Table 3. Pollutant Concentrations by Land Use: Total Nitrogen (mg/l)

Land Use
Source Residential Commercial Roadway Industrial Notes
Schueler, 1987 mean 2.0 2.17 - - These values are taken from a Washington DC NURP study in 1980-81. At least 27 storm events were sampled at multiple sites within the specified land use.
Gibb et al., 1991 mean 1.5 - 2.72 - These values represent recommended estimates for planning purposes and are based on analysis of mean concentrations from over 13 studies from the US and British Columbia.
Smullen and Cave, 1998 median 2.0 2.0 2.0 2.0 This study probably represents the most comprehensive data set, with 3,047 event samples being included from across the nation. The data includes pooled NURP, USGS, and NPDES sources. The value is a median of EMCs and applies to general urban runoff (i.e., mixed land uses).
US EPA, 1983 median 2.6 1.75 - - These values represent NURP data for residential and commercial land use. NURP data were collected in the early 1980s in over 28 different metropolitan areas across the US.
Barrett and Malina, 1998 - - 3.48 - This data reflects a study of vegetative swales treating highway runoff in Austin, TX. Value represents average of the mean inflow concentrations measured at 2 sites. Data were collected over 34 storm events.
Caraco and Schueler (1999). Arid Climates 4.06 4.06 4.06 4.06 This value represents an average of EMC data collected from 3 arid climate locales (Phoenix, Boise, and Denver). A total of 90 data points are used, with each site having at least 16 data points. The value applies to general urban runoff (i.e., mixed land uses).
Whalen and Cullum, 1988 2.03 2.3 - 2.53 These data are from an assessment of urban runoff quality that looked at NURP and State of Florida data. The NURP data summaries are what is shown. Residential and commercial values are mean values for specified land uses and reflect between 200 and 1,100 sampling events depending on the parameter and land use. Industrial values are from 4 NURP sites and generally represent light industrial land use.
Model default Value1 2.2 2.0 3.0 2.5
1: The model default values represent best professional judgement, and give additional weight to studies conducted at a national level. Data do not incorporate studies on arid climates.