Buffer area: area downslope of feedlot between feedlot and discharge point, includes grassed
Discharge point: The discharge point (Figure 1.1.6.) Is the location closest to the feedlot where runoff
changes from sheet flow to channelized flow. When runoff volume becomes channelized, no further
pollutant attenuation occurs from vegetative filtration. The discharge point may be physically defined as
a tile inlet, gully or rill. If a grass waterway is used for feedlot runoff, treatment or discharge, it should
be included as part of the buffer. The discharge point is the end of the effective treatment point or end
of the grass waterway (Young et al., 1982).
Channelized flow area: ditch, gully, or rill
Determine the CN for animal lot Area 1, from Table 1.1.4 Curve Numbers for Areas 2 and 3
can be determined from Table 1.1.1.
Define feedlot animal types and determine pollutant ratios from Table 1.1.4.
The pollutant concentration (C1) for Area 1 feedlot animal waste may be determined by the
Determine animal unit density (AUD) :
AUD = EAU/A (if AUD > 100, use 100)
EAU = equivalent animal units
= Number of animals X pollutant ratio
A = area of feedlot area (acres)