This dataset consists of a set of polygons that represent the drainage areas of active discharge stations within the Southwestern Hudson Bay Drainage Area.

In partnership with the provinces, territories and other agencies, the Water Survey of Canada (WSC) operates a network of over 2600 active hydrometric gauges across the country. The NHS Basin Polygon dataset is compilation of datasets collected from a number of contributing agencies, including provinces, territories and other government departments. Environment and Climate Change Canada staff in a number of offices across the country is also responsible for the derivation of large parts of the dataset. Users should be aware that drainage areas derived from these polygons may differ from official drainage areas of hydrometric stations published by WSC.