



MEAN TOTAL NITROGEN CONCENTRATIONS 

 vs. LAND USE 



1.0 2.0 3.0 



MILLIGRAMS PER LITER 



4.0 



Figure 1. The relationship between mean total nitrogen concen- 

 trations in streams and land use in the Eastern United States. 



MEAN TOTAL PHOSPHORUS CONCENTRATIONS 

 vs. LAND USE 



AGRI- 

 CULTURE 



0.05 



MILLIGRAMS 



0.10 



PER LITER 



0.15 



Figure 2. The relationship between mean total phosphorus concen- 

 trations in streams and land use in the Eastern United States. 



93 



