Table 1.  Drainage basin size and cultural characteristics of 
National Stream Quality Accounting Network watersheds  

[NASQAN, National Stream Quality Accounting Network.  The drainage
area statistics exclude 29 watersheds with interderminant area.
The cultural characteristics were estimated using digital drainage 
boundaries for 507 NASQAN stations.  Accounting unit boundaries were 
used for 85 NASQAN stations without digitized drainage basin boundaries.  
Cultural characteristics are not available for 26 stations located outside 
of the conterminous United States.  Population data are from 1990 (U.S. 
Bureau of Census, 1991), and land-cover statistics are for 1987 (U.S. 
Soil Conservation Service, 1989)]

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Characteristic         Range              Percentiles of station watersheds
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                Minimum     Maximum     25th            50th            75th
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                             NASQAN basins
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Drainage area
   (mi2)            1      1,140,500    1,238          4,390          14,910
Population
 density(#/mi2)   0.7          2,577     14.3           41.3           108.3
Crop area (%)       0           90.4      4.5           12.4            29.3
Forest area(%)      0           87.7      3.4           17.4            50.6
Urban area(%)       0           43.3      0.7            2.0             4.5
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           334 accounting units in the conterminous United States
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Drainage area
   (mi2)          121         47,740    4,751          7,838          11,613
Population
 density(#/mi2)   1.3          3,971     13.9           47.8           118.7
Crop area (%)     0.1           81.1      5.0           14.5            31.5
Forest area(%)      0           84.5      2.0           15.8            45.4
Urban area(%)     0.1           42.9      0.7            2.3             4.7
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