How are county contamination rankings calculated?

Rankings use severity-weighted density: the sum of contamination site severity scores divided by county area in square miles. Higher-severity sources (Superfund, PFAS, mining) contribute more to the density score than lower-severity sources (UST, nitrate). Data from 9 federal databases including EPA FRS, USGS MRDS, and USGS NAWQA.

Does a high contamination ranking mean I cannot grow food?

No. County-level rankings are a screening tool. Contamination risk depends on proximity to specific sites, soil type, water source, and what you grow. Most parcels in high-ranking counties are perfectly safe for gardening. Get a site-specific report to check your actual parcel.

Data Story

County Contamination Rankings for Growers

Which US counties have the most — and fewest — documented contamination sources near gardens?

Data from 9 federal databases (EPA, USGS). 1.8 million sites analyzed.

Rank	County	State	Dominant Source	Total Sites
#1	Kusilvak	AK	Nitrate	40
#2	North Slope	AK	Brownfields	331
#3	Borden	TX	Underground Storage Tanks	6
#4	Dillingham	AK	Mining	82
#5	Grant	NE	Nitrate	6
#6	Kent	TX	Underground Storage Tanks	9
#7	Terrell	TX	Underground Storage Tanks	25
#8	Lake and Peninsula	AK	Mining	144
#9	Hooker	NE	Underground Storage Tanks	7
#10	Jeff Davis	TX	Underground Storage Tanks	21
#11	Yukon-Koyukuk	AK	Mining	926
#12	Motley	TX	Underground Storage Tanks	11
#13	Yakutat	AK	Mining	74
#14	Bethel	AK	Mining	340
#15	Northwest Arctic	AK	Mining	279
#16	Edwards	TX	Underground Storage Tanks	26
#17	Loving	TX	Toxic Release Inventory	8
#18	Thomas	NE	Underground Storage Tanks	7
#19	Cherry	NE	Nitrate	70
#20	Cottle	TX	Underground Storage Tanks	16
#21	Throckmorton	TX	Underground Storage Tanks	15
#22	Crockett	TX	Underground Storage Tanks	50
#23	Las Animas	CO	Underground Storage Tanks	104
#24	Irion	TX	Underground Storage Tanks	20
#25	Briscoe	TX	Underground Storage Tanks	20
#26	Schleicher	TX	Underground Storage Tanks	30
#27	Roberts	TX	Underground Storage Tanks	20
#28	Sterling	TX	Underground Storage Tanks	23
#29	Armstrong	TX	Underground Storage Tanks	22
#30	Mora	NM	Underground Storage Tanks	44
#31	Southeast Fairbanks	AK	Mining	373
#32	Arthur	NE	Nitrate	12
#33	Dawes	NE	Underground Storage Tanks	28
#34	Dickens	TX	Underground Storage Tanks	23
#35	Menard	TX	Underground Storage Tanks	20
#36	Kane	UT	Underground Storage Tanks	84
#37	Concho	TX	Underground Storage Tanks	29
#38	Lincoln	CO	Underground Storage Tanks	73
#39	Rich	UT	Underground Storage Tanks	26
#40	Hayes	NE	Nitrate	14
#41	Blaine	NE	Nitrate	16
#42	Foard	TX	Mining	15
#43	Glasscock	TX	Toxic Release Inventory	22
#44	Brewster	TX	Underground Storage Tanks	126
#45	Garfield	MT	Nitrate	99
#46	Guadalupe	NM	Underground Storage Tanks	98
#47	Frontier	NE	Underground Storage Tanks	23
#48	Wibaux	MT	Nitrate	21
#49	Sutton	TX	Underground Storage Tanks	40
#50	Oldham	TX	Underground Storage Tanks	43