As stormwater travels across the land surface into infiltration BMPs, it can pick up various pollutants and deliver them to the subsurface. The fate and transport of these pollutants into soil, the vadose zone and ultimately groundwater depends on the type and amount of pollutant present, the volume of infiltration, the type of infiltration BMP, and subsurface conditions.

Typical stormwater pollutants

Common stormwater pollutants and their most important sources are described in the first table below. The second table provides typical pollutant concentrations in stormwater runoff. The concentrations are based on data from the International Stormwater Database.

Common pollutants of concern and sources in stormwater runoff. Adapted from USGS, 2014.
Link to this table.

Contaminant Contaminant source1
Nitrogen Naturally occurring from vegetation decomposition. Anthropogenic sources include fertilizers, farm-animal waste, faulty septic systems
Chloride Salts applied to roads and parking lots during the winter. Natural sources include mineral dissolution
Copper Industrial and domestic waste, mining, mineral leaching, automobile parts and fluids
Zinc Industrial waste; automobile parts and fluids
Manganese Found naturally in sediment and rocks. Anthropogenic sources include mining waste, industrial waste, automobile parts and fluids
Nickel Naturally occurring. Anthropogenic sources include stainless steel and alloy products, mining, refining, automobile parts and fluids
Cadmium Small amounts are naturally occurring. Anthropogenic sources include industrial discharge, mining waste, automobile parts and fluids
Chromium Old mining operations; fossil-fuel combustion; mineral leaching; automobile parts and fluids
Pesticides Residential use of lawn care products; commercial landscaping; animal wastes; municipal right-of-ways; agriculture; feedlots
Cyanide Road salt; fertilizer production
PAHs2 Auto emissions; elicit discharges; asphalt pavement (driveways, roadways and parking lots) with coal tar sealants3
VOCs2 Crude oil; insecticides; varnishes; paints; gasoline products; degreasers; municipal maintenance activities
Oil and grease Gasoline products; plastics; dyes; rubbers; polishes; solvents; crude oil; insecticides; inks; varnishes; paints; disinfectants; paint removers; degreasers; automobile fluids
Microbes (including fecal coliform, E. coli, and pathogens) Domestic sewage; animal waste; plant or soil material

1The list of sources is for stormwater runoff only
2PAHs=polyaromatic hydrocarbons; VOCs=volatile organic compounds
3MPCA, 2014 Source: USGS, 2014, with permission


Concentrations of contaminants found in stormwater