Table 1.  Parameter estimates, probability levels and 
regression results for national SPARROW model (modified 
from Smith and others, 1997).

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Model parameters                Bootstrap     Bootstrap
                               Coefficient        p
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Nitrogen Sources (beta)
  Point sources                    0.4331       <0.005
  Fertilizer application           1.439        <0.005
  Livestock waste production       1.060         0.005
  Atmospheric deposition           6.538        <0.005
  Nonagricultural land            16.71         <0.005

Land to water deliver (alpha)
  Temperature                      0.0198       <0.005
  Slope
  Soil permeability                0.0450       <0.005
  Stream density                   0.0244        0.025
  Wetland
  Irrigated land
  Precipitation
  Irrigated water use

Instream loss (gamma)
  gamma1 (Q<28.3 m3/s)             0.3843       <0.005
  gamma2 (28.3 m3/s<Q<283 m3/s)    0.1225       <0.005
  gamma3 (Q>283 m3/s)              0.0407        0.015

R-squared                          0.8742
Mean square error                  0.4544
Number of observations           414
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