National Hydrographic Network (NHN) Watershed Boundary

National Hydrographic Network (NHN) data is produced and distributed by watershed, also known as NHN Work Units or NHN Index. Each NHN watershed boundary delineates the drainage area covered by an NHN dataset. There are more than 1382 basins covering the entire Canadian landmass. The NHN watersheds were created from the Water Survey of Canada Sub-Sub-Drainage Area (WSCSSDA) and Fundamental Drainage Areas (FDA) of the Atlas of Canada.
Note that NHN watersheds evolve over time. They are modified and refined when source data is replaced and updated, or when provincial source data is introduced into the data production process as part of NHN partnerships between federal and provincial/territorial agencies. Therefore, they no longer coincide exactly with the boundaries of WSCSSDAs and FDAs, so do not mix them up.