Drainage areas for selected stream-sampling stations, Missouri River Basin

As part of the U.S. Geological Survey's (USGS) National Water-Quality Assessment Program (NAWQA),
an investigation of the Missouri River Basin is being conducted to document trends in surface-water quality,
specifically for trends in nutrients and suspended sediment. Surface-water samples were collected from
streams 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 boundary data for one stream-sampling
station in the Missouri River Basin (MRB4) study area is included in this data release. The drainage
divides were identified chiefly using 1:24,000-scale hypsography.