Watershed Boundary Dataset; 12-Digit Watersheds Dissolved to 8-Digit Watersheds
This dataset is the digital hydrologic unit boundary layer for the 8-digit subwatershed boundaries 
for the conterminous United States. This dataset is intended to be used with the following two 
tabular dBase files:  https://water.usgs.gov/lookup/getspatial?ds573_tillage_lu92e and …