California environmental cleanup sites by ZIP code
The State Water Board's GeoTracker lists 9,918 open cleanup cases in California, in four groups: Cleanup Program sites (the largest group), leaking underground storage tanks (about one open case in eight), land disposal sites and military cleanups. Enter a ZIP code to see how many are open there, then search the property itself in GeoTracker before you buy.
Open cleanup cases in a ZIP code
1,330 California ZIPs have at least one open case. Counts under 5 are shown as “<5”. About one open case in eight carries no ZIP and is counted only in the county table below.
Key findings
California has 9,918 open environmental cleanup cases in the State Water Board's GeoTracker system, led by Los Angeles (1,852), Alameda (840) and Kern (783).
Open leaking underground storage tank, Cleanup Program, land disposal and military cases from the GeoTracker export of 2026-11-03. A count says nothing about any specific parcel.
Data: GeoTracker export 2026-11-03. Link to this finding
Source: State Water Resources Control Board, GeoTracker. Computed from our dataset “Open environmental cleanup cases by county (GeoTracker)” (version 2026-11-04); download the CSV. Free to reuse under CC BY 4.0 with a link to this page. Findings update when the data does.
How to check a California property yourself
- Search the address in GeoTracker (State Water Board): use the map to see cases on and near the parcel.
- Search it in EnviroStor (Department of Toxic Substances Control), which covers hazardous-substance cleanups GeoTracker may not.
- Open each nearby case: its status (definitions below), the contaminants, and the case documents, including any closure letter and land-use restrictions.
What a count does not tell you
A ZIP or county count says nothing about whether a specific parcel is affected. Only the case records on and near the parcel answer that question.
Open cleanup cases by county
| County | Open cases | Leaking tanks (LUST) | Cleanup Program | Land disposal / military |
|---|---|---|---|---|
| Los Angeles | 1,852 | 260 | 1426–1429 | 152–185 |
| Alameda | 840 | 167 | 570 | 92–125 |
| Kern | 783 | 10–19 | 66–69 | 700–718 |
| Sacramento | 656 | 21–27 | 484–487 | 134–170 |
| San Diego | 517 | 45–48 | 221–230 | 234–270 |
| Santa Clara | 516 | 35 | 440 | 31–67 |
| San Bernardino | 465 | 27–36 | 93–96 | 332–359 |
| Orange | 395 | 111 | 206–212 | 71–89 |
| Santa Barbara | 328 | 4–16 | 231–234 | 88–109 |
| San Joaquin | 279 | 33–36 | 118–124 | 120–141 |
| San Mateo | 250 | 31–37 | 201–204 | 12–30 |
| Contra Costa | 234 | 36–42 | 102–108 | 81–108 |
| Ventura | 213 | 8–14 | 69 | 125–152 |
| San Francisco | 201 | 17–29 | 58–61 | 107–143 |
| Sonoma | 175 | 43–46 | 84–90 | 38–56 |
| Riverside | 172 | 37–40 | 40–49 | 80–113 |
| Solano | 151 | 4–16 | 34–40 | 96–126 |
| Fresno | 127 | 16–22 | 70–79 | 28–40 |
| Humboldt | 113 | 7–13 | 43–52 | 50–59 |
| Imperial | 99 | 21–27 | 2–8 | 57–87 |
| Santa Cruz | 97 | 3–12 | 85–88 | 3–12 |
| Mendocino | 91 | 21–24 | 25–37 | 32–50 |
| Merced | 88 | 10–19 | 43–52 | 25–46 |
| Monterey | 84 | 8–17 | 27–39 | 34–46 |
| Stanislaus | 83 | 4–16 | 36–45 | 34–55 |
| Tulare | 80 | 8–17 | 32–41 | 29–38 |
| San Luis Obispo | 73 | 1–4 | 46–58 | 18–27 |
| Yuba | 71 | 3–12 | 9–15 | 53–68 |
| Placer | 67 | 3–12 | 30–42 | 26–59 |
| Marin | 64 | 11–20 | 15–33 | 25–52 |
| Yolo | 64 | 3–12 | 39–42 | 19–31 |
| Siskiyou | 56 | 3–12 | 12–21 | 33–42 |
| Kings | 48 | 2–8 | 11–26 | 13–48 |
| Shasta | 46 | 4–16 | 19–34 | 15 |
| Lassen | 41 | 4–16 | 5–20 | 25–37 |
| Nevada | 35 | 4–16 | 9–21 | 14–23 |
| Sutter | 34 | 3–12 | 17–29 | 12–15 |
| Butte | 33 | 6–9 | 18–33 | 3–12 |
| Napa | 32 | 4–16 | 15–24 | 2–8 |
| Colusa | 30 | 1–4 | 8–17 | 18–27 |
| Madera | 30 | 1–4 | 17–30 | 9–18 |
| Trinity | 30 | 2–8 | 9–15 | 18–27 |
| Inyo | 29 | 1–4 | 1–4 | 19–29 |
| El Dorado | 27 | 2–8 | 14–27 | 2–8 |
| Tuolumne | 24 | 3–12 | 8–14 | 11–14 |
