Attributes for NHDPlus Version 2.1 Catchments and Modified Routing of Upstream Watersheds for the Conterminous United States: Major Sites of the National Pollutant Discharge Elimination System (NPDES)

This tabular data set represents the number and density of major National Pollutant Discharge Elimination System (NPDES) sites, as defined by Environmental Protection...本表格数据集统计了由国家污染物排放消除系统（National Pollutant Discharge Elimination System，简称NPDES）所定义的主要排放点位的数量与密度，其界定标准由环境保护（Environmental Protection）相关主体制定。