Contaminated and cleanup sites near California properties
Three government lists record sites with known or suspected contamination in California. This guide explains what each list is, how Outpost uses them, and what a nearby listing does and doesn’t tell you.
In short
- Outpost maps EPA Superfund (National Priorities List) sites, DTSC EnviroStor sites and leaking underground storage tank (LUST) cleanup sites from the State Water Board.
- The scorecard lists any of these sites within 500 feet of a point.
- A nearby listing doesn’t mean a property is contaminated. The agency’s record has the details and status.
- Records that Outpost identifies as having only an approximate location are never counted.
Screening only — not a legal or official determination. Verify with the issuing agency.
The three lists
- Superfund National Priorities List (U.S. EPA): EPA’s list of national-priority sites among the known or threatened releases of hazardous substances. EPA uses it mainly to decide which sites need further investigation.
- EnviroStor (California Department of Toxic Substances Control): DTSC’s cleanup and investigation site records. Outpost includes EnviroStor cleanup and investigation records of every type and status, from active cleanups to closed cases such as “No Further Action”, as well as school and military evaluations. EnviroStor’s list of permitted hazardous waste facilities isn’t included.
- Leaking underground storage tanks (State Water Resources Control Board): sites from a Water Boards public map layer of leaking tank cleanup sites. The layer doesn’t describe how its sites were chosen; it is a subset of the cases in GeoTracker, the Water Boards’ system for sites that affect or could affect water quality, especially groundwater. GeoTracker lists many more leaking tank cases, including closed ones.
Outpost’s current data has 99 Superfund sites, 13,387 EnviroStor records and 694 leaking tank cleanup sites from that Water Boards layer.
Approximate locations
Some records give only a rough location, such as a city’s center point or coordinates rounded to a coarse grid. Outpost looks for these (points on a coarse grid, one point shared by different sites, and the center of the state) and doesn’t count the ones it finds in the 500-foot checks. It can’t catch every one, and a few precise points that happen to fall on the grid are left out too. On the map, records rounded to within half a mile are drawn as hollow rings; city centers and coarser points (including a few large Superfund sites) aren’t shown. Look those up with the agency.
Why it matters
A nearby listed site is worth reading about before you buy: the agency’s record says what was found and where the case stands. For commercial and land purchases, buyers and lenders often commission a Phase I environmental site assessment. A nearby leaking tank can matter if you plan to rely on a private well, because groundwater may be affected.
How to check a location on Outpost
- Search the property’s address on the map, or click its location.
- The scorecard’s environmental hazards section lists each Superfund, EnviroStor and leaking tank site within 500 feet of the point, with its name and address, and for EnviroStor its type and status.
- To see the sites, turn on the Federal Superfund (NPL), State Response (EnviroStor) and Leaking Tanks (LUST) layers.
- Federal Superfund (NPL)
- State Response (EnviroStor)
- Leaking Tanks (LUST)
- Approximate location
What Outpost can’t tell you
- Whether a particular parcel is contaminated.
- A case’s current status or severity. Open the agency record. For EnviroStor sites Outpost shows the status as of its data date; the Superfund and leaking tank data carry no status.
- Large sites: each site is one point in the data, and a big site can extend well beyond 500 feet from its point.
- Leaking tank cases missing from that Water Boards layer. Search GeoTracker for the full list.
- Sites on other lists, and sites Outpost identifies as having only an approximate location.
Common questions
How do I find contaminated sites near an address?
Search the address on Outpost and turn on the three site layers, or search each agency’s own tool: EPA’s Superfund site search, DTSC’s EnviroStor and the Water Boards’ GeoTracker.
Does a site within 500 feet mean my property is contaminated?
No. It means a listed site is nearby. The agency’s record describes the case and its status. For commercial or land purchases, buyers and lenders often commission a Phase I environmental site assessment.
What is the difference between EnviroStor and GeoTracker?
EnviroStor is DTSC’s system for cleanup, investigation and hazardous waste sites. GeoTracker is the Water Boards’ system for sites that affect or could affect water quality, including leaking underground storage tanks.
Why are some sites hollow rings?
Their location is only approximate (rounded to within about half a mile), so Outpost draws them as rings and doesn’t count them as nearby.
Official sources
- U.S. EPA: Superfund National Priorities List
- U.S. EPA: Search for Superfund sites where you live
- California DTSC: EnviroStor
- California State Water Resources Control Board: GeoTracker
Related guides
- California groundwater basins and SGMA priority
What DWR’s SGMA basin priorities and critically overdrafted basins mean for wells and land in California, and how to see which basin a location is in.
- FEMA flood zones in California
What FEMA flood zones A, AE, V, X and D mean, when flood insurance is usually required, and how to check a California location for free.
- Data sources
Every map layer and scorecard check on Outpost and the agency behind it: CAL FIRE, FEMA, CGS, USFWS, DWR, EPA, DTSC, the State Water Board and more.