National Land Cover Database 2001 (NLCD01) Imperviousness Layer Tile 1, Northwest United States: IMPV01_1
This 30-meter resolution data set represents the imperviousness layer for the conterminous United States 
for the 2001 time period. The data have been arranged into four tiles to facilitate timely display and 
manipulation within a Geographic Information System, browse graphic: nlcd01-partition. The National 
Land …