Pollution Analyst
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National rankings · 2024

Top Superfund Site Rankings: Most Contaminated & Highest Risk

EPA's Superfund program tracks the country's most hazardous contaminated sites — current and former industrial, military, and waste-disposal properties on the National Priorities List. Unlike TRI, SEMS doesn't publish a pounds figure for each site, so we rank the biggest and worst Superfund sites by two data-driven signals instead: contamination breadth (distinct contaminants reported) and downstream risk (groundwater utilities within roughly five miles), rather than by acreage or cleanup cost. Every site on these tables is by definition contaminated; ranking the “least polluted” isn't a meaningful question. For the full program — what a Superfund site is, how cleanup works, and the law behind it — see our guide to understanding the Superfund program. Spans 50 ingested states (1,814 NPL sites total).

1,814
Superfund (NPL) sites tracked in the U.S.Across 50 states, drawn from EPA's SEMS database. New Jersey leads with 153. Historical context & full statistics →

Top 20 Most Contaminated Superfund Sites — Most Contaminants Reported (distinct contaminants)What this meansDistinct contaminants of concern logged for the site under EPA's Superfund Enterprise Management System (SEMS). A larger count signals a more chemically complex contamination footprint — not necessarily higher mass — across groundwater, soil, sediment, and surface-water media.

NPL sites with the most distinct contaminants of concern logged in EPA's SEMS database — chemical complexity rather than mass.

