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

These data were released prior to the October 1, 2016 effective date for the USGS’s policy dictating the review, approval, and release of scientific data as referenced in USGS Survey Manual Chapter 502.8 Fundamental Science Practices: Review and Approval of Scientific Data for Release. 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 [...]

本数据集发布于美国地质调查局（U.S. Geological Survey，简称USGS）科学数据审核、批准与发布政策的生效日期（2016年10月1日）之前；该政策详见《USGS勘测手册第502.8章：基础科学实践：科学数据发布的审核与批准》。
作为美国地质调查局国家水质评估计划的组成部分，研究团队正对黄石河流域研究单元开展调查，以记录区域地表与地下水水质的现状及变化趋势。为高效量化该研究单元的各类环境与地理特征，需使用研究单元边界数字地图，并可将其与其他数字专题地图（如[...]）一并进行处理。