Kazuhiro Sonoda, J. Alan Yeakley, and Christopher E. Walker.  2001.  Near-stream landuse effects on streamwater nutrient distribution in an urbanizing watershed.  Journal of the American Water Resources Association 37: 1517-1532

Abstract

We investigated spatial and temporal relationships among surface and subsurface watershed attributes and stream nutrient concentrations in urbanizing Johnson Creek watershed in northern Oregon.  We sampled stream water at 8 urban and 5 non-urban locations from March 1998 through December 1999.  We sampled 8 wells distributed over the two primary aquifers in the watershed.  Using a Geographic Information System (GIS), percentages of landuse attributes within a radius of 30, 91, and 152 m from each sample site were quantified.  We analyzed relationships between 1) nutrient concentrations and percentage cover of different landuse attributes, and 2) nutrient concentrations and underlying hydrologic units.  We did not find a significant relationship between groundwater chemistry and stream water chemistry.  We found elevated levels of phosphorus (P) concentrations correlated with urban landuse, while higher nitrogen (N) concentrations were correlated with non-urban (primarily agricultural) landuse.  We concluded that elevated levels of N in non-urban areas of Johnson Creek watershed were associated with agricultural practices.  We further concluded that urban development factors such as increases in storm drains, dry wells, and impermeable surfaces may be responsible for higher input of P to the stream in urbanizing areas of the Johnson Creek watershed.