A drainage basin is an area that drains all precipitation received as a runoff or base flow (groundwater sources) into a particular river or set of rivers. Canada’s major drainage regions are the Atlantic Ocean, Hudson Bay, Arctic Ocean, Pacific Ocean and Gulf of Mexico. Rivers are organized into networks, each with its own recharge area upstream, and drainage channel and mouth downstream. Networks are ordered from ocean to main river to secondary rivers to streams which correspond to ocean basins, river basins, sub-basins, sub-sub-basins, and so forth. The boundary of a watershed is called a drainage divide.

This map shows the five ocean drainage areas in Canada, the major river basins, the internal drainage areas and the diverted drainage areas. A drainage basin, sometimes called a watershed, is an area where all surface water shares the same drainage outlet. Surface water consists of the tiny trickles of water flowing on the surface of the earth that develop into larger streams and eventually combine to form a river. The boundary of a watershed is called a drainage divide.

Contained within the 5th Edition (1978 to 1995) of the National Atlas of Canada is a map that shows ocean drainage areas with component river basins and diversion areas. There are two tables: one gives data on drainage basin areas, the other on major drainage diversions.

This dataset consists of drainage basin boundaries for selected transboundary basins draining to the Gulf of Alaska in south-east Alaska. Basins were delineated to the basin outlet using a tidal datum of mean high water (MHW). The drainage basins are provided as polygons attributed with basin drainage area and as polylines attributed with the data source for each line segment, respectively.

This feature layer depicts the watershed boundaries of Canada and provides a detailed look at drainage areas and water flow for the entire land mass of Canada.

This map service references the Water Survey of Canada (WSC) data. The WSC has a 3-level hierarchy of drainage areas established in 1927 for the purpose of managing hydrometric stations (recording water levels or rates of flow). They are: Major Drainage Areas, Sub Drainage Areas and Sub-sub Drainage Areas.

This map service includes all three drainage area boundaries as well as the highest order boundary, the ocean drainage area.

Contained within the 2nd Edition (1915) of the Atlas of Canada is a map that shows the delineation of drainage basin. The total area drained is indicated in square miles for each basin, and drainage basins of the principal river systems of Canada, along with their areas. This includes the great oceanic drainage basins and the Hudson Bay basin. Only the Canadian drainage area is indicated on the map for basins that lie partly in the United States. There is also a table listing the lengths of major rivers in Canada and their principal tributaries.

Major Drainage Areas (MDA), as portrayed in this map, are part of the Standard Drainage Area Classification (SDAC) which was developed by Natural Resources Canada, in partnership with Statistics Canada, and Environment and Climate Change Canada. A drainage area, as opposed to a drainage basin or watershed, is a unit of statistical aggregation used for reporting purposes based upon drainage patterns and the underlying basins, delimited by a drainage divide. A drainage basin, sometimes called a watershed, is an area where all surface water shares the same drainage outlet. Surface water consists of water flowing on the surface of the earth that develops into larger streams and eventually combines to form a river. The 11 MDAs presented in this map comprise the uppermost level in the drainage area classification system which then divides into 164 sub-drainage areas, and then is further divided into 974 sub-sub-drainage areas. Relief was derived from the merging of two raster data sets, both resampled to 804 metre resolution: - High Resolution Digital Elevation Model (HRDEM) – CanElevation Series - Canadian Digital Elevation Model, 1945-2011 Further information on all these maps can be found on the Atlas of Canada web site atlas.gc.ca.

A drainage basin is an area that drains all precipitation received as a runoff or base flow (groundwater sources) into a particular river or set of rivers. Canada’s major drainage regions are the Atlantic Ocean, Hudson Bay, Arctic Ocean, Pacific Ocean and Gulf of Mexico. Rivers are organized into networks, each with its own recharge area upstream, and drainage channel and mouth downstream. Networks are ordered from ocean to main river to secondary rivers to streams which correspond to ocean basins, river basins, sub-basins, sub-sub-basins, and so forth. The boundary of a watershed is called a drainage divide.

A drainage basin is the area that drains all precipitation into a river or stream system into a common outlet such as a lake or sea. There are two main river basins in Nunavut: the Thelon River flows into Hudson Bay and the Back River empties into the Arctic Ocean. Most of Nunavut’s area is not drained through large rivers; instead the water flows directly to the ocean through small rivers and streams.

Contained within the 3rd Edition (1957) of the Atlas of Canada is a map that shows drainage basins and river flow. The delimited drainage basins cover all Canadian land and fresh water areas. The areas of many drainage basins are written on the map. These areas do not include diversions (thus, the Albany does not include the area of its basin diverted to the St. Lawrence system). As well, the Interior Drainage class is not considered tributary and the areas it covers are not included in the total figure for the Hudson Bay Basin. At 23 selected gauging stations the average discharge in thousands of cubic feet per second is indicated along with the recorded maximum, minimum and average discharge. The data on river flow is derived from gauging station records for periods that vary considerably from river to river. For many rivers accurate data is not available. Two graphs are included, one denoting the areas of principal lakes, and the second showing the lengths of principal rivers.

