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Environmental Cleanup Site Information (ECSI) Database
Site Summary Report - Details for Site ID 3810, Ames-Bancroft Mine   

This report shows data entered as of December 20, 2014 at 12:39:15 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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Site Photos
Click to View Photo Picture Date Caption Size
View Photo 05/24/2006 FIGURE 1: Mine located on a 1:250,000 USGS Topographic Map 1029 Kb
View Photo 05/24/2006 FIGURE 2: Mine located on a 7.5 minute USGS Topographic Map 915 Kb
View Photo 05/24/2006 FIGURE 3: Mine located on a 7.5 minute USGS Topographic Map 600 Kb
View Photo 05/24/2006 FIGURE 4: Mining claim (Clackamas Claim) diagrammed in 1953 U.S. Bureau of Land Management mineral survey 121 Kb
View Photo 05/24/2006 FIGURE 5: Pillow basalt outcrop near fault, southeast of mine, on south side of National Forest Road 57 1063 Kb
View Photo 05/24/2006 FIGURE 6: Wooden staircase leading down to mine from National Forest Road 57 1126 Kb
View Photo 05/24/2006 FIGURE 7: Rail track remnants and butterfly-valve-equipped vertical pipe (solidly placed) northeast of collapsed portal 1059 Kb
View Photo 05/24/2006 FIGURE 8: Collapsed mine portal northwest of staircase 1039 Kb
View Photo 05/24/2006 FIGURE 9: Overturned ore car near mine portal 999 Kb

General Site Information

Site ID: 3810 Site Name: Ames-Bancroft Mine CERCLIS No: 001002721
Address: 6S/7E-S5 Estacada 97023
  County: Clackamas Region: Northwest
Other location information: The Ames-Bancroft mining claim is located within the Mt. Hood National Forest, about 21 miles southeast of Estacada. It is located along National Forest Road 57, about 3.75 miles east of the southern terminus of State Highway 224. Lake Harriet lies about 0.56 mile east-southeast of the claim. The Clackamas River Oak Grove Fork lies about 400 feet north-northeast of the mining claim, at about 250 feet lower elevation. The Oak Grove Fork has its mouth on the Clackamas River mainstem at River Mile 53.0, about 4.2 miles downstream from the site.
Investigation Status: Suspect site requiring further investigation
Brownfield Site: No NPL Site: No Orphan Site: No Study Area: No
Property: Twnshp/Range/Sect: 6S , 7E , 5 Tax Lots: Part of Lots 10 & 11, Sect. 5
  Latitude: 45.0794 deg. Longitude: -121.9798 deg.  Site Size: 17.64 acres
Other Site Names:
  Clackamas Lode, BLM Mineral Survey #921 (1953)
  Clackamas Lode Mining Claim

Site Characteristics

General Site Description: The Ames-Bancroft mercury mine is part of a 17.6-acre patented mining claim (the Clackamas Lode Mining Claim) located along Mt. Hood National Forest Road 57, about 3.75 miles east of the southern terminus of Oregon Highway 224.

A 1953 U.S. Bureau of Land Management Mineral Survey (No. 921) depicts at least six south-trending mining, or exploration, shafts within about 75- to 200 feet north of, and downhill from, National Forest Road 57. Some of these shafts may pass beneath the road. In 1953, the route of Forest Road 57 was described simply as a trail. Oregon Department of Geology and Mineral Industries (DOGAMI) Bulletin No. 55 (Quicksilver in Oregon, by Howard C. Brooks, 1963) describes the workings on the Ames property as "scattered opencuts, all of which are caved". The DOGAMI report "presumed" that the claim was not as well mineralized as claims on the nearby Nisbet and Kiggins properties.

The Clackamas Lode Mining Claim is bounded on all sides by other unpatented mercury mining claims, including the Rainbow (east), Duane (south), Elk Horn (west), and Oak Grove (north) Lode Mining Claims; all are part of the Oak Grove Mining District. Mercury exploration pits appear to be located on each of these mining claims, based on the 1953 BLM Mineral Survey.
Site History: It is unclear when mining activities first began on the Ames-Bancroft site. George Nisbet discovered a cinnabar vein (mercury ore) extending onto the Clackamas Lode, but did not record the claim. The Ames-Bancroft group of claims was later located by A.G. Ames, who had been hired by Nisbet to do surface trenching on his Oak Grove claim. Nisbet gave the Clackamas claim to Ames and D.E. Kiggins, although Ames later acquired sole ownership. E.A. Bancroft later acquired an interest in the claim. Ames and Bancroft did not apply for a patent for the claim until 1953, although the only mercury production reported to the U.S. Bureau of Mines was for the year 1932 (7 flasks). The patent was not granted until 1958.

