Index Inventory Filing System. Ontario has 3 primary watersheds: * Great Lakes – St. Lawrence * Southwestern Hudson Bay * Nelson River Secondary watersheds are subdivisions of primary watersheds in Ontario. Most secondary divisions are either large river systems or groupings of small coastal streams. Tertiary watersheds are subdivisions of secondary watersheds in Ontario. Quaternary watersheds are subdivisions of tertiary watersheds. There are more than 1000 quaternary watersheds in Ontario.

Data and Resources

Additional Info

Field	Value
Last Updated	April 17, 2026, 19:08 (UTC)
Created	April 17, 2026, 19:08 (UTC)
contact_person	{"en": "Government of Ontario; Government of Ontario; Natural Resources and Forestry,,https://www.ontario.ca/feedback/contact-us?id=26930&nid=65620", "fr": "Gouvernement de l'Ontario; Gouvernement de l'Ontario; Natural Resources and Forestry,https://www.ontario.ca/fr/commentaires/pour-nous-joindre?id=26930&nid=65620"}
criticality_level	[]
data_dictionary	unknown,unknown,unknown
geographic_scope	[]
open_canada_collection	fgp
open_canada_date_published	2021-02-08 00:00:00
open_canada_keywords	{"en": ["environment", "environment and energy", "Environment and Natural Resources", "watershed", "Government information"], "fr-t-en": ["environnement", "environnement et énergie", "Environnement et ressources naturelles", "bassin versant", "Information gouvernementale"]}
open_canada_subject	["economics_and_industry"]
sensitivity_level	unrestricted
title_fr	Bassins hydrographiques provinciaux, historique
update_frequency	not_planned