Contained within the 3rd Edition (1957) of the Atlas of Canada is a map that shows drainage basins and river flow. The delimited drainage basins cover all Canadian land and fresh water areas. The areas of many drainage basins are written on the map. These areas do not include diversions (thus, the Albany does not include the area of its basin diverted to the St. Lawrence system). As well, the Interior Drainage class is not considered tributary and the areas it covers are not included in the total figure for the Hudson Bay Basin. At 23 selected gauging stations the average discharge in thousands of cubic feet per second is indicated along with the recorded maximum, minimum and average discharge. The data on river flow is derived from gauging station records for periods that vary considerably from river to river. For many rivers accurate data is not available. Two graphs are included, one denoting the areas of principal lakes, and the second showing the lengths of principal rivers.

The polygons in this layer delineate headwater-to-saltwater drainage basins of the Southeast Alaska Drainage Basin (SEAKDB) which includes the Alaska portion of the perhumid coastal temperate rainforest (PCTR). All geoprocessing was performed using ESRI ArcGIS version 9.3.1 or 10.x. This data set was derived from 4 main sources:1) The United States Geological Survey's (USGS) digital Watershed Boundary Dataset (WBD). The boundaries in the WBD were mapped at the subwatershed (12-digit) 6th level ("HUC12"). Citation for this data source: Coordinated effort between the United States Department of Agriculture-Natural Resources Conservation Service (USDA-NRCS), the United States Geological Survey (USGS), and the Environmental Protection Agency (EPA). The Watershed Boundary Dataset (WBD) was created from a variety of sources from each state and aggregated into a standard national layer for use in strategic planning and accountability. Watershed Boundary Dataset for Alaska. Available URL: "http://datagateway.nrcs.usda.gov" [Accessed March 9, 2012]. 2)British Columbia's Corporate Watershed Base (CWB) Freshwater Atlas Watershed Groups digital dataset (FWWTRSHDGR), downloaded from GeoBC on 3/14/2012. This site has since been replaced by DataBC. Freshwater Atlas documentation can be downloaded from ftp://ftp.geobc.gov.bc.ca/pub/outgoing/FreshWaterAtlasDocuments/FWAv1.3-SDE.WarehouseModelSpecification.rev3.doc. Metadata details can be found at https://apps.gov.bc.ca/pub/geometadata/metadataDetail.do. 3) At the USGS HUC8 (8-digit) and Canada NHN 4-digit drainage levels (CAN4), trans US-Canada watershed boundaries are consistent with the US-Canada hydrographic data harmonization revisions made as of 11/29/2012 (http://datagateway.nrcs.usda.gov). See nhd.usgs.gov/Canada-US_Hydro_Harmonization.pdf for more information on this project. 4) At drainage levels finer than HUC8/CAN4, screen digitizing was used to match up watershed boundaries crossing the Canada-US boundary. The best of availble source material was used for digitizing, including contours generated from USGS 2-arc second (~50 meter) NED DEMS, SPOT 20-meter DEMs, Environment Yukon 30-meter DEMs, and BC TRIM 25-meter DEMs; Tongass National Forest color and black and white orthophotography, satellite imagery obtained from the US Forest Service, Google Earth satillite imagery, and 1:63,360 USGS topographic maps. After a seamless watershed coverage was created using the above 4 sources, subbasins were "aggregated up" (i.e., merged) to depict entire headwater to saltwater drainages. Watersheds were clipped using an Identity operation to an approximate mean high water (MHW) shoreline where NOAA National Shoreline data (through 2011) existed. Where NOAA MHW data was absent, the high water line is represented using other shoreline digital data sources from the US Forest Service (feature class "Intertidal_PL", description=LND) and the US National Park Service (shapefile "HHTide"), and the US National Hydrography Dataset (NHD). In addition, heads up digitizing was necessary where shore recources were absent, of poor quality, or where the previously listed sources needed to be edge-matched. Data sources for digitizing include the US DEMs and orthophotos listed above under #4, 30-meter ASTER DEMs, Google Earth imagery, and US Forest Service 1:15,840 aerial photography stereo-pairs, All multi-part features were converted to single-part. Island polygons less than 10 hectares were deleted. All islands less than 100 hectares are considered a single watershed. If islands less than 100 hectares were mapped in the WBD as more than one watershed, the boundaries were merged.UPDATE, 5/11/2017: Portions of the Alsek drainage boundary were edited using updated digital boundaries obtained from Janet Curran at the USGS. The updates were a part of a flood frequency report (USGS SIR 2016-5024) and StreamStats project.

Contained within the 4th Edition (1974) of the Atlas of Canada is a map that shows drainage basins as well as major lakes and diversions. The map displays the ocean drainage areas along with component river basins and diversion areas for the Arctic, Pacific, Hudson Bay and Atlantic drainage areas.

