Median pollutant removal of bacteria by stormwater treatment practices. Values represent percentage of incoming pollutant load that is removed. Source: Minnesota Stormwater Manual. Manual data was based on information from ASCE/EPA International Database; Winer (2000)
BMP group Bacteriaa>
Bioretentionb 85
Filtrationc 85
Infiltrationd 100
Stormwater ponds 80
Stormwater wetlands 75

aBacteria data include fecal streptococci, fecal coliform, E. coli, and total coliform bData based on fewer than five monitoring studies
cExcludes vertical sand filters and filter strips
dNote that 100% is assumed for all infiltration, but only for that portion of the flow fully treated in the infiltration facility; by-passed runoff does not receive any treatment.