Concentrations of contaminants found in stormwater

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.