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In September 1995, the Fort Belknap Community Council petitioned the Agency for ToxicSubstances and Disease Registry (ATSDR) to evaluate two large, open-pit, cyanide heap leaching,gold mines located adjacent to the south end of the Fort Belknap Reservation. The council believedthe mines posed a health hazard to the people of the reservation by releasing toxic substances intothe environment, especially into drinking water supplies. Concerns were raised by communityresidents in the petition letter and subsequent meetings with ATSDR representatives about thequality of the drinking water and pollution of surface water, sediments, and air on the reservation.During November 1995, ATSDR conducted a site visit to Fort Belknap Reservation to meet withthe Fort Belknap Community Council about its concerns and then again in 1996 to conduct publicavailability sessions in Hayes, Lodge Pole, Landusky, Agency, and Malta. The results of theagency's evaluation of the concerns expressed by the petition were presented to the Fort BelknapCommunity Council in May 1996.

Data from the drainages flowing in the direction of Fort Belknap and groundwater were reviewed todetermine what contaminants were present at concentrations above the ATSDR comparison values.ATSDR identified a past completed pathway of exposure to lead in drinking water from someprivate wells. The levels detected do not pose a health threat, and subsequent sampling failed toshow any lead contamination. Private well water has elevated levels of naturally occurring salts andminerals, however the levels are not expected to cause adverse health effects.

Based on the data reviewed, ATSDR concludes that the gold mining operations are no apparentpublic health hazard to the residents of Fort Belknap. Additional studies of the groundwater andsurface water are planned. These data will be useful in evaluating potential future exposurepathways.

ATSDR supports the planned community health evaluation and recommends that any additionalenvironmental data collected utilize analytical methods that would permit detection of substances ator below known health-based comparison values. If requested, ATSDR will review any additional environmental or health outcome data provided.


This public health assessment (PHA) summarizes the environmental and health outcome dataprovided to ATSDR, and responds to community concerns expressed to ATSDR staff, since thepetition was received. This public health assessment is not a medical examination nor a community health study. It is a review of information about hazardous substances at the site and it evaluates whether exposure to those substances might cause any harm to people.


A. Historical Setting

Fort Belknap was established in 1869 near the present town of Chinook, Montana. The new fortserved as a trading post and became the government agency for the Gros Ventre and AssiniboineIndians living in the area. On May 1, 1888, a congressional act set aside the land for the FortBelknap Reservation. Later that year, the agency moved from Chinook to its present location 5miles east of Harlem, on the northwest corner of the reservation.(Indian Claims Commission,Undated). Also, during 1888, lode gold was found in the Little Rockies shortly after the FortBelknap Reservation was founded.

In 1895, a congressional commission was sent to Fort Belknap to negotiate the purchase of the LittleRockies from the tribes. The Gros Ventre and the Assiniboine vehemently opposed the "sale of themountains," which was advocated by federal commissioners who were assigned to negotiate the saleof the gold mining country in 1896 (Indian Claims Commission, Undated). The Assiniboine andGros Ventre representatives were told by the commissioners that they would no longer be provided"beef, cattle, flour, wagons, or anything else" if they did not sell a strip of land, 7 miles long and 4miles wide for $360,000. Eventually an agreement was reached on October 9, 1895, which sold thesouthern portion of the Little Rockies to the United States (Grinnell Agreement, 1896).

B. Creation of King Creek tailings

The mining for gold and silver in the Little Rocky Mountains (Little Rockies) of Montana began in1884 (Morrison Knudsen, 1993a) as placer operations (Indian Claims Commission, Undated).Between 1884 and the 1930s, mining in the Little Rockies involved removal of the ore-bearing rockand transportation to area mills (Morrison-Maierie Inc., 1979) resulting in the production of minetailings. The mining in the King Creek drainage took place at the August and Little Ben mines.Initially, gold mining involved crushing the ore-bearing rock and transporting it to a mill forleaching of the precious metals with a weak cyanide solution. However, in the 1930s, a 150-ton milland cyanide leaching plant were built and began operating at the Little Ben Mine. The millproduced 150 tons of ore crushed to 10 mesh daily (Morrison Knudsen, 1993a). Tailings from this mill were deposited in the headwaters of King Creek.

