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Environmental Cleanup Site Information (ECSI) Database Site Summary Report - Details for Site ID 2491, Opalite Mine

This report shows data entered as of May 16, 2021 at 5:07:58 AM

This report contains site details, organized into the following sections: 1) Site Photos (appears only if the site has photos); 2) General Site Information; 3) Site Characteristics; 4) Substance Contamination Information; 5) Investigative, Remedial and Administrative Actions; and 6) Site Environmental Controls (i.e., institutional or engineering controls; appears only if DEQ has applied one or more such controls to the site).  A key to certain acronyms and terms used in the report appears at the bottom of the page.

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Environmental Cleanup Site Information (ECSI) Database Site Summary Report - Details for Site ID 2491, Opalite Mine

Site Photos
Click to View Photo Picture Date Caption Size
View Photo 02/18/2021 Mercury vapor monitoring during EPA Removal 2020 76 Kb
View Photo 02/18/2021 Installing gate during EPA Removal 2020 91 Kb
View Photo 02/18/2021 Disposing highly contaminated tailings in on-site repository during EPA Removal 2020 122 Kb
View Photo 02/18/2021 Excavating highly contaminated tailings during EPA Removal 2020 90 Kb
View Photo 02/18/2021 Re-routing road around contaminated area during EPA Removal 2020 77 Kb
View Photo 02/18/2021 Gate and signs to detur trespass into contaminated area during EPA Removal 2020 61 Kb
View Photo 02/18/2021 Fencing and signs to detur trespass into contaminated area during EPA Removal 2020 95 Kb
View Photo 03/24/2004 Site Sign 2491 3-24-2004 76 Kb
View Photo 06/06/2000 2491 6-6-2000 72 Kb
View Photo 06/06/2000 2491 6-6-2000 93 Kb
View Photo 06/06/2000 Tailings pile at the Opalite. 2491 6-6-2000 90 Kb
View Photo 06/06/2000 View of Opalite looking south. 2491 6-6-2000 84 Kb
View Photo 06/06/2000 Retorts at Opalite. 2491 6-6-2000 85 Kb
View Photo 06/06/2000 Opalite Mine. 2491 6-6-2000 84 Kb
View Photo 10/01/2004 Sampling at McDermitt Creek 331 Kb
View Photo 10/01/2004 Sampling at Hot Creek 327 Kb
View Photo 10/01/2004 Cowboy creek w/ Calcine piles in background 376 Kb

General Site Information

Site ID: 2491 Site Name: Opalite Mine CERCLIS No: SFN1002255
Address: 40S/40E/S33 McDermitt 
  County: Malheur Region: Eastern
Other location information: 7 miles by road west of McDermitt
Investigation Status: Suspect site requiring further investigation
Brownfield Site: No NPL Site: No Orphan Site: Yes Study Area: No
Property: Twnshp/Range/Sect: 40S , 40E , 33 Tax Lots: 700; Mineral Survey 854
  Latitude: 42.0525 deg. Longitude: -118.0335 deg.  Site Size: 342 acres
Other Site Names:

Site Characteristics

General Site Description: The Opalite Mine is an inactive mercury mine located on a patented mining claim that is surrounded by public land administered by the Bureau of Land Management (BLM). It is located in the extreme southern end of Malheur County Oregon, approximately 15 miles northwest of McDermitt, Nevada. The area is within the Vale District of the BLM. The climate of the area is arid, and the sparse vegetation consists of grasses, sagebrush, and other shrubs. Willows and other woody vegetation is present along many of the local creeks. The site is about 5,400 feet above sea level, approximately 342 acres in size, and consists of a mine pit, shaft, adits, several small exploratory prospect excavations, several waste rock piles, remains of processing facilities, and two large piles of processed ore. Mine Creek flows in a southerly direction along the south side of the site. Adjacent land use mainly consists of livestock grazing. There are no residences or other structures within 4 miles of the site. Access to the site is unrestricted.
Site History: OWNERSHIP AND OPERATIONAL HISTORY: The Opalite deposit was discovered by William Bretz in 1924. In April 1925, F.W. Bradley formed the Mercury Mining Syndicate and developed the Opalite Mine. Processing facilities were constructed in 1926 (Schuette, 1938). The Opalite Mine produced a total of 12,367 flasks of mercury (a flask is equivalent to 76 pounds) between 1927 and 1961, with the vast majority of the production occurring before 1943. Only spotty production was recorded between 1944 and 1961 (Brooks, 1971). Current Malheur County Tax records indicate that Bradley Mining Company of San Francisco, California owns the site. The Bradley Mining Company also owned and operated the Bretz Mercury Mine (ECSI #2493), located approximately 6 miles east of Opalite. Most of the ore produced at Bretz was processed at Opalite. REGULATORY HISTORY: Other than regulation of mining claims in the site vicinity by the BLM, there appears to be no regulatory history at the site. The significant mining operations that have occurred pre-date most state and federal mining regulations.
Contamination Information: (2/22/00 MMR/SAS) Characteristic mercury contamination from mining and processing operations. The ore grade was 6 to 40 lb/ton. Ore from Opalite was processed in a furnace at the Opalite Mine. Large burned-ore piles are in evidence on site maps. (3/12/01 JPD/SAS) Several areas of concern were identified at the site during a 6/00 visit by Oregon Department of Environmental Quality DEQ staff: Burned Ore Piles - The most striking features of the Opalite Mine site are the two large burned ore piles located on either side of the processing facilities. These piles are particularly large due to the fact that most of the ore from the nearby Bretz Mine was processed at this site. A sample collected from one of the burned ore piles during the site visit contained 21.8 mg/kg total mercury. Ore Processing Facilities - The remains of substantial ore processing retort ovens are present in the central portion of the site. Due to the concentration processes that were conducted, it is expected that this area would have the highest mercury concentrations at the site. Open Pit - A large open mine pit is present at the site. This area contains exposed mineralized material, which may be a source of mercury contamination and possible Acid Rock Drainage (ARD). There are no surface water run-on/off controls in the pit area. Mine Adits/Shafts and Associated Waste Rock- There are at least one shaft and one adit (horizontal mine tunnel opening) present at the site. These could be a source of ARD; however no evidence of water drainage was observed during the site visit. The waste rock associated with the mine workings is also a potential source of ARD and mercury contamination. A soil sample collected at the observed adit contained 478 mg/kg mercury. Stream Sediment- One stream sediment sample was collected in Mine Creek about 0.75 mile downstream of the site. Water was flowing in the stream and small fish (species not determined) were observed. The location is at a fence line that appears to be the southern boundary of the private land at the site. The total mercury concentration in the sediment sample was 110 mg/kg.

(3/26/03 JPD/SAS) Results of SI conducted by EPA contractor indicate moderate total mercury levels at site: a maximum of 792 ppm in the mine pit, and less than 100 ppm in burned ore. Burned ore is high in arsenic - over 1,000 ppm. Mercury levels in stream sediment much lower than DEQ sample - max. of 4.3 ppm total mercury in Mine Creek.
Manner and Time of Release: Mercury mining and processing operations from 1926 to 1961. Mining ended in 1943, but processing/cleanup for the Opalite and Bretz mines continued until 1961.
Hazardous Substances/Waste Types: Mercury ore and processing waste.
Pathways: The site is located in or near sensitive Lahontan Cutthroat Trout habitat as identified by DEQ GIS data.
Environmental/Health Threats:
Status of Investigative or Remedial Action: (2/22/00 MMR/SAS) Site discovery February 2000. Site screening, information request pending.

(3/26/03 JPD/SAS) Further sampling in support of Risk Assessment needed. Need surface water and fish tissue data, along with mercury speciation data in source areas.

(2/17/05 JPD/SAS) In December 2003 and June 2004, DEQ’s Contractor, Ecology & Environment, Inc. (E&E), conducted a focused site investigation at the Opalite Mine to address data gaps related to human health and environmental receptors and physical hazards present at the mine. The focused SI included sampling surface and subsurface soil samples, surface water and seep samples, sediment samples, and hydrologic measurements to evaluate environmental conditions at the site representative of the late fall, low water flow timeframe and the spring, high water flow timeframe. A review of the site data indicate that elevated metals are present in soil, sediment, surface water, and possibly groundwater. Concentrations of metals currently exceed human health and ecological screening criteria, although additional work is necessary to quantify the risk posed by the site. Physical hazards identified during the SI (open shafts, adits, seeps) will be fenced and signs installed to help address and to prevent possible unintended human accidents and injuries.

2/18/21 - BET - EPA complted a Removal at the site in August 2020. The Removal consisted of nistalling gates, fending, and signage, and rerouting a main road that traveled through the center of contamination. The removal also included disposal of highly contaminated tailings in an on site repository.
Data Sources: Quicksilver Deposits in Oregon, Howard C. Brooks, miscellaneous Paper 15 Malheur County Assessment Office, DOGAMI Bulletin # 55 & #4, Map Tech, 7.5 min quadrangle

Substance Contamination Information

Substance Media Contaminated Concentration Level Date Recorded
No information is available

Investigative, Remedial and Administrative Actions

Action Start Date Compl. Date Resp. Staff Lead Pgm
REMOVAL  (Primary Action) 07/01/2019 08/01/2020 Bryn Thoms
View Full Report Showing Action History

Key to Certain Acronyms and Terms in this Report:

You may be able to obtain more information about this site by contacting Bryn Thoms at the Eastern regional office or via email at If this does not work, you may contact Ximena Cruz Cuevas (503) 229-6811, or via email at or contact the Eastern regional office.