According to the U.S. Forest Service, all mining claims within the Oak Grove Mining District had been abandoned by 1989.

Although BLM Mineral Survey No. 921 (1953) depicts a furnace at the Ames-Bancroft mine site, and remnants of a possible furnace were observed on the site during a October 2002 field visit by DEQ and USFS. DOGAMI Bulletin No. 55 (1963) states that ore from the Ames-Bancroft mine was treated in the Vermilion Claim's furnace (at the Kiggins Mine).
Contamination Information: Likely elevated concentration of toxic metals in mining wastes. Contaminants are likely to be very similar to those encountered at the nearby Kiggins (ECSI #3812) and Nisbet (ECSI #3811) mercury mines. [ see ECSI #3811 and ECSI #3812 ]
One waste rock pile at the Kiggins mine contained mercury at a concentration that exceeded the industrial soil Hot Spot level. Two waste rock piles at the Nisbet mine contained concentrations of arsenic (4,900- and 4,570-ppm) that were more than 10 times the highest background soil concentration of arsenic (266-ppm), while the highest background soil concentration of arsenic was more than 10 times the industrial soil Hot Spot concentration (16-ppm). At least two of the background soil samples are believed to have been collected on other nearby mining claims that could also have been contaminated with mining wastes.

Metals of greatest potential human health concern are mercury and arsenic. Metals of greatest potential ecological concern include aluminum, antimony, arsenic, barium, chromium, cobalt, copper, iron, manganese, mercury, nickel, selenium, thallium, vanadium, and zinc.

Background soil (BGS-2 and BGS-3) and background vegetation (BGV-2 and BGV-3) samples that Cascade Earth Sciences (CES) collected for a March 2004 Site Inspection Report for the Kiggins and Nisbet Mine sites appear to have been collected on the Ames-Bancroft mining claim (BGS-2 and BGV-2 on the claim's Clackamas Lode; BGS-2 and BGV-3 on the claim's Elk Horn Lode). The background soil samples contained concentrations of several metals (Al, As, Ba, Cr, Co, Cu, Mn, Hg, Ni, and Ag) that appear to higher than regional background concentrations. One of the vegetation samples (BGV-3) contained aluminum at a concentration that was significantly higher than the remaining vegetation samples.
Manner and Time of Release: Distribution of metals-contaminated wastes during historic mercury mining activities.
Hazardous Substances/Waste Types: Anticipate toxic metals, predominantly mercury and arsenic. Apparent elevated concentrations of antimony, barium, berrylium, chromium, iron, lead, manganese, selenium, silver, thallium, vanadium, and zinc have also been detected in waste rock at the neighboring Kiggins and Nisbet mines.
Pathways: Mine wastes could represent a potential direct contact, incidental ingestion, or inhalation threat for site visitors.

Soil contaminants could represent a threat for plants, invertebrates, and burrowing mammals. Mercury bioaccumulates in the food chain so local predators could have higher systemic concentrations of mercury.

Contaminants appear to be present in vegetation at the neighboring Kiggins and Nisbet mine sites, so contaminated vegetation could represent an ingestion threat for invertebrates, birds, and mammals that feed on vegetation.

Most of the local mining wastes are believed to have been discharged to the river. River sediments along the Kiggins and Nisbet mine sites are known to be contaminated. Contaminated sediments are also likely to be found downstream from the mining sites. Benthic macroinvertebrates and fish within the river may also be contaminated. Elevated concentrations of mercury have been detected in fish tissue from the Clackamas River's North Fork Reservoir, 20- to 23 miles downstream from the mouth of the Oak Grove Fork. Contaminated macroinvertebrates and fish could represent a food-chain threat to terrestrial predators.
Environmental/Health Threats: Site contaminants could represent potential threats to both human health and the environment. Because mercury is persistent and biomagnifies in the food chain, it can represent a greater threat to upper trophic level species.