C. Migration of tailings in King Creek drainage

The mill tailings located in King Creek (see map of surface water drainages, Appendix A) did notpose a problem until sometime in the 1960s, when sedimentation from the tailings increasednoticeably. The deposition of large amounts of tailings within the stream adversely affected fish andwildlife habitats in the Little Peoples Creek drainage. It also resulted in siltation of irrigationequipment located at the mouth of Mission Canyon (Morrison-Maierie Inc., 1979). In 1979 thetailings extended from the headwaters where they had been initially deposited (approximately 1.5miles north of the town of Landusky, Montana) to a location in the Little Peoples Creek drainagenear Hays (Morrison-Maierie Inc., 1979). Included in this stretch of the creek are cultural andrecreational areas used by the Assiniboine and Gros Ventre Indian tribes of the Fort BelknapReservation.

Since 1979, a number of activities have changed the quantity and location of the tailings in the LittlePeoples Creek drainage. During the 1980s, Zortman Mining Inc. (ZMI) removed about 75% of theold mill tailings from the King Creek drainage for use at its current operation (DOI, 1996). In July1993, a flood resulting from unusually heavy rainfall, sent King Creek waters flowing over theCumberland Dam spillways. The beaver dams located further down the King Creek drainage werewashed out releasing tailings that were previously contained by the beaver dams (MorrisonKnudsen, 1993b). The amount of tailings that moved and the ultimate resting place is not known.

Later in 1993, ZMI removed the remaining tailings from above the Cumberland Dam (DOI, 1996).Thus, the only tailings remaining in the Little Peoples Creek drainage are the unknown quantity thatwashed downstream of the Cumberland Dam into Fort Belknap.

The U.S. Environmental Protection Agency (EPA) , Region VIII, conducted a PreliminaryAssessment and Site Investigation for the King Creek Mine Tailings Site (Morrison Knudsen, 1993a& 1993b); these activities are used to rank sites for inclusion on the National Priorities List (NPL). To date, EPA has not proposed the Fort Belknap site for inclusion on the NPL.

D. Modern cyanide heap leach gold mining

Modern, large-scale, heap leach gold mining has taken place since 1979 at the Landusky andZortman mines operated by ZMI, a subsidiary of Pegasus Gold Corporation. Both the Zortman andLandusky operations are open-pit gold mines that utilize heap leaching of gold ore with a cyanidesolution. Gold is recovered from the cyanide solution using either zinc precipitation or carbon adsorption methods (DOI, 1996).

E. Releases from the Zortman and Landusky mines

There have been several releases from the Zortman and Landusky mines.

  • A leach pad pipe broke in 1982, causing the release of about 50,000 gallons of cyanidesolution into Alder Gulch. Following the spill, cyanide was detected in the Zortmantrailer court water supply, which consisted of a cistern located in the alluvial streamchannel of Alder Gulch. As a result, ZMI had a community well drilled that nowsupplies the entire Zortman community (Pegasus Gold, 1993).
  • Ore slippage in 1985 on the 85-86 heap leach pad resulted in a breach of the liningsystem, resulting in loss of cyanide solution. Low concentrations of cyanide were thendetected in Ruby Gulch (Pegasus Gold, 1993).
  • The Landusky barren cyanide solution pond experienced a liner leak in 1988 andcyanide was detected in a monitoring well adjacent to the pond (Pegasus Gold, 1993).
  • A seam failure occurred on a new process pond liner, which was installed for ZMI in1993 by a third party contractor, leading to a release of cyanide. As a result of therelease, ZMI monitored private wells in Landusky. No cyanide was reported to bedetected in those samples (ATSDR, 1995a).
  • All of these releases occurred at locations on the south side of the mining areas that drain towards the south, away from the Fort Belknap Indian Reservation.

F. Legal actions

A lawsuit was filed August 30, 1993, by the Montana Department of Health and EnvironmentalScience (MDHES), which is now the Montana Department of Environmental Quality (MDEQ),Division of Water Quality, against Pegasus Gold and ZMI for violations of the Montana CleanWater Act (EPA, 1996). Eventually EPA and several groups from the reservation (the Gros VentreTribe, the Assiniboine Tribe, the Fort Belknap Community Council, and a citizens group known asthe Island Mountain Protectors [IMP]) joined this lawsuit. On July 22, 1996, a settlement wassigned by all the parties. The settlement provided for $4.5 million in penalties to be paid to EPA andthe state of Montana, as well as a partial cash settlement with the tribes and several supplementalenvironmental projects (SEPs), including a community health evaluation, an aquatic study, andimprovements to the drinking water systems at Hays and Lodgepole on the Fort BelknapReservation. The settlement also included requirements for a Ground Water Study Plan, which willprovide the information needed to determine whether there are impacts from mine wastewater on thearea groundwater. The defendants (ZMI, etc.) also agreed to provide a bond or surety totaling $32.3 million to the state of Montana to cover the costs of long-term water treatment (EPA, 1996).

