Concentrations of contaminants found in stormwater. Note that median concentrations are lower than event mean concentrations shown in this manual. This is because concentration data is typically positively skewed. Source: International Stormwater Database.7. Note that the table does not include information for chloride, a common pollutant in stormwater. Chloride concentrations vary seasonally and would be misrepresented in a single table. For more information on chloride concentrations in stormwater, see here.
Link to this table.

Land use TSS 1 NO2 + NO3 1 TN 1 TP 1 Cu 2 Zn 2 Ni 2 Cd 2 Cr 2 CN 2,5 Oil and grease 2 VOCs 2,5 Pesticides 2,4,5 FC 3,5 EC 3,5 FS 3,5
Commercial
Number of sites 56 50 13 56 60 62 40 51 38 2 44 4 1 4 -- 3
Number of observations 857 786 77 948 785 867 291 543 294 6 394 160 6 19 -- 7
% of samples above detection 98.7 98.9 97.4 94.5 85 99.2 51.5 38.1 52.0 0 65.5 65.5 0 73.7 -- 100
Minimum <0.5 <0.1 <1.5 <0.01 <0.2 <0.3 <1 <0.03 <0.7 n/a <0.5 <0.05 n/a <200 -- 310
Maximum 2385 8.2 18.1 4.27 569.1 3050.5 110 80 100 n/a 359 n/a 28000 -- 24000
Median 52 0.6 1.75 0.2 17 110 8 BDL6 4 BDL 5 0.7 n/a 450 -- 3100
Industrial
Number of sites 58 51 13 57 65 67 43 60 42 2 48 3 -- 6 -- 4
Number of observations 619 536 85 638 569 627 300 525 312 9 370 144 -- 32 -- 12
% samples above detection 99.5 97.0 95.3 95.1 85.1 98.9 58.0 48.6 72.4 0 59.7 10.4 -- 90.6 -- 91.7
Minimum <1 <0.02 <1.5 <0.02 <0.2 <0.5 <2 <0.03 <0.7 n/a <0.5 <0.05 -- <1 -- <1
Maximum 2490 8.4 15.2 7.9 1360 8100 120 334 150 n/a 408 -- 3600000 -- 48000
Median 75 0.68 1.7 0.23 19 155 10 BDL 10 BDL 5 BDL -- 3950 -- 24000
Residential
Number of sites 146 127 20 148 147 151 77 114 72 -- 95 7 1 10 3 4
Number of observations 2257 1772 131 2380 1743 2013 418 1123 408 -- 694 210 6 94 19 23
% of sample above detection 99.9 99.0 98.5 98.2 86.5 97.0 42.2 40.4 48.8 -- 56.8 20.1 0 85.9 100 95.7
Minimum <0.5 <0.03 <1.5 <0.01 <0.2 <0.5 <0.5 <0.03 <0.7 -- <0.5 <0.05 n/a <1 10 <1
Maximum 4168 66.4 18.3 19.90 590 14700 100 70 70 -- 419 3.42 n/a 5230000 35000 200000
Median 58 0.60 2.24 0.26 11 69.9 5 BDL 3 -- 4 BDL BDL 9400 1000 23500
Open space
Number of sites 15 13 4 15 12 12 9 8 7 3 9 1 -- 2 1 --
Number of observations 105 109 13 111 44 49 38 41 36 13 26 5 -- 6 5 --
% of samples above detection 97.1 92.7 92.3 93.7 64.4 65.3 23.1 39.0 36.1 15.4 34.6 60.0 -- 100 100 --
Minimum <1 <0.1 <0.5 <0.01 <0.8 <5 <2 <0.04 <0.7 <0.01 <1 <0.2 -- 1900 100 --
Maximum 4168 3.4 3.3 0.76 210 390 100 8 120 0.08 11 0.84 -- 63000 4700 --
Median 58 0.5 1.1 0.129 6 25 BDL BDL BDL BDL BDL 0.77 -- 2150 1100 --
Rooftop Water quality from rooftops varies with the type of roof. For more information see the section on Water quality considerations for stormwater and rainwater harvest and use/reuse

TSS=total suspended solids, NO2=nitrite, NO3=nitrate, TN=total nitrogen, Cl=chloride, Cu=copper, Zn=zinc, Ni=nickel, Cd=cadmium, Cr=chromium, CN=cyanide, VOC=volatile organic compound, FC=fecal coliform, EC=E. coli, FS=fecal streptococci
1 Concentrations are in milligrams per liter
2 Concentrations are in micrograms per liter
3 Concentrations are in Number per 100 milliliters
4Data is for trans-1,3-Dichloropropene and bromomethane
5 Data was selected from states with a similar climate to MN. The appropriate states were determined using Figure 1.3 from the Stormwater BMP Design Supplement for Cold Climates document.
6BDL = below detection level
7The following censoring techniques were used for this data:

  • If detection rates were 90% or greater, a value of "0" was substituted for non-detects.
  • If detection rates were greater than 50% but 90% or less, a value of 1/2 the detection limit was substituted for non-detects.
  • If detection rates were 50% or less, the median was assumed to be below the method detection level.

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