Generalized boundaries of the National Water-Quality Assessment (NAWQA) Study-Unit Investigations in the conterminous United States 1991-2001

This is a GENERALIZED version of the boundaries and codes used
for the U.S. Geological Survey's National Water-Quality
Assessment (NAWQA) Program Study-Unit investigations in the
conterminous United States, excluding the High Plains Regional
Ground-Water Study. The data set represents the areas studied
during the first decade of the NAWQA Program, from 1991-2001
("cycle 1"). The coverage is intended only for drawing
ILLUSTRATIONS, NOT for spatial analysis.

The sources of this coverage were the full resolution NAWQA study
unit coverage, which is available at
https://water.usgs.gov/lookup/getspatial?nawqacyc1 and the
coastline from a 1:2 million county coverage generalized for
display at the scale of 1:34 million.