G. Mine Expansion

On May 11, 1992, ZMI proposed an expansion of mining operations at the Zortman Mine in theLittle Rockies. The proposal included expanding the existing mine pits to include the developmentof sulfide ore deposits. This will require construction of new facilities including a waste rockdisposal area, crushing facilities, a leach pad, a new processing plant and ponds, and a limestonequarry (DOI, 1996). A draft environmental impact statement (EIS) was released in August 1995and the final EIS was released by the MDEQ and the U.S. Department of Interior, Bureau of LandManagement (BLM), in March 1996. The EIS addresses major environmental impacts and issuesassociated with the proposed expansion of both the Zortman and Landusky mines (DOI, 1996). Therecord of decision was released October 1996 approving the expansion of the mines as described in the preferred alternative (Alternative 7) of the final EIS.

H. Past ATSDR Activities

In October 1992, ATSDR was requested to conduct a health consultation to address health concernsamong the population at the reservation related to the mine tailing contamination in King Creek.Three consultations were completed; they are summarized below (see Appendix B for the complete documents).

  • The first two consultations concluded that the health of residents of the Fort Belknap IndianReservation was not being adversely impacted by contaminants in groundwater, surface water,or sediment in King Creek or other creeks in the areas. However, water from some private wellscontained high concentrations of sulfate, iron, total dissolved solids (TDS), and other naturally occurring minerals that caused the water to have an undesirable appearance, taste, or smell.

  • The third consultation recommended further characterization of the groundwater and surfacewater hydrology in the mining area to determine how the groundwater and surface water have interacted. ATSDR also recommended removal or other corrective action if mine tailings and sediments were found to contain elevated concentrations of metals in areas where human contact is likely.
  • NOTE: The settlement of the water quality litigation described previously requires the implementation of a comprehensive groundwater study, which should help address hydrology concerns. The data provided to ATSDR for review did not reveal mine or mill tailings or sediments with elevated levels of metals in areas where human contact was likely.

I. Petition

In September 1995, the Fort Belknap Community Council petitioned ATSDR to evaluate two large,open-pit, cyanide heap leaching, gold mines located adjacent to the south end of the reservation. Thecouncil believed that the mines pose a health hazard to the people of the reservation by releasingtoxic substances into the environment, especially into drinking water supplies.

J. Site Visit

ATSDR personnel conducted a visit to Fort Belknap and the surrounding area November 5-8, 1995,as part of the response to the September 1995 petition. Several groups from the community met with ATSDR personnel during the visit, including:

  • Phillips County commissioners and their guests
  • Fort Belknap Community Council
  • Health and environmental staff of the Community Council
  • Bureau of Indian Affairs, Fort Belknap Agency
  • Environmental staff of Zortman Mining Inc.
  • Bureau of Land Management, Lewistown office

ATSDR met with representatives of the groups listed above to gather all available environmentaldata pertaining to the issues under investigation, as well as to initiate contact with the various partsof the site community. In addition to information gathering, the ATSDR site team visited several of the areas about which concerns had been expressed.

K. Public Availability Sessions

Concerns were raised by community residents during public availability sessions with ATSDRrepresentatives held in March 1996. Concerns about the quality of the drinking water and pollution of surface water, sediments, and air, as well as numerous concerns about health, were expressed.

L. Demographics

According to the 1990 Census of Population and Housing (U.S. Bureau of Census, 1992), thedemographic statistics for within 1 mile of the site indicate that 55 persons reside in 48 households.Of the 55 persons, 42 are white; none are black; 7 are American Indian, Eskimo, Aleut; none areAsian or Pacific Islander; 1 is of Hispanic origin and none are members of other ethnic groups. There are 7 children aged six or younger, 12 females aged 15-44 and two adults aged 65 and older. Please refer to the demographics maps located in Appendix A.

M. Statement of issues

A number of environmental and health concerns related to perceived contamination from the mineand other issues have existed in and around the Fort Belknap community for several years. Many ofthese concerns have revolved around differences in data collected by various interested groups.Many other concerns have revolved around the aesthetic qualities of drinking water on thereservation. This document was prepared using all the environmental data that ATSDR wasprovided by the many different agencies, organizations, and individuals (see previous section, SiteVisit) the agency met with.

Because these data were collected for wide variety of uses, the sampling points, detection levels,analysis methods, and quality assurance and quality control procedures all varied considerably. Thisvariability resulted in numerous uncertainties about the accuracy and precision of the data fornumerical and statistical analysis, as well as uncertainties related to detailed comparison betweendata sets. Therefore, this discussion makes only qualitative comparisons. (See Appendices C and Dfor more information about the data used in this report.) If detailed quantitative data comparisons are desired, new data using standardized collection and analytical methods, health based detection levels, etc. will have to be collected.


