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Federal
Map of Arsenic concentrations in groundwater of the United States
Department of the Interior —
The map graphic image at https://www.sciencebase.gov/catalog/file/get/63140561d34e36012efa2b7f?name=arsenic_map.png illustrates arsenic values, in micrograms per... -
Federal
Tillage Practices in the Conterminous United States, 1989-2004--Datasets Aggregated by Watershed; tillage_lu92e
Department of the Interior —
This dataset is an aggregation of county-level tillage practices to the 8-digit hydrologic unit watershed. The original county-level data were collected by the...