How this site is built

An independent search layer over three public files. Not affiliated with the Colorado Division of Oil and Public Safety.

Three files, joined at 100 %

The Division publishes the facilities, the tanks and the petroleum releases as separate datasets, all keyed on facility_id. This site loads all three and joins them.

Both join rates were measured before anything was built and both are 100 %: every facility ID in the tank file and in the release file is present in the facility list. That is the cleanest chaining in this portfolio — on another state, one of the candidate keys matched 0 % and would have attached releases to nothing.

⚠️ What no page here says

That a site is polluted. None of the three files carries a concentration, a volume, a depth or an extent. Every figure here is a count, a stage or a date. What a stage actually is.

A list of facilities with unfinished cases. 506 addresses. Under such a heading they would read as a verdict on each. The counts and their distribution are published; the individual record is one search away.

Personal contact details. The release file carries a contact name, phone and email. They are not requested at download, not stored, and the loader stops if it finds them.

⚠️ Two fields handled carefully

tank_wall_type is filled on 1,013 rows of 51,987 — 2 %. It is loaded and never shown: a field that sparse on a page reads as information when it is a hole.

4,449 tank rows repeat the same facility and tank tag. They are collapsed to one physical tank each, which is why this site counts 47,538 tanks where the raw file has 51,987 rows.

Why tanks-co and not ust-co

Because Colorado publishes aboveground tanks alongside buried ones — UL142 and UL2085 vessels sit in the same file. Calling the site « underground » would be wrong in the domain name itself.

How the pages are chosen

A county gets a page at 40 facilities (56 of 65 qualify, covering 98.9%); a category at 40; a county-and-category page at 80. Cities get no page at all — a city is a subset of its county, and two pages about the same facilities is duplication by construction.

Sources

Three datasets from the Colorado Division of Oil and Public Safety on data.colorado.gov, all public domain. Our copy is from 2026-08-21. For anything a transaction depends on, use the Division’s own records.

The Division publishes these three files as public-domain open data. They record that a tank exists and that a release was reported, with the stage the case has reached — and carry no measurement of soil, water or extent. Nothing here is an environmental assessment.