A. Environmental Data and Exposure Pathways

Data from each of the drainages flowing in the direction of Fort Belknap (King Creek/Little PeoplesCreek from the Landusky Mine and Glory Hole/Lodge Pole, Beaver, and Big and Little WarmCreeks from the Zortman Mine) were reviewed to determine what contaminants were present atconcentrations above the ATSDR comparison values (i.e., which specific contaminants or groups ofcontaminants were found at elevated levels). See Appendix A for a map of surface water drainages.

For a definition of comparison values and how ATSDR uses them, see Appendix E; a briefdefinition and explanation is also provided in the Toxicological Evaluation section. Briefly, twotypes of comparison values are used in this document: (1) risk-based or human health-basedvalues, concentrations of environmental contamination known to be safe (that is, items in the tableslisted as AL, EPA SLG, MCL, pMCL, RBC, child RMEG, WHO), and (2) secondary standards,concentrations of environmental contamination known to cause unpleasant, but not dangerous,characteristics in water (that is, those listed in the tables as USGS, sMCL). Each of these acronyms isexplained in the tables and further described in Appendix E.

Once a determination has been made about which contaminants are present at concentrations greaterthan the comparison values, the data are evaluated to determine whether the contamination is likelyto move in the environment (e.g., from stream sediment to stream water, or from soil to air) and ifpeople are likely to be exposed to the contamination.

Exposure pathways can be completed or potential. A completed pathway indicates that humanexposure to contaminants has occurred in the past, is occurring, or will occur in the future. Apotential pathway indicates that exposure could have occurred in the past, is occurring, or will occurin the future. An exposure pathway can be eliminated from consideration if exposure has neveroccurred and never will occur. If there is uncertainty about whether the contaminants of concern inan exposure pathway are site related, the pathway will be evaluated as if they were.

The data provided to ATSDR for this document indicate that the only completed pathway isdrinking some of the water used for residential purposes at Fort Belknap (see the ToxicologicalEvaluation in the Health Concerns section for more information). Several other pathways arepotentially completed, including accidentally drinking contaminated surface water present in theLittle Peoples Creek drainage, Lodge Pole drainage, and other streams that may receive runoff fromeither of the mines; swimming or wading in the same contaminated surface waters; accidentallyeating tailings materials located in Mission Canyon because hands were not washed before puttingthem in a mouth or as a result of pica behavior; and breathing air contaminated with cyanide andother contaminants blown from the mining operations (see the Air Quality discussion included in theEnvironmental Concerns section for more information).

TABLE 1. Table 1 presents a summary of surface water data from selected sampling locations in theLittle Peoples Creek Drainage (King Creek, Swift Gulch, South Big Horn Creek, and Little PeoplesCreek), which receives surface water flow from the Landusky mine. The levels of sulfate, nitrate,and manganese in those surface waters exceeded human health-based comparison values. Leadanalyses were conducted using a detection level that was higher than the ATSDR comparison level.Consequently, ATSDR assumed the concentration exceeded the comparison value for purposes ofthis evaluation as a true concentration for lead could not be determined.

TABLE 2. Table 2 presents a summary of the data from selected sampling locations in the drainagesreceiving surface water runoff from the Zortman mine: Lodge Pole Creek drainage (Glory HoleCreek, Lodge Pole Creek), Beaver Creek, Little Warm Creek and Big Warm Creek. The levels ofsulfate, antimony(1), beryllium(2), manganese, and sodium in those sampling locations exceeded humanhealth-based comparison values.

TABLE 3. Table 3 compares domestic well data collected at the Fort Belknap Reservation with datacollected from wells in areas with known acid rock drainage problems. The levels of sulfate, iron,lead(3), nitrate, and sodium in the well water exceeded human health-based comparison values.

TABLE 4. Table 4 presents analytical data from three environmental media: groundwater collectedfrom domestic or public supply wells, groundwater collected from springs or monitoring wells, andsurface water collected from various surface water stations. Each of these media are subdivided intodrainages: Fort Belknap (which includes all groundwater or surface water collected within thereservation boundary); Landusky (which includes all groundwater or surface water collected fromany drainage of the Landusky Mine that is not within the reservation boundary); and Zortman(which includes all groundwater or surface water collected from any drainage of the Zortman Minethat is not within the reservation boundary).

The data in Table 4 are presented as ranges for each medium and drainage. Any maximum valuethat was detected from a Landusky or Zortman drainage that was flowing in the direction of FortBelknap, but was not within the reservation boundary, has been indicated with an asterisk (*). Allother maximum values expressed in Table 4 are from drainages flowing away from the reservation.