Contaminants have been detected in river sediments along the adjacent Kiggins and Nisbet mercury mine sites, and the populations of pollution-sensitive benthic macroinvertebrates appear to be depressed in river pool areas along the mining sites. Contaminants in stream or pond sediments could enter the food chain through amphibians, fish, or benthic macroinvertebrates.

Contaminants have also been detected in vegetation at the adjoining mining sites. Contaminated vegetation could represent a threat to chewing insects, insectivores, birds that consume seeds, or herbivorous mammals.

Oak Grove Fork watershed is one of the most important watersheds for recreational use in the Mount Hood National Forest. In 1996, USFS stated that the mercury mine area had high recreational use; gates on the mine access roads are commonly breached.

Lake Harriet is a popular camping and fishing site, but the steep, narrow river valley just downstream from Lake Harriet, as well as a lack of easy access, limit downstream sport fishing, although Oregon Dept. of Fish and Wildlife (ODF&W) has described sport fishery use of the lower 5 miles of the Oak Grove Fork as moderate. Fish may be taken on the lower stretch of the Oak Grove Fork, but catch and release rules apply upstream from Lake Harriet.

Because downstream groundwater and surface water diversions used for human consumption are located away from the river and are at higher elevation, site contaminants are unlikely to affect drinking water supplies in lower portion of the Oak Grove Fork drainage.

Upstream from its mouth, the Oak Grove Fork is lined with old growth forest that was designated in 1992 as a Critical Habitat Unit for the northern spotted owl. The northern spotted owl is a state and federal Threatened Species. Bald eagles, another state and federal Threatened Species, nest and are often observed in the area of Timothy Lake, but have not been observed nesting or roosting at Lake Harriet.

Downstream from Barrier Falls (River Mile 3.8), the Oak Grove Fork provides important spawning and rearing habitat for spring chinook salmon (federal Threatened Species), coho salmon (federal Candidate Species, state Endangered Species), and winter steelhead trout (federal Threatened Species). The Oak Grove Fork has been designated Essential Habitat for chinook and coho. Anadromous fish runs in the Oak Grove Fork are depressed. Clackamas River late run Coho is the last wild coho stock left in the Columbia River Basin.

In 2001, Portland General Electric found that rainbow trout in Clackamas River North Fork Reservoir (downstream from the Oak Grove Fork) had elevated tissue concentrations of mercury. The source or sources of the mercury contamination in fish tissue have not been determined.

Barrier Falls (variously reported as 15- to 25 feet high) generally prevents upstream migration of spawning salmonids, except for potentially incidental migration during very high flow events. The Oak Grove Fork is also historic bull trout habitat, although USFS believes that the population of bull trout in the Oak Grove Fork may be "functionally extinct".

Lake Harriet has native populations of cutthroat and rainbow trout along with introduced brown trout. Brook trout and mountain whitefish also inhabit the river. Fish have been observed passing downstream over the Lake Harriet dam during incidental high-flow events; cuthroat trout that escape downstream can become searun cutthroat (state Critical Species). The coastal cutthroat population in Lake Harriet is one of the most notable populations upstream from the Clackamas River's North Fork Dam.

Two of the abandoned mercury mine shafts have been verified as hibernacula for Townsend's big eared bat, a federal Species of Concern, and state Critical species. This is one of only two known hubernacula for the species in northwest Oregon. The Ames-Bancroft mine's Quicksilver Falls shaft is one of the recognized hibernacula, although hibernating populations in this shaft appear to be rapidly declining with time. The reason for this decline remains unclear. The other local hibernacula is in the Lower Oak Grove shaft at the Nisbet Mine. The bats are known to forage for flying insects over wetlands and streams. Contaminated insect larvae that mature into flying insects could represent a food chain threat for the Townsend's big-eared bat.

Other important species with habitat in the site vicinity include the cascade, tailed, and red legged frogs, the red tree vole, the long-legged, long-eared, and fringed myotis, the silver-haired bat, the northern goshawk, and the Harlequin duck. All of these species are federal Species of Concern. Fishers (federal T&E Candidate; state Critical species) also have habitat in the Oak Grove Fork drainage. Red-legged frogs were observed in the vicinity of the site in abundance during an ecological evaluation of the mine sites in 2004.

