Hydrologic Unit (HUC8) Boundaries for Alaskan Watersheds

The United States is divided and sub-divided into successively smaller hydrologic units which are classified into four levels: regions, sub-regions, accounting units, and cataloging units. The hydrologic units are arranged or nested within each other, from the largest geographic area (regions) to the smallest geographic area (cataloging units). Each hydrologic unit is identified by a unique hydrologic unit code (HUC) consisting of two to eight digits based on the four levels of classification in the hydrologic unit system. A shapefile (or geodatabase) of watersheds for the state of Alaska and parts of western Canada was created by merging two datasets: the U.S. Watershed Boundary Dataset (WBD) and the Government of Canada's National Hydro Network (NHN). Since many rivers in Alaska are transboundary, the NHN data is necessary to capture their watersheds. The WBD data can be found at https://catalog.data.gov/dataset/usgs-national-watershed-boundary-dataset-wbd-downloadable-data-collection-national-geospatial- and the NHN data can be found here: https://open.canada.ca/data/en/dataset/a4b190fe-e090-4e6d-881e-b87956c07977. The included python script was used to subset and merge the two datasets into the single dataset, archived here.