BMP pollutant removal for total nitrogen BMP pollutant removal for total nitrogen

Median pollutant removal of total nitrogen 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	Total nitrogen
Bioretentiona	45
Filtrationb	35
Infiltrationc	100
Stormwater ponds	30
Stormwater wetlands	30

^aData based on fewer than five monitoring studies
^bExcludes vertical sand filters and filter strips
^cNote 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.