Drainage-area boundaries for selected sampling stations, scale 1:100,000, Yellowstone River Basin, 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. Surface-water samples are collected from streams or lakes at
specific sampling stations. Water-quality characteristics at each station are
influenced by the natural and cultural characteristics of the drainage area
upstream from the sampling station. Efficient quantification of the drainage
area characteristics requires a digital map of the drainage area boundary that
may be processed, together with other digital thematic maps (such as geology
or land use), in a geographic information system (GIS). Digital drainage-area
data for 45 selected stream-sampling stations in the Yellowstone River Basin
are included in this data release. The drainage divides were identified
chiefly using 1:100,000-scale (50 m accuracy) hypsography. Drainage areas
based on 1:100,000-scale hypsography data generally agree to within 5 percent
with drainage areas measured at 1:24,000 scale, for areas larger than 50 km2.