Idaho Preliminary Assessment Program

The Idaho Department of Environmental Quality (DEQ) runs the Preliminary Assessment and Site Inspection Program to evaluate potentially contaminated sites and set priorities among them. DEQ says the program is carried out through a cooperative agreement between DEQ and EPA. DEQ prepares preliminary assessment and site inspection reports of mine and industrial sites, and its program page carries a table of completed assessments with links to the reports.

In a Phase I ESA

ASTM E1527-21 does not name a state preliminary assessment list among its standard record sources. DEQ's program page links EPA's Superfund site assessment process, and the federal site assessment records are described on the SEMS page. The Idaho reports still matter for a property with a mine or industrial history.

Five details shape how to read one.

• The scope is wide. DEQ says Idaho has more than 8,500 inactive and abandoned mines, mineral locations and mineral discoveries. It says the state also has abandoned or repurposed industrial facilities such as old landfills, repair and maintenance shops, dry cleaners and laundromats, rural airfields, railroad depots and manufacturers.
• An assessment is not a cleanup. DEQ says the majority of sites it assesses do not warrant remedial action based on current uses. That judgment is tied to current uses, so check it again when the planned use differs from the use at the time of the report.
• Priority goes to the worst threats. DEQ says priority is given to sites where potential contamination poses the most substantial threat to human health or the environment. Do not read the lack of a report as a finding about a site.
• The page gives the paths after a finding of risk. Where DEQ finds a substantial risk, it lists what may follow. The owner or responsible party may act voluntarily with no formal agreement. The owner may enter the Voluntary Cleanup Program. A site that a public entity is willing to own may be a candidate for the Brownfields Program. DEQ may issue a Notice of Violation under the Hazardous Waste Management Act or the Environmental Protection and Health Act. Where there is no responsible party and an imminent and substantial threat, DEQ's director may make a hazardous waste emergency declaration, which lets DEQ use emergency response funds to hire remediation specialists. If state funding is unavailable or the site falls under federal jurisdiction, the site may be placed on EPA's National Priorities List.
• Some reports come with later documents. DEQ says some listed sites also have links to engineering plans or construction completion reports for remedial action.

DEQ says a final preliminary assessment or site inspection report is usually completed within 5 to 6 months of the site visit.

DEQ notes that the listed sites are private properties and are not to be entered without the owner's permission.

Where to look a site up

• DEQ's Preliminary Assessment Program page carries a table of completed preliminary assessments. Each row gives the site name, the county, a date and a document link. Some rows show no date or no document, and some link another kind of document, such as a closure report.
• DEQ's Facility Mapper page links a map tool that has a Preliminary assessment category under Mine Sites and a separate Industrial Preliminary Assessment category.
• DEQ's program page lists a Preliminary Assessment and Remediation Project Coordinator as the staff contact. The DEQ State Office is at (208) 373-0502.

Getting the file

The reports are linked from DEQ's table. For records that are not posted, DEQ takes requests under the Idaho Public Records Act through its Public Records Request page, which carries buttons to submit a request online, track its status and search the request archives.

Sources

Idaho Department of Environmental Quality pages, read October 1, 2026:

• Preliminary Assessment Program, last modified January 7, 2026.
• Facility Mapper, last modified January 8, 2026.
• Public Records Request, last modified August 18, 2026.
• Regional Offices, last modified August 6, 2026.