TABLE 5. Table 5 presents analytical data from rock, tailings, and sediment samples. Rock sampleswere collected from various locations at both the Zortman and Landusky mines. Tailings samplesincluded in the '78-'79 and '93 data sets were collected from the King Creek/Little Peoples Creekdrainage. Tailings/sediments were collected from the King Creek/Little Peoples Creek, Big Warm Creek, and Beaver Creek drainages.

The data presented in these tables are the basis for the discussion presented in the next section.

Table 1.

Surface Water Results from Selected Locations in the King Creek/little Peoples Creek Drainage, North of the Landusky Mine (Based on surface water data from ZMI and the Fort Belknap Reservation)
Contaminants (ppm) Comparison Values (ppm) L5 (King Creek headwaters) L6 (King Creek just inside res boundary) L19 (Swift Gulch) FB15 (Near KC headwaters at old beaver ponds) FB15b (250 ft. below old beaver ponds) FB12 (South Big Horn Creek) FB10 (North Fork LPC)
Sampling Dates   1979 - 1994 1979 - 1994 1985 - 1995 8/94 - 7/95 8/95 - 11/95 7/95 - 3/96 8/94 - 3/96
Specific Conductivity (µmhos/cm) 500µmhos/cm (USGS) 340 - 2010 293 - 838 48 - 593 535 - 762 707 313 358 - 427
Total Dissolved Solids (TDS) 500 (sMCL) 351 - 1930 293 - 838 53 - 419 394 - 450 447 - 483 216 - 335 252 - 300
Sulfate (SO4)
250 (sMCL)
500 (pMCL)
98 - 1070 69 - 260 12 - 210 17 - 123 116 - 123 72 - 124 12 - 24
Nitrate + Nitrite as N 10 (MCL) 7.3 - 36.9 ND - 1.29 ND - 1.49 <0.05 <0.05 <0.05 <0.05 - 0.08
Iron 0.3 (sMCL)
11 (RBC)
(trc)ND - 1.47 (trc)0.01 - 1.47 (trc)ND - 2.11 0.16 - 2.07 0.94 <0.05 <0.05 - 0.14
Lead 0.015 (AL) (trc)ND - 0.05 (trc)ND - 0.02 (trc)ND -0.02 <0.05 <0.05 <0.05 <0.05
Manganese 0.05 (sMCL, child RMEG)
0.84 (RBC)
(trc)ND - 0.15 (trc)ND - 1.19 (trc)ND - 0.08 0.11 - 0.4 0.29 <0.02 <0.02


NA Not Analyzed
ND Not Detected
(trc) Total Recoverable
See Appendix E for definitions and sources of the comparison values used in this table.

Table 2.

Surface Water Results in The Gloryhole, Lodgepole, Beaver, Little Warm, And Big Warm Creek Drainages, North of The Zortman Mine (Based on surface water data from ZMI and Fort Belknap)
Contaminants (ppm) Comparison Values
Z-5 (Gloryhole Ck near mine boundary) Z-7 (Lodgepole Ck near reservation boundary) Z-31 (Beaver Creek @ 1st tributary confluence from headwaters) Z-39 (Beaver Creek @ 2nd confluence from headwaters) Lodgepole Creek (S. side of Rt 11) Big Warm (above pond) Beaver Creek (W. of Rt 15) Little Warm (1 mi. E. of Rt. 15)
Sampling dates   5/81 - 10/93 1990 - 1995 1990 - 1995 1994 - 1995 8/94 - 4/96 8/94- 12/95 4/95 - 4/96 8/94 - 10/95
pH (S.U.) 6.5 - 8.5 (S.U.) 7.1 - 8.2 7.4 - 8.5 7.1 - 8.0 7.9 7.9 - 8.5 7.5 - 7.8 7.9 - 8.3 7.5 - 8.0
Specific Conductivity
500 µmhos/cm (USGS) 165 - 486 201 - 433 135 - 252 168 - 310 482 - 611 1880 - 2170 497 - 532 <7 - 2220
Total Dissolved Solids (TDS) 500 (sMCL) 105 - 292 83 - 267 65 - 158 127 - 243 287 - 364 1450 - 1870 288 - 326 1430 - 2000
Sulfate (SO4) 250 (sMCL)
500 (pMCL)
0.15 - 65 12 - 36 5.0 - 16 6 - 20 25 - 34 169 - 1120 13 - 38 778 - 1160
Antimony 0.006 (MCL) NA NA NA NA <0.05 <0.05 <0.05 - 0.06 <0.05
Beryllium 0.004 (MCL) NA NA NA NA <0.005 - 0.006 <0.005 - 0.007 <0.005 <0.005
Chromium 0.05 (MCL) <0.010 - <0.020 NA NA NA <0.02 <0.02 <0.02 <0.02 - 0.02
Iron 0.3 (sMCL)
11 (RBC)
0.06 - 2.84 (trc)ND - 0.68 (trc)ND - 0.32 (trc)ND - 0.5 0.24 - 0.48 <0.05 - 0.15 .36 - .54 <0.05 - 0.12
Manganese 0.05 (sMCL, child RMEG)
0.84 (RBC)
<0.10 - 21 (trc)ND (trc)ND (trc)ND 0.06 - 0.13 <0.02 0.4 - 0.6 <0.02
Sodium 20 (USGSb) - 200 (WHO) 1.0 - 7.0 3 - 7 2 - 4 3 - 4 <1 - 6 64 - 79 <1 - 19 55 - 70

