Oroville, CA
Koppers Co., Inc. (Oroville Plant) is listed in the EPA Superfund Enterprise Management System with an NPL status of NPL Site and a Hazard Ranking System (HRS) score of 33.73. The site is located in Oroville, CA. Superfund National Priorities List inclusion is the EPA's formal designation that a contaminated site qualifies for long-term federal cleanup authority under the Comprehensive Environmental Response, Compensation, and Liability Act.
EPA Superfund records catalog 66 contaminants associated with this site, documented through the remedial investigation process. Physical construction of the cleanup remedy has been completed, EPA designates this milestone as "Construction Complete."
NPL listing does not, by itself, establish a health risk to nearby residents, it triggers federal authority to investigate, score, and remediate. HRS scores of 28.50 or above qualify a site for the NPL; the ranking weighs contaminant toxicity, release pathways, waste quantity, and affected population. For current site conditions and community health guidance, contact the California environmental or health agency and the EPA Regional Superfund office listed on the official site profile.
What is the cleanup status of this Superfund site?
Contaminants
| Contaminant | Media |
|---|---|
| 1,2-DIHYDROACENAPHTHYLENE | Groundwater |
| 1,2-DIHYDROACENAPHTHYLENE | Soil |
| 2-PROPAN-2-YLOXYPROPANE | Groundwater |
| 2-PROPAN-2-YLOXYPROPANE | Soil |
| 9H-FLUORENE | Groundwater |
| 9H-FLUORENE | Soil |
| ACENAPHTHYLENE | Groundwater |
| ACENAPHTHYLENE | Soil |
| ANTHRACENE | Groundwater |
| ANTHRACENE | Soil |
| ARSENIC | Groundwater |
| ARSENIC | Soil |
| BARIUM | Groundwater |
| BARIUM | Soil |
| BASE NEUTRAL ACIDS | Groundwater |
| BASE NEUTRAL ACIDS | Soil |
| BENZENE | Groundwater |
| BENZENE | Soil |
| BENZO(B)FLUORANTHENE | Groundwater |
| BENZO(B)FLUORANTHENE | Soil |
| BENZO(K)FLUORANTHENE | Groundwater |
| BENZO(K)FLUORANTHENE | Soil |
| BENZO[A]ANTHRACENE | Groundwater |
| BENZO[A]ANTHRACENE | Soil |
| BENZO[A]PYRENE | Groundwater |
| BENZO[A]PYRENE | Soil |
| BORON OXIDE | Groundwater |
| BORON OXIDE | Soil |
| CARCINOGENIC POLYCYCLIC AROMATIC HYDROCARBONS (cPAH) | Groundwater |
| CARCINOGENIC POLYCYCLIC AROMATIC HYDROCARBONS (cPAH) | Soil |
| CHROMIUM | Groundwater |
| CHROMIUM | Soil |
| CHRYSENE | Groundwater |
| CHRYSENE | Soil |
| COPPER | Groundwater |
| COPPER | Soil |
| DIBENZOFURAN | Groundwater |
| DIBENZOFURAN | Soil |
| DICHLOROMETHANE (METHYLENE CHLORIDE) | Groundwater |
| DICHLOROMETHANE (METHYLENE CHLORIDE) | Soil |
| DIOXINS (CHLORINATED DIBENZODIOXINS) | Groundwater |
| DIOXINS (CHLORINATED DIBENZODIOXINS) | Soil |
| DIOXINS AND DIBENZOFURANS | Groundwater |
| DIOXINS AND DIBENZOFURANS | Soil |
| ETHYLBENZENE | Groundwater |
| ETHYLBENZENE | Soil |
| FLUORANTHENE | Groundwater |
| FLUORANTHENE | Soil |
| INDENO(1,2,3-CD)PYRENE | Groundwater |
| INDENO(1,2,3-CD)PYRENE | Soil |
| NAPHTHALENE | Groundwater |
| NAPHTHALENE | Soil |
| NICKEL | Groundwater |
| NICKEL | Soil |
| PENTACHLOROPHENOL | Groundwater |
| PENTACHLOROPHENOL | Soil |
| PHENANTHRENE | Groundwater |
| PHENANTHRENE | Soil |
| POLYCYCLIC AROMATIC HYDROCARBONS (PAHS) | Groundwater |
| POLYCYCLIC AROMATIC HYDROCARBONS (PAHS) | Soil |
| PYRENE | Groundwater |
| PYRENE | Soil |
| TOLUENE | Groundwater |
| TOLUENE | Soil |
| XYLENE (MIXED ISOMERS) | Groundwater |
| XYLENE (MIXED ISOMERS) | Soil |
Location
Other Superfund Sites in California
| Site Name | Status | HRS Score |
|---|---|---|
| Advanced Micro Devices, Inc. | NPL Site | 37.93 |
| Advanced Micro Devices, Inc. (Building 915) | NPL Site | 31.94 |
| Aerojet General Corp. | NPL Site | 54.63 |
| Afterthought Mine | NPL Site | 50.00 |
| Alameda Naval Air Station | NPL Site | 50.00 |
| Alark Hard Chrome | NPL Site | 50.50 |
| AMCO Chemical | NPL Site | 50.00 |
| Applied Materials | NPL Site | 31.94 |
| Argonaut Mine | NPL Site | 58.31 |
| Atlas Asbestos Mine | NPL Site | 45.55 |
Frequently Asked Questions
What is the Koppers Co., Inc. (Oroville Plant) Superfund site? ▼
Is Koppers Co., Inc. (Oroville Plant) dangerous to live near? ▼
What is the HRS score for Koppers Co., Inc. (Oroville Plant)? ▼
What contaminants are at the Koppers Co., Inc. (Oroville Plant) site? ▼
What is the cleanup status of Koppers Co., Inc. (Oroville Plant)? ▼
About Superfund
The National Priorities List (NPL) is the list of sites of national priority among the known releases or threatened releases of hazardous substances, pollutants, or contaminants throughout the United States. The NPL is intended primarily to guide the EPA in determining which sites warrant further investigation.
The Hazard Ranking System (HRS) score is the principal mechanism the EPA uses to evaluate sites for placement on the NPL. Sites with an HRS score of 28.50 or greater are eligible for the NPL. Higher scores indicate greater potential risk.
The EPA's Superfund cleanup process typically follows these phases: preliminary assessment, site inspection, NPL listing, remedial investigation/feasibility study, remedy selection, remedial design/action, construction completion, post-construction completion, and NPL deletion. Some sites remain on the NPL for decades.
PlainEnviro presents this data without advocacy framing. The presence of a site on the NPL does not by itself indicate an immediate health risk to nearby residents. For site-specific health questions, consult your local environmental or health agency.
Read our methodology - how this data is sourced, computed, and verified.