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1:250,000-scale Hydrologic Units of the United States

January 1, 1994

The Geographic Information Retrieval and Analysis System (GIRAS) was developed in the mid 70s to put into digital form a numberof data layers which were of interest to the USGS. One of these data layers was the Hydrologic Units. The map is based on the Hydrologic Unit Maps published by the U.S. Geological Survey Office of Water Data Coordination, together with the list descriptions and name of region, subregion, accounting units, and cataloging unit. The hydrologic units are encoded with an eight-digit number that indicates the hydrologic region (first two digits), hydrologic subregion (second two digits), accounting unit (third two digits), and cataloging unit (fourth two digits). The data produced by GIRAS was originally collected at a scale of 1:250K. Some areas, notably major cities in the west, were recompiled at a scale of 1:100K. In order to join the data together and use the data in a geographic information system (GIS) the data were processed in the ARC/INFO GUS software package. Within the GIS, the data were edgematched and the neatline boundaries between maps were removed to create a single data set for the conterminous
United States. NOTE: A version of this data theme that is more throughly checked (though based on smaller-scale maps) is available here: http://water.usgs.gov/lookup/getspatial?huc2m

Publication Year 1994
Title 1:250,000-scale Hydrologic Units of the United States
DOI 10.3133/ofr19940236
Authors Peter Steeves, Douglas Nebert
Publication Type Report
Publication Subtype USGS Numbered Series
Series Title Open-File Report
Series Number 1994-0236
Index ID ofr19940236
Record Source USGS Publications Warehouse