NA Not Analyzed
ND Not Detected
(trc) Total Recoverable
See Appendix E for definitions and sources of the comparison values used in this table.

Table 3.

Fort Belknap Domestic Well Data And Groundwater Data From Known Areas With Acid Rock Drainage (ARD)(Based on data from the EIS and Fort Belknap)
Contaminants (ppm) Comparison Values '78 Domestic Well Data '90 - 95 Domestic Well Data ZL-142 (Ruby Gulch-bedrock) ZL-143 (Ruby Gulch-alluvium) ZL-119 (Montana Gulch-bedrock) ZL-113 (Montana Gulch-alluvium) ZL-125 (Montana Gulch-alluvium)
pH (S.U.) 6.5 - 8.5 S.U. 7.0 - 8.8 6.9 - 8.9 6.5 - 7.6 7.5 - 7.9 7 - 8 6.5 - 7.9 7.0 - 9.5
Specific Conductivity (µmhos/cm) 500 µmhos/cm
310 - 6100 379 - 6770 982 - 1990 1120 - 1300 488 - 940 541 - 2450 602 - 1250
Total Dissolved Solids (TDS) 500 (sMCL) 160 - 4100 325 - 5540 829 - 1800 954 - 1150 293 - 577 497 - 2250 390 - 986
Sulfate (SO4) 250 (sMCL)
500 (pMCL)
3 - 2550 10 - 3110 377 - 1070 569 - 658 91 - 190 27 - 1180 131 - 562
Arsenic 0.05 (MCL) <0.002 - 0.006 <0.001 - 0.0314 ND ND ND ND ND
Iron 0.3 (sMCL)
11 (RBC)
<0.01 - 11.5 <0.01 - 7.07 ND 0.07 - 0.07 ND ND - 0.11 0.14
Lead 0.015 (AL) <0.01 - <0.13 <0.001 - 0.0179 ND ND ND ND - 0.03 ND -0.01
Nitrate 10 (MCL) <0.1 - 31 <0.05 - 0.72 0.81 - 3.77 0.92 - 0.92 3.35 - 5.67 0.27 - 6.23 0.87 - 2.90
Sodium 20 (USGSb) - 200 (WHO) 1 - 1250 1.3 - 1480 6 - 12 7 - 9 2 - 178 2 - 8 15 - 27

ND Not Detected
See Appendix E for definitions and sources of the comparison values used in this table.

Table 4.

