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Event mean concentrations for total phosphorus

Event mean concentrations for total phosphorus
Event mean concentrations (EMCs) for total phosphorus.
Land cover/land use Range (mg/L) Recommended value (mg/L) Notes
Commercial 0.20 - 0.34 0.200 If applicable to models being used, adjust curve numbers/runoff coefficients when calculating loads
Industrial 0.23 - 0.55 0.235
  • If applicable to models being used, adjust curve numbers/runoff coefficients when calculating loads
  • Adjust upward if specific phosphorus sources exist
Residential 0.26 - 0.38 0.325 Concentrations vary widely depending on local conditions
High-density/Multi-family residential 0.28 - 0.40 Calculate1
  • Insufficient information to recommend a specific EMC
  • Concentrations vary widely depending on local conditions
Medium density residential 0.18 - 0.40 Calculate1
  • Insufficient information to recommend a specific EMC
  • Concentrations vary widely depending on local conditions
Low density residential 0.24 - 0.40 Calculate1
  • Insufficient information to recommend a specific EMC
  • Concentrations vary widely depending on local conditions
Freeways/transportation 0.25 - 0.45 0.280
  • Concentrations vary widely depending on inputs
  • Adjust upward for areas receiving large inputs of road salt or sediment or having very heavy traffic loads
  • Adjust downward for low traffic areas or areas with reduced inputs (e.g. little road salt application, limited truck traffic)
Mixed 0.16 - 0.84 0.290
  • Residential land use was the primary land use in most studies that cited values for mixed land use
  • If the study area can be delineated into specific land uses and impervious area for each land use is know, we recommend calculating the EMC
Parks and recreation   Use value for open space or calculate
  • EMC will be a function of vegetative cover
  • Adjust upward if street tree canopy cover is high or pervious areas are primarily grass on compacted soils
Open space 0.12 - 0.31 0.190  
Conventional roof 0.01 - 0.20 0.030  
Institutional 0.14 - 0.422 See note
  • Use low values in range (0.200 mg/L or less) for facilities such as campuses, where there is considerable pervious area
  • Use high values in range (0.30 mg/L or greater) for areas with considerable impervious surface, such as sports facilities or facilities with large parking areas
Forest/shrub/grassland 0.03 - 0.45 0.090 Concentrations are likely to vary with season in areas with fall leaf drop
Open water and wetlands   see Notes (next column)
  • If data exist, use the phosphorus concentration for the water body of interest
  • If data for a specific lake do not exist, use data from similar lakes in the area
  • EMCs for wetlands will typically be higher than for lakes in an area. Consider using a value equal to 2 times the value for lakes in an area.
Cropland (row crops) 0.126-1.348 Inconclusive2 Median from our review = 0.533
Pasture 0.35-0.45 Inconclusive2  
1The link takes you to information on calculating event mean concentrations for areas with multiple land uses.
2Our literature review was not extensive enough to warrant a specific recommend EMC for this land use.
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