Methodology →

Superfund / NPL sites ranked by most contaminants reported (distinct contaminants), highest first.
#SiteCityCountyStatePrimary contaminantMost Contaminants Reported
1Savannah River Site (Usdoe)· federal facilityAiken—South CarolinaCesium-137Health riskBeta/gamma emitter (half-life ~30 yr); whole-body irradiator; legacy of nuclear weapons fallout and reactor accidents. (EPA)395
2American Cyanamid CoFinderneSomersetNew JerseyBenzeneHealth riskIARC Group 1 carcinogen. Long-term inhalation causes leukemia and bone-marrow disorders. (IARC, EPA)331
3Mcclellan Air Force Base (Ground Water Contamination)· federal facilityMcClellan ParkSacramentoCaliforniaArsenicHealth riskIARC Group 1 carcinogen via inhalation and ingestion. EPA MCL 10 µg/L; chronic exposure causes skin, lung, bladder cancer and cardiovascular disease. (IARC, EPA, ATSDR)327
4Rocky Mountain Arsenal (Usarmy)· federal facilityAdams CountyAdamsColoradoAldrinHealth riskMetabolizes to dieldrin in the body. EPA classifies as 'probable human carcinogen'; banned in the US in 1987. (EPA, ATSDR)298
5Pease Air Force Base· federal facilityPortsmouthRockinghamNew HampshireManganeseHealth riskExcess inhalation can cause manganism, a Parkinson-like neurological disorder. (ATSDR)286
6Lowry LandfillUnincorporated Arapahoe CountyArapahoeColorado1,1,1-TrichloroethaneHealth riskMethyl chloroform. CNS depressant; ozone-depleting substance phased out under Montreal Protocol. EPA MCL 200 µg/L. (EPA, ATSDR)267
7Feed Materials Production Center (Usdoe)· federal facilityFernald—OhioTechnetium-99264
8Portland HarborPortlandMultnomahOregon1,1-DichloroetheneHealth riskVinylidene chloride; IARC Group 3 (inadequate evidence in humans) but liver toxic in animal studies; common TCE/PCE biodegradation product. (IARC, EPA)259
9Himco DumpElkhartElkhartIndiana1,1-DichloroethaneHealth riskSuspected carcinogen (EPA C/likely); CNS depressant. Common at solvent-contaminated sites as a degradation intermediate. (EPA, ATSDR)247
10Onondaga LakeSyracuseOnondagaNew YorkArsenicHealth riskIARC Group 1 carcinogen via inhalation and ingestion. EPA MCL 10 µg/L; chronic exposure causes skin, lung, bladder cancer and cardiovascular disease. (IARC, EPA, ATSDR)238
11Shpack LandfillNorton/AttleboroBristolMassachusetts1,1-DichloroetheneHealth riskVinylidene chloride; IARC Group 3 (inadequate evidence in humans) but liver toxic in animal studies; common TCE/PCE biodegradation product. (IARC, EPA)230
12Woodstock Municipal LandfillWoodstockMchenryIllinoisChloroethene (Vinyl Chloride)Health riskIARC Group 1 carcinogen — angiosarcoma of the liver. Final TCE/PCE biodegradation product; commonly found in groundwater plumes. EPA MCL 2 µg/L. (IARC, EPA)225
13Hunters Point Naval Shipyard· federal facilitySan FranciscoSan FranciscoCaliforniaArsenicHealth riskIARC Group 1 carcinogen via inhalation and ingestion. EPA MCL 10 µg/L; chronic exposure causes skin, lung, bladder cancer and cardiovascular disease. (IARC, EPA, ATSDR)223
14Ormet Corp.HannibalMonroeOhio1,1,1-TrichloroethaneHealth riskMethyl chloroform. CNS depressant; ozone-depleting substance phased out under Montreal Protocol. EPA MCL 200 µg/L. (EPA, ATSDR)212
15Gems LandfillGloucester TownshipCamdenNew Jersey1,1,1-TrichloroethaneHealth riskMethyl chloroform. CNS depressant; ozone-depleting substance phased out under Montreal Protocol. EPA MCL 200 µg/L. (EPA, ATSDR)211
16Fields BrookAshtabulaAshtabulaOhioHexachlorobenzene208
17Loring Air Force Base· federal facilityLimestoneAroostookMaineBenzo[A]AnthraceneHealth riskPAH; IARC Group 2B possible carcinogen; common combustion byproduct and creosote constituent. (IARC)202
18Otis Air National Guard Base/Camp Edwards· federal facilityFalmouthBarnstableMassachusettsTrichloroetheneHealth riskTCE. IARC Group 1 carcinogen — kidney cancer; suspected liver cancer and non-Hodgkin lymphoma. EPA MCL 5 µg/L; common DNAPL groundwater plume contaminant. (IARC, EPA, ATSDR)191
19Oak Ridge Reservation (Usdoe)· federal facilityOak Ridge—TennesseeMercuryHealth riskNeurotoxin. Methylmercury bioaccumulates up the food chain and damages the developing nervous system. (EPA, ATSDR)191
20Motco, Inc.La MarqueGalvestonTexas1,1,2-Trichloroethane190

Top 10 Most Contaminated Superfund Sites — Most Nearby Groundwater Utilities (PWSes within 5 mi)What this meansPublic water systems drawing groundwater within roughly 5 miles of the NPL site. Distance is computed from site coordinates to served-city centroids — coarse on purpose. A non-zero count means downstream drinking-water exposure is at least geographically plausible.

NPL sites with the most groundwater-drawing public water systems within roughly five miles — geographic proximity, not confirmed contamination.

Methodology →

Superfund / NPL sites ranked by most nearby groundwater utilities (PWSes within 5 mi), highest first.
#SiteCityCountyStatePeople servedMost Nearby Groundwater Utilities
1North Cavalcade StreetHoustonHarrisTexas1,364,236390 utilities
2South Cavalcade StreetHoustonHarrisTexas1,364,236390 utilities
3Bremerton GasworksBremertonKitsapWashington88,804271 utilities
4Puget Sound Naval Shipyard Complex· federal facilityBremertonKitsapWashington88,804271 utilities
5Commencement Bay, South Tacoma ChannelTacomaPierceWashington121,914126 utilities
6Commencement Bay, Near Shore/Tide FlatsTacomaPierceWashington113,987125 utilities
7Yakima Plating Co.YakimaYakimaWashington69,59789 utilities
8Pesticide Lab (Yakima)YakimaYakimaWashington63,16488 utilities
9Jibboom JunkyardSacramentoSacramentoCalifornia68,99659 utilities
10Mccormick & Baxter Creosoting Co.StocktonSan JoaquinCalifornia18,03658 utilities