Wolverines (federal Species of Concern; state Threatened species) have been sighted 4 miles northeast of the site, and may have denning habitat 5 to 6 miles northeast of the site. Wolverines have home ranges of up to several hundred miles.

At least 27 neotropical migratory bird species (protected by international treaty) have been identified in the Oak Grove Fork watershed, although their populations have declined significantly over the past two decades. Over half of these species are either insectivores or birds of prey that feed on forest birds, so the site's mercury contamination could reprersent a significant threat to the food supply for neotropical migratory birds.

One of the world's two largest concentrated populations of cold-water corydalis (a federal plant Species of Concern) is found just upstream from Lake Harriet. Cold-water corydalis has not been observed downstream from the dam; is is suspected that dam construction may have substantially altered the downstream plant habitat. Tall bugbane (state T&E Candidate species) likely occurs near the site, as it is found growing along the Oak Grove Fork pipeline.
Status of Investigative or Remedial Action: (3/4/03 JMW/SAS) Federal Screening in progress.

(5/24/06, smf) US Forest Service (USFS) completed an Abbreviated Preliminary Assessment (APA) for the Kiggins Mine in April 2003, and an APA for the Nisbet Mine in May 2003. Cascade Earth Sciences (CES) completed a Site inspection for USFS for the Kiggins - Nisbet Mine Complex in March 2004. An Engineering Evaluation and Cost Analysis for remedial action at the Kiggins - Nisbet Complex was completed for USFS by CES in November 2005. CES revised the Engineering Evaluation and Cost Analysis report in May 2006. A non-time-critical removal was recommended for waste rock piles at the two mine sites.

(7/6/06, smf) Federal screening completed 7/5/06. A high priority was assigned to conducting a Site Investigation.

(9/18/09; smf) EPA completed a PA of the mine site in July 2008, concluding that further investigation of the site was warranted under CERCLA.

(8/27/09 smf) In August 2008, a USFS contractor removed 100 cubic yards of arsenic hot spot waste rock from two piles located approximately midway between the Nisbet Mine and Forest Road 57 (uphill and southwest from the Nisbet Mine). The waste piles were previously (2003) described as Nisbet Mine wastes; original samples (September 2003) from the two waste piles were designated NM-WR2 and NM-WR3. During the removal (August 2008), the waste piles were described as Ames-Bancroft Mine wastes, and designated AB-WR2 and AB-WR3.

USFS also prepared a three-year (2009-2011) post-cleanup monitoring plan for post-cleanup monitoring. Monitoring will include annual visual inspections, and surface water, sediment, pore water, and benthic macroinvertebrate samplings. An aquatic habitat survey will also be performed.
Data Sources: Abbreviated Preliminary Assessment, Kiggins, Mt. Hood National Forest, Clackamas River Ranger District, Clackamas County, Oregon, prepared by USDA Forest Service, April 2003.

Abbreviated Preliminary Assessment, Nisbet, Mt. Hood National Forest, Clackamas River Ranger District, Clackamas County, Oregon, prepared by USDA Forest Service, May 2003.

Kiggins ans Nisbet Mines, Initiation of CERCLA Investigation, Memorandum, prepared by Richard Sowa, Director of Engineering, Pacific Northwest Region, February 26, 2004.

Site Inspection Report - Final, Kiggins and Nisbet Mines, Mt. Hood National Forest, prepared for USDA Forest Service, Mt. Hood National Forest, by Cascade Earth Sciences, March 2004.

Engineering Evaluation / Cost Analysis, Kiggins - Nisbet Mine Complex, Mt. Hood National Forest, Clackamas County, Oregon, prepared for USDA Forest Service, Mt. Hood National Forest, by Cascade Earth Sciences, November 2005.

Engineering Evaluation / Cost Analysis, Kiggins - Nisbet Mine Complex, Mt. Hood National Forest, Clackamas County, Oregon, prepared for USDA Forest Service, Mt. Hood National Forest, by Cascade Earth Sciences, May 2006 (revision of November 2005 report).

Preliminary Assessment Report, Ames-Bancroft Mine, Estacada, Oregon, TDD: 07-09-0007, prepared by TechLaw, Inc. (Contract EP-S07-06-03), for USEPA Region 10, July 2008.

