Water-resources subregion

What is Water-resources subregion?

Water-resources subregion meaning Subdivision of a water-resources region. The 21 water-resources regions of the United States are subdivided into 222 subregions. Each subregion includes that area drained by a river system, a reach of a river and its tributaries in that reach, a closed

 

reference: USGS – Water Basics Glossary