Summary of Surface Water And Groundwater Data in the Fort Belknap/Zortman Mining Inc. Area From a Variety of Sources1-9 (on next page)
  Domestic Wells Springs and Monitoring Wells  
Contaminants (mg/L) Comparison Values (ppm) Ft. Belknap1 Landusky2 Zortman3 Ft. Belknap4 Landusky5 Zortman6 Ft. Belknap7 Landusky8 Zortman9
pH (S.U.) 6.5 - 8.5 S.U. 6.9 - 8.9 5.92 - 8.24 6.26 - 7.89 7.1 - 8.1 3.3 - 11.8 2.60 - 8.7 6.9 - 8.6 2.7 - 8.6 2.5 - 8.5*
Specific Conductivity (µmhos/cm) 500 µmhos/cm (USGS) 379 - 6770 382 - 3390 373 - 438 167 - 1760 190 - 3390 141 - 9990 <7 - 2220** 48 - 10,700 53 - 4990
Total Dissolved Solids 500 (sMCL) 325 - 5540 193 - 1100 163 - 272 133 - 1480 140 - 3350 106 - 20200 225 - 2000** 48 - 14,700 15 - 6940
Sulfate 250 (sMCL)
500 (pMCL)
10 - 3110 37 - 608* 31 - 46 32 - 843 27 - 2360 11 - 6290 <5 - 1160 14 - 9960 3* - 3330
Antimony 0.006 (MCL) <0.05 <0.05 <0.05 - 0.06
Arsenic 0.05 (MCL) <0.005 - 0.0314 <0.005 - 0.158 <0.005 <0.001- 0.001 ND - 0.50 ND - 1.2 <0.001 - 0.04 ND - 5.51 ND - 0.24
Beryllium 0.004 (MCL) <0.001 <0.001 <0.001 - 0.007
Cadmium 0.005 (MCL) <0.001 - 0.002 <0.001 <0.001- 0.002 <0.001 ND - 0.08 ND - 0.56 <0.001 - 0.005 ND - 0.6 ND - 0.35
Chromium 0.05 (MCL) <0.001 - 0.003 <0.001 <0.001 <0.001 <0.001 - 0.24 BQL - 0.03*
Copper 1 (MCL) <0.001 - 0.93 BDL - 0.002 BDL - 0.01 <0.001 ND - 0.30 ND - 43.5 <0.001 - 0.039 ND - 2.34 ND - 14.8
Cyanide 0.20 (MCL) <0.005 <0.005 <0.005 <0.005 ND - 125 ND - 0.24 <0.005 ND - 0.14 ND - 1.38
Iron 0.3 (sMCL)
11 (RBC)
<0.01 - 7.70 <0.03 - 5.99 <0.03 <0.003 - 0.06 ND - 13.3 ND - 346 <0.03 - 2.07 ND - 536 ND - 247
Lead 0.015 (AL) <0.001 - 0.0179 <0.01 - 0.03 <0.01 <0.001 - 0.01 ND - 0.06 ND - 0.10** <0.001 - 0.20 ND - 0.34* ND - 0.19
Manganese 0.05 (sMCL, child RMEG)
0.84 (RBC)
<0.005 - 1.36 <0.02 - 0.16 <0.02 <0.01 ND - 46.7 ND - 72.2 <0.01 - 0.4 ND - 110 ND - 27.6
Nitrate/Nitrite 10 (MCL) <0.05 - 0.72 <0.05 - 6.38 0.22 - 0.29 <0.05 - 0.069 ND - 19.3* ND - 4.4 <0.05 - 0.21 BQL - 36.9* ND - 23.4
Sodium 20 (USGSb) -
200 (WHO)
1.3 - 1480 5 - 84 4 - 5 1.1 - 7.6 2 - 178 3 - 764 <1 - 78 1 - 1650 1 - 286
Zinc 5 (sMCL)
3 (child RMEG)
<0.01 - 0.9 <0.01 - 0.05 <0.01 - 0.03 <0.003 - 0.007 ND - 9.21 ND - 18 <0.003 - 0.1 ND - 25.4 ND - 13.5

ND Not Detected
BDL Below the detection level.
* Sample was collected in a drainage flowing in the direction of the Fort Belknap Indian Reservation.
** Value reported in table is the maximum value reported excluding data collected before 1990 or from sampling points not expected to be affected by ZMI.
See Appendix E for definitions and sources of the comparison values used in this table.

  1. Indian Health Service Water Quality Data, 1990 - 1996. Fort Belknap Utilities/Solid Waste Department 94 - 96. B&L Industries 8/95 (2 wells). TEAM Domestic Well data 9/95 (2 wells). USGS sampling data 8/94. Site Inspection, Analytical Results Report, King Creek, September 22, 1993.

  2. Storet database report dated 95/06/06 for wells TP-1 to TP-4 and Hydrometrics Inc., and the Analyses Summary Report for wells TP-1 to TP-4, 04/24/95 (sampling dates 83 - 95).

  3. Storet database report dated 95/06/06 for the Zortman community well, Z-8A and Hydrometrics Inc., Analyses Summary Report for Zortman community well, Z-8A, 04/24/95 (sampling dates 82 - 95).

  4. USGS groundwater and surface water data, 8/94, TEAM Groundwater Analysis, 9/95.

  5. Final Environmental Impact Statement, Zortman and Landusky Mines, Reclamation Plan Modifications and Mine Life Extensions, March 1996.

  6. Final Environmental Impact Statement, Zortman and Landusky Mines, Reclamation Plan Modifications and Mine Life Extensions, March 1996.

  7. Fort Belknap Community Council, Water Quality Surface Water Analysis results, 1994-1996, Red Thunder Surface Water Analyses, August 31, 1992. Team Surface Water Samples, 9/95. USGS Groundwater and surface water data, 8/94. Site Inspection, Analytical Results Report, King Creek, September 22, 1993. Indian Health Service (IHS) Surface Water Sample Analysis, 7/93.