| Amador | 23 | 5 | 2–8 | 10–16 |
| Glenn | 22 | 1–4 | 4–16 | 10–22 |
| Sierra | 20 | 1–4 | 1–4 | 18–20 |
| Calaveras | 19 | 3–12 | 1–4 | 13–19 |
| Lake | 19 | 2–8 | 5–19 | 5–19 |
| Del Norte | 18 | 1–4 | 7–10 | 8–14 |
| Modoc | 18 | 2–8 | 3–12 | 8–17 |
| San Benito | 13 | 0 | 4–13 | 3–12 |
| Tehama | 13 | 0 | 3–12 | 3–12 |
| Plumas | 12 | 1–4 | 5–12 | 2–8 |
| Mariposa | 10 | 2–8 | 2–8 | 3–10 |
| Mono | 8 | 0 | 1–4 | 4–8 |
| Alpine | <5 | 0 | 2–4 | 1–4 |
Open = every status beginning “Open”. Where a type includes small counts withheld as “<5”, the figure is shown as a range. Permits and projects (NPDES, waste discharge, cannabis and similar) are not cleanup cases and are left out. Download: cleanup-cases-by-county.csv.
What each case status means
GeoTracker's own definitions (Project Status Definitions):
- Open – Site Assessment
- “Site characterization, investigation, risk evaluation, and/or site conceptual model development are occurring at the site.”
- Open – Assessment & Interim Remedial Action
- “An 'interim' remedial action is occurring at the site AND additional activities such as site characterization, investigation, risk evaluation, and/or site conceptual model development are occurring.”
- Open – Remediation
- “An approved remedy or remedies has/have been selected for the impacted media at the site and the responsible party (RP) is implementing one or more remedy under an approved cleanup plan for the site.”
- Open – Verification Monitoring
- “Remediation phases are essentially complete and a monitoring/sampling program is occurring to confirm successful completion of cleanup at the Site.”
- Open – Long Term Management
- “Remediation phases are complete, all current risks to receptors are mitigated, and risk management measures are in place.”
- Open – Eligible for Closure
- “Corrective action at the Site has been determined to be completed and any remaining petroleum constituents from the release are considered to be low threat … The case in GeoTracker is going through the process of being closed.”
- Open – Inactive
- “No regulatory oversight activities are being conducted by the Lead Agency.”
- Completed – Case Closed
- “A closure letter or other formal closure decision document has been issued for the site.”
Land disposal sites use other statuses (for example “Open – Operating”) that this document does not define; they are shown as GeoTracker labels them.
Frequently Asked Questions
What is GeoTracker?
GeoTracker is the California State Water Resources Control Board's public data system for sites that affect, or could affect, water quality, including leaking underground storage tank cases, Cleanup Program sites, land disposal sites and military cleanups. Anyone can search it by address or map, free.
How do I check a California property for contamination cases?
Search the address in GeoTracker (State Water Board) and in EnviroStor (Department of Toxic Substances Control), which covers hazardous-substance cleanups. Look at cases on and near the parcel, their status, and the case documents. The ZIP counts on this page only show how many open cases a ZIP has; they do not say whether any parcel is affected.
What does an open cleanup case mean?
Open means the case has not been formally closed. The status says where it is: for example "Open – Site Assessment" (investigation is happening), "Open – Remediation" (an approved cleanup is under way) or "Open – Eligible for Closure". The definitions on this page are GeoTracker's own.
Is a closed case a clean site?
"Completed – Case Closed" means a closure letter or other formal closure decision was issued. A closed case can still carry land-use restrictions, so read the closure document in the case record before relying on it.
Source: State Water Resources Control Board, GeoTracker cleanup sites data download, accessed 2026-11-03. Counts are derived from the public export; no site names, addresses or identifiers are republished.