Non-Time Critical Action Report, Kiggins-Nisbet Mine Complex, Mt. Hood National Forest, Oregon, prepared for USDA Forest Service, Gifford Pinchot National Forest, by Millennium Science & Engineering, Inc., March 2009.

Long-Term Monitoring Plan, Kiggins-Nisbet Mine Complex, Mt. Hood National Forest, Oregon, prepared for USDA Forest Service, Gifford Pinchot National Forest, by Millennium Science & Engineering, Inc., April 2009.

Post Removal Action, Annual Monitoring Report, 2009, Kiggins-Nisbet Mine Complex, Mt. Hood National Forest, Oregon, prepared for U.S. Forest Service, Region 6, by Millennium Science & Engineering, Inc., March 2010.

Post Removal Action, Annual Monitoring Report, 2010, Kiggins-Nisbet Mine Complex, Mt. Hood National Forest, Oregon, prepared for U.S. Forest Service, Region 6, by Millennium Science & Engineering, Inc., January 31, 2011.

Brooks, Howard C., Quicksilver in Oregon, Bullentin No. 55, Department of Geology and Mineral Industries, State of oregon, pp. 105-111, 1963.

Mineral Survey No. 921, Oregon, Claim of A.G. Ames and E. A. Bancroft, U.S. Dept. of the Interior, Bureau of land Management, October 26, 1953.

Patent Approval for Clackamas Mining Claim, Patent Number 1186526, Clackamas lode mining claim, A.G. Ames and E. A. Bancroft, U.S. Bureau of Land Management, September 24, 1958.

Mercury Mines along the Oak Grove Fork of the Clackamas River, Michael O'Leary, Clark Honors College, University of Oregon, June 3, 2004.

Oak Grove Watershed Analysis, USDA Forest Service, September 1996 (Final Report).

North Fork Reservoir and Timothy Lake Mercury Analysis, Total Mercury in Clackamas River and Hatchery Fish, 2001, prepared for Portland General Electric, by Lian Liang, Cebam Analytical, Inc.

My North West Micro Mineral Study Group (NWMMSG) Report about Lake Harriet, OR, Bill Tomkins, http://members.tripod.com/~WTompkins/index-374.html

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
Closeout activities on completed project  (Primary Action) 07/02/2012 07/02/2012 Stephen Fortuna SAS
View Full Report Showing Action History

Site Environmental Controls

Control Description Begin Date End Date Last Reviewed By Last Review Date
Contamination left in place, Soil 09/29/2009   Steve Fortuna 04/04/2011
  Comments: Baseline conditions 9/29/09, report issued 3/30/10 September 2009 Monitoring Activities, report issued 3/30/10. September 2010 Monitoring Activities, report issued 1/31/11.

Key to Certain Acronyms and Terms in this Report:

  • CERCLIS No.: The U.S. EPA's Hazardous Waste Site identification number, shown only if EPA has been involved at the site.
  • Region: DEQ divides the state into three regions, Eastern, Northwest, and Western; the regional office shown is responsible for site investigation/cleanup.
  • NPL Site: Is this site on EPA's National Priority List (i.e., a federal Superfund site)? (Y/N).
  • Orphan Site: Has DEQ's Orphan Program been active at this site? (Y/N). The Orphan Program uses state funds to clean up high-priority sites where owners and operators responsible for the contamination are absent, or are unable or unwilling to use their own resources for cleanup.
  • Study Area: Is this site a Study Area? (Y/N). Study Areas are groupings of individual ECSI sites that may be contributing to a larger, area-wide problem. ECSI assigns unique Site ID numbers to both individual sites and to Study Areas.
  • Pathways: A description of human or environmental resources that site contamination could affect.
  • Lead Pgm: This column refers to the Cleanup Program affiliation of the DEQ employee responsible for the action shown. SAS or SAP = Site Assessment; VCS or VCP = Voluntary Cleanup; ICP = Independent Cleanup; SRS or SRP = Site Response (enforcement cleanup); ORP = Orphan Program.

For more information on this site contact the Northwest regional office.

[print version]

For more information about ECSI call Gil Wistar at 503-229-5512 or email.

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