Yellowstone River Basin study unit boundary, National Water-Quality Assessment Program, scale 1:100,000, Montana, North Dakota, and Wyoming

As part of the U.S. Geological Survey's National Water-Quality
Assessment Program, an investigation of the Yellowstone River Basin
study unit is being conducted to document status and trends in
surface- and ground-water quality. Efficient quantification of a
variety of environmental and geographic characteristics of the study
unit requires a digital map of the study-unit boundary that may be
processed, together with other digital thematic maps (such as geology
or land use), in a geographic information system (GIS). Digital
boundary data for the Yellowstone River Basin study unit are included
in this data release. The boundary follows drainage divides that were
identified chiefly using 1:100,000-scale (50 m accuracy) hypsography.