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States / Washington

Okanogan County, WA

The federal environmental record for Okanogan County (population 43,712): what is on file, where it is, and what remains open. Sources and retrieval dates are on the methodology page.

1

Superfund NPL sites

17

federal cleanup sites

1

PFAS-detecting water systems

0

TRI facilities

10

open tank releases

Superfund NPL sites

SiteCityStatusListed
Silver Mountain MineLoomisdeleted06/10/1986

Drinking water: PFAS testing

Public water systems serving Okanogan with at least one PFAS detection under UCMR5. The federal limit for PFOA and PFOS is 4 ng/L; EPA proposed in May 2026 to rescind the limits for the other compounds, which are shown for information.

SystemHighest resultsReading
OMAK CITY OF

WA5363750

PFPeA: 3.4 ng/L

detected

On a system with detections? Testing and treatment options

Underground fuel tanks

EPA's UST Finder records 193 tank facilities in Okanogan: 92 tanks in service and 417 closed. 20 fuel releases are on record, of which 10 remain open. Open releases are cleanups that have not reached "no further action".

Radon

EPA maps Okanogan as Zone 1, the highest predicted indoor radon levels (over 4 pCi/L average). Radon and air quality are covered in depth on lung.com.

The record for one specific address

County figures blur what matters: distance. The Address Environmental Report runs these same federal datasets against one address and reports every site, tank, polluter and water result around it, with distances, in about a minute.

Get the report - $39

All federal cleanup sites on file

The wider Superfund enterprise inventory (SEMS) for Okanogan, including sites assessed but never listed. Presence here records that EPA had reason to look, not a finding of danger.

  • ALDER MILLTWISP
  • ALDER MINETWISP
  • AZURITE MINEMARBLEMOUNT
  • FS-OKANOGAN-WENATCHEE NF, NORTH CASCADES SMOKE JUMPER BASEWINTHROP
  • SILVER MOUNTAIN MINELOOMIS
  • US DOI BLM OROVILLE LDFLOROVILLE
  • USDA FS OKANOGAN NF:ALDER CRKTWISP
  • USDA FS OKANOGAN NF:KERRCONCONULLY
  • USDA FS OKANOGAN NF:MINNIE MINETWISP
  • USDA FS OKANOGAN NF:TONASKETTONASKET
  • USDA FS OKANOGAN-WENATCHEE NF: LOWER WINTHROP COMPOUNDWINTHROP
  • USDA FS OKANOGAN-WENATCHEE NF: BETH LAKE PROSPECTCHESAW
  • USDA USFS R06 EIGHT MILE RANCH OKANOGAN NATIONAL FORESTWINTHROP
  • USDA USFS R06 OKANOGAN NF BONAPARTETONASKET
  • USDA USFS R06 OKANOGAN NF LOST LAKEOKANOGAN
  • USDOI BLM ENLO POWERHOUSE AKA SIMILKAMEEN RIVER SITEOROVILLE
  • USDOI BLM KABBA TEXAS MINELOOMIS