Contained within the Atlas of Canada 8.5x11 series maps is a map which was created as a joint effort by The Atlas of Canada, The National Institute of Statistics, Geography and Informatics, Mexico and the National Atlas of the United States under the sponsorship of the commission for environmental cooperation. The map shows the major North American drainage basins, or wateresheds, which drain into the Atlantic Ocean, Hudson Bay, the Arctic Ocean, the Pacific Ocean, the gulf of Mexico and teh Caribbean Sea. Each watershed is shown in its own colour, with subdivisions shown in tonal variations. Areas of internal drainage, which lack outlets to the sea, are shown in grey.

The Water Survey of Canada (WSC) is the national authority responsible for the collection, interpretation and dissemination of standardized water resource data and information in Canada. In partnership with the provinces, territories and other agencies, WSC operates over 2800 active hydrometric gauges across the country. WSC maintains and provides real-time and historic hydrometric data for some 8000 active and discontinued stations. This dataset consists of a set of polygons that represent the drainage areas of both active and discontinued discharge stations. Users are encouraged to report any errors using the “Contact Us” webpage at: https://weather.gc.ca/mainmenu/contact_us_e.html?site=water

Contained within the 2nd Edition (1915) of the Atlas of Canada is a map that shows the delineation of drainage basin. The total area drained is indicated in square miles for each basin, and drainage basins of the principal river systems of Canada, along with their areas. This includes the great oceanic drainage basins and the Hudson Bay basin. Only the Canadian drainage area is indicated on the map for basins that lie partly in the United States. There is also a table listing the lengths of major rivers in Canada and their principal tributaries.

Contained within the 5th Edition (1978 to 1995) of the National Atlas of Canada is a map that shows ocean drainage areas with component river basins and diversion areas. There are two tables: one gives data on drainage basin areas, the other on major drainage diversions.

Contained within the 1st Edition (1906) of the Atlas of Canada is a map that shows the delineation of drainage basins. The geographic extent of each drainage basin is delineated and the total area drained for each basin is provided in square miles. This includes the great oceanic drainage basin and the Hudson Bay basin. Only the Canadian drainage area is indicated on the map for basins that lie partly in the United States. There is also a table listing the lengths of major rivers of Canada and their principal tributaries.

The Ontario Watershed Boundaries (OWB) collection represents the authoritative watershed boundaries for Ontario. The data is based on a framework similar to the Atlas of Canada Fundamental Drainage Areas and the United States Watershed Boundary Dataset, however it adopts a more stringent scientific approach to watershed delineation. The Ontario Watershed Boundaries (OWB) collection includes five data classes:OWB Main (OWB) (Download: Shapefile | File Geodatabase | Open Data Service | QGIS Layer )all watershed levels from primary to quaternary, and level 5 and 6 watersheds for select areas of the province;OWB Primary (OWBPRIM) (Download: SHP | FGDB | ODS | QLR-Diverted Flow | QLR-Natural Flow)all primary watersheds or major drainage areas (WSCMDA) in the Canadian classification;OWB Secondary (OWBSEC) (Download: SHP | FGDB | ODS | QLR*)all secondary watersheds or sub drainage areas (WSCSDA);OWB Tertiary (OWBTERT) (Download: SHP | FGDB | ODS | QLR*)all tertiary watersheds or sub-sub drainage areas (WSCSSDA);OWB Quaternary (OWBQUAT) (Download: SHP | FGDB | ODS | QLR)all quaternary watersheds or 6-digit drainage areas (WSC6).*Display issues in QGIS are currently being investigated for these services. See the RSS feed below for details.IMPORTANT NOTE: The OWB data replaces the following data classes:Provincial Watersheds, HistoricalAdditional DocumentationUser Guide for Ontario Watershed Boundaries (Word)Watershed Delineation Principles and Guidelines for Ontario (Word) Atlas of Canada 1,000,000 National Frameworks Data, Hydrology - Fundamental Drainage Areas United States Geological Survey Watershed Boundary Dataset (Website)

Status Completed: Production of the data has been completed

Maintenance and Update Frequency Irregular: data is updated in intervals that are uneven in duration - usually after the completion of major updates to source data (e.g. OIH), but could also include spot updates and expansion of the dataset over time based on user needs. RSS FeedFollow our feed to get the latest announcements and developments concerning our watersheds. Visit our feed at the bottom of our ArcGIS Online OWB page.

Contact Ontario Ministry of Natural Resources - Geospatial Ontario, geospatial@ontario.ca

A drainage basin is an area that drains all precipitation received as a runoff or base flow (groundwater sources) into a particular river or set of rivers. Canada’s major drainage regions are the Atlantic Ocean, Hudson Bay, Arctic Ocean, Pacific Ocean, and Gulf of Mexico. A lake can be defined as any inland body of water, usually fresh water, larger than a pool or pond. Canada is covered by as many as two million lakes. The largest set of lakes, the Great Lakes, straddle the Canada-US boundary and contain 18% of the world’s fresh water in lakes. Most Canadian rivers have developed since the last ice age. Almost 75% of the Canadian landmass contains water that drains northward into either the Arctic Ocean or into Hudson and James bays.