National rankings · 2024
Most Contaminated Superfund Sites
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; the rankable signal is contamination breadth (distinct contaminants reported) and downstream risk (groundwater utilities within roughly five miles). Every site on these tables is by definition contaminated; ranking the “least polluted” isn't a meaningful question. Spans 50 ingested states (1,814 NPL sites total).
Top 20 NPL 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.
| # | Site | City | County | State | Primary contaminant | Most Contaminants Reported |
|---|---|---|---|---|---|---|
| 1 | Savannah River Site (Usdoe)· federal facility | Aiken | — | South Carolina | Cesium-137Health riskBeta/gamma emitter (half-life ~30 yr); whole-body irradiator; legacy of nuclear weapons fallout and reactor accidents. (EPA) | 395 |
| 2 | American Cyanamid Co | Finderne | Somerset | New Jersey | BenzeneHealth riskIARC Group 1 carcinogen. Long-term inhalation causes leukemia and bone-marrow disorders. (IARC, EPA) | 331 |
| 3 | Mcclellan Air Force Base (Ground Water Contamination)· federal facility | McClellan Park | Sacramento | California | ArsenicHealth 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 |
| 4 | Rocky Mountain Arsenal (Usarmy)· federal facility | Adams County | Adams | Colorado | AldrinHealth riskMetabolizes to dieldrin in the body. EPA classifies as 'probable human carcinogen'; banned in the US in 1987. (EPA, ATSDR) | 298 |
| 5 | Pease Air Force Base· federal facility | Portsmouth | Rockingham | New Hampshire | ManganeseHealth riskExcess inhalation can cause manganism, a Parkinson-like neurological disorder. (ATSDR) | 286 |
| 6 | Lowry Landfill | Unincorporated Arapahoe County | Arapahoe | Colorado | 1,1,1-TrichloroethaneHealth riskMethyl chloroform. CNS depressant; ozone-depleting substance phased out under Montreal Protocol. EPA MCL 200 µg/L. (EPA, ATSDR) | 267 |
| 7 | Feed Materials Production Center (Usdoe)· federal facility | Fernald | — | Ohio | Technetium-99 | 264 |
| 8 | Portland Harbor | Portland | Multnomah | Oregon | 1,1-DichloroetheneHealth riskVinylidene chloride; IARC Group 3 (inadequate evidence in humans) but liver toxic in animal studies; common TCE/PCE biodegradation product. (IARC, EPA) | 259 |
| 9 | Himco Dump | Elkhart | Elkhart | Indiana | 1,1-DichloroethaneHealth riskSuspected carcinogen (EPA C/likely); CNS depressant. Common at solvent-contaminated sites as a degradation intermediate. (EPA, ATSDR) | 247 |
| 10 | Onondaga Lake | Syracuse | Onondaga | New York | ArsenicHealth 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 |
| 11 | Shpack Landfill | Norton/Attleboro | Bristol | Massachusetts | 1,1-DichloroetheneHealth riskVinylidene chloride; IARC Group 3 (inadequate evidence in humans) but liver toxic in animal studies; common TCE/PCE biodegradation product. (IARC, EPA) | 230 |
| 12 | Woodstock Municipal Landfill | Woodstock | Mchenry | Illinois | Chloroethene (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 |
| 13 | Hunters Point Naval Shipyard· federal facility | San Francisco | San Francisco | California | ArsenicHealth 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 |
| 14 | Ormet Corp. | Hannibal | Monroe | Ohio | 1,1,1-TrichloroethaneHealth riskMethyl chloroform. CNS depressant; ozone-depleting substance phased out under Montreal Protocol. EPA MCL 200 µg/L. (EPA, ATSDR) | 212 |
| 15 | Gems Landfill | Gloucester Township | Camden | New Jersey | 1,1,1-TrichloroethaneHealth riskMethyl chloroform. CNS depressant; ozone-depleting substance phased out under Montreal Protocol. EPA MCL 200 µg/L. (EPA, ATSDR) | 211 |
| 16 | Fields Brook | Ashtabula | Ashtabula | Ohio | Hexachlorobenzene | 208 |
| 17 | Loring Air Force Base· federal facility | Limestone | Aroostook | Maine | Benzo[A]AnthraceneHealth riskPAH; IARC Group 2B possible carcinogen; common combustion byproduct and creosote constituent. (IARC) | 202 |
| 18 | Otis Air National Guard Base/Camp Edwards· federal facility | Falmouth | Barnstable | Massachusetts | TrichloroetheneHealth 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 |
| 19 | Oak Ridge Reservation (Usdoe)· federal facility | Oak Ridge | — | Tennessee | MercuryHealth riskNeurotoxin. Methylmercury bioaccumulates up the food chain and damages the developing nervous system. (EPA, ATSDR) | 191 |
| 20 | Motco, Inc. | La Marque | Galveston | Texas | 1,1,2-Trichloroethane | 190 |
Top 10 NPL 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.
| # | Site | City | County | State | People served | Most Nearby Groundwater Utilities |
|---|---|---|---|---|---|---|
| 1 | North Cavalcade Street | Houston | Harris | Texas | 1,364,236 | 390 utilities |
| 2 | South Cavalcade Street | Houston | Harris | Texas | 1,364,236 | 390 utilities |
| 3 | Bremerton Gasworks | Bremerton | Kitsap | Washington | 88,804 | 271 utilities |
| 4 | Puget Sound Naval Shipyard Complex· federal facility | Bremerton | Kitsap | Washington | 88,804 | 271 utilities |
| 5 | Commencement Bay, South Tacoma Channel | Tacoma | Pierce | Washington | 121,914 | 126 utilities |
| 6 | Commencement Bay, Near Shore/Tide Flats | Tacoma | Pierce | Washington | 113,987 | 125 utilities |
| 7 | Yakima Plating Co. | Yakima | Yakima | Washington | 69,597 | 89 utilities |
| 8 | Pesticide Lab (Yakima) | Yakima | Yakima | Washington | 63,164 | 88 utilities |
| 9 | Jibboom Junkyard | Sacramento | Sacramento | California | 68,996 | 59 utilities |
| 10 | Mccormick & Baxter Creosoting Co. | Stockton | San Joaquin | California | 18,036 | 58 utilities |