Understanding Superfund Site Contamination Metrics

Distinct contaminants reported. This is a count of chemical complexity, not mass. A high count means EPA's decision documents name a wide array of different pollutants across multiple media — groundwater, soil, sediment, and surface water — signalling a multifaceted cleanup challenge. It does not mean more tons of waste are present. For why breadth is a useful rankable signal and how it differs from other criteria, see types of contamination found at Superfund sites.

Nearby groundwater utilities (PWSes within ~5 mi). This counts SDWIS-registered public water systems that draw from groundwater within roughly five miles of a site — a measure of potential drinking-water exposure. It reflects geographic plausibility, not confirmed contamination: SDWIS does not expose individual wellhead locations, and proximity alone cannot establish that contamination has reached a utility's intake.

Why these metrics. SEMS publishes neither a single severity score nor a pounds-of-waste figure per site, so the conventional “largest” or “worst” framings — acreage, waste volume, cleanup cost — aren't uniformly available across all sites. Contamination breadth and groundwater proximity are both consistently recorded in the federal data, which lets us rank every NPL site on the same basis and surface the signals that most inform EPA priorities and community risk. See the methodology for the full sourcing and caveats.

Superfund Sites by State: Which States Have the Most?

NPL site counts per state across the 1,814 sites tracked. New Jersey carries the most (153); states with deep industrial and military legacies cluster at the top. Below are the ten states with the most Superfund sites.

  1. 1New Jersey153
  2. 2Pennsylvania127
  3. 3New York122
  4. 4California117
  5. 5Michigan90
  6. 6Florida81
  7. 7Texas70
  8. 8Washington69
  9. 9Illinois56
  10. 10Indiana54

Browse all NPL sites in any state from its state pollution page. Source: EPA SEMS via Pollution Analyst pipeline.

Frequently Asked Questions About Superfund Site Rankings

How many Superfund sites are there in the U.S.?
Pollution Analyst tracks 1,814 National Priorities List (NPL) sites across 50 states, drawn from EPA's SEMS database. The count combines NPL Final sites under active cleanup oversight and NPL Deleted sites where EPA has certified cleanup complete, and it fluctuates as sites are added or deleted. See our Superfund guide for the full program history and statistics.
Which U.S. states have the most Superfund sites?
By our data, New Jersey (153), Pennsylvania (127), New York (122), California (117), Michigan (90) carry the most NPL sites — reflecting their industrial histories and population densities. The full state-by-state distribution is in the "Superfund sites by state" section above.
What are the largest or worst Superfund sites in the USA?
"Largest" and "worst" can mean different things — physical acreage, volume of waste, cost of cleanup, or breadth of contamination. EPA's SEMS database does not publish a single severity score or a pounds-of-waste figure per site, so we rank by two data-driven signals instead: distinct contaminants reported (chemical complexity) and nearby groundwater utilities (downstream drinking-water risk). The sites at the top of these tables — heavily federal facilities such as Cold War military and Department of Energy nuclear sites — are among the most complex in the country.
What does 'distinct contaminants reported' mean for a Superfund site?
It quantifies chemical complexity, not mass. The figure counts the distinct contaminants of concern cited in EPA's decision documents for a site across all media — groundwater, soil, sediment, and surface water. A higher number indicates a wider array of different pollutants and a more multifaceted cleanup challenge; it does not mean more tons of waste are present.
How does Superfund site proximity affect nearby groundwater?
The "nearby groundwater utilities" metric counts SDWIS-registered public water systems drawing from groundwater within roughly five miles of a site. It flags a potential exposure pathway that warrants investigation — if contamination migrates to an aquifer a utility draws from, drinking water can be affected. Proximity alone reflects geographic plausibility, not confirmed contamination.