  8. Final Environmental Impact Statement, Zortman and Landusky Mines, Reclamation Plan Modifications and Mine Life Extensions, March 1996. USGS Surface Water Data, Water Year, October 1989 - September 1990 and MDSL Surface Water Data, Little Peoples Creek near Hays, MT, sampled 6/91, from the Preliminary Assessment, King Creek, January 26, 1993. Site Inspection, Analytical Results Report, King Creek, September 22, 1993.

  9. Final Environmental Impact Statement, Zortman and Landusky Mines, Reclamation Plan Modifications and Mine Life Extensions, March 1996.

Table 5.

Summary of Hard Rock, Tailings, and Sediment Data in the Fort Belknap/ZMI Area From a Variety of Sources 1-4
  '78 - '79 Tailings Data2 '93 Tailings Data3 '87 - '93
Sediment/Tailings Data4
Contaminant (ppm) Comparison Values (ppm) Hard Rock1 Water-Soluble Metals Liquid Solid Above Cumberland Dam Below Cumberland Dam
Antimony 20 (child RMEG) 8 - 53       5.5 UJ - 9.0 UJ 6.3 UJ - 8.8 UJ  
Arsenic 20 (child RMEG) 10 - 443 0.01 - 0.18 <0.002 - 29 <0.01 - 40 74.4 - 112 71.7 - 80.2 7.5 - 1,1610.0 (sic)
Beryllium 300 (child RMEG) 2.9 - 18.7       0.58 - 1.1 0.51 - 0.67 <0.28 - 0.48
Cadmium 50 (child EMEG) <1 - 5           0.1 - 6.52
Chromium 300-50,000 (child RMEG) 60 - 1503       7.5 J - 18.6 J 8.8 J - 13.5 J <0.5 - 33
Copper 3100 (RBC) 5 - 505       24.3 - 49 20.6 - 29.8 0.99 - 13.8
Cyanide 1000 (child RMEG)   < 0.01 (BDL) <0.002 - 0.16 0.01 - 0.16      
Iron 23,000 (RBC) 4,100 - 63,340       7650 - 12800 7720 - 11200 5990 - 14800
Lead 400 ( EPA SLG) < 2 - 182 < 0.02 - 0.15 <0.01 - 60.1 1.2 - 94 175 J - 400 J 213 J - 236 J 3.5 - 2300
Manganese 7000 (Child RMEG) 10 - 824       305 J - 778 J 353 J - 390 J  
Selenium 50 (Child RMEG)             ND - 8
Sodium 20 - 200 (WHO) 0.15 - 3.32       44.5 - 72.4 65.6 - 70.6 59.7 - 104
Zinc 20,000 (Child RMEG) 11 - 185     0.23 - 71.9 123 J - 227 J 117 J - 156 J 12.3 - 194

U The element was not detected at or above the reported detection limit.
J The associated numerical value is an estimated quantity because the quality control criteria were not met.
BDL Below the detection level.
ND Not detected.
See Appendix E for definitions and sources of the comparison values used in this table.

  1. Bondar-Clegg (BC), 1989. ZMI Hard Rock data.
  2. Morrison-Maierie, 1979. Mill Tailings Investigations, Little Peoples Creek Drainage, Fort Belknap Indian Reservation, Montana. Prepared for U.S. Department of Interior, Bureau of Indian Affairs, Billings Area Office; EERC data in the Fort Belknap Community Council (Fort Belknap),Water Quality Plan 208 Project.
  3. Morrison Knudsen, 1993b. Site Inspection Analytical Results Report, King Creek.
  4. CERT Data in: Morrison Knudsen, 1993a. Preliminary Assessment, King Creek; Morrison Knudsen, 1993b. Site Inspection Analytical Results Report, King Creek; Red Thunder, 1992.

B. Environmental Concerns

The summary below addresses environmental concerns expressed to ATSDR staff. Whenappropriate, the chemicals discovered to be elevated above either type of comparison value arediscussed. See the Toxicological Evaluation section for more information about health effectsassociated with exposure to the chemicals.

Water Quality

The primary concern expressed by many community members pertained to the pollution of surface water and groundwater on the reservation.

Data collected by the United States Geological Survey, the United States Bureau of IndianAffairs, and the Montana College of Mineral Science and Technology revealed the sedimentaryaquifers in and around the Fort Belknap Indian Reservation to have always had variable waterquality. The Groundwater Information Center (GIC) of the Montana Bureau of Mines andGeology has indicated that water supply wells throughout Blaine, Phillips, and Valley countiescompleted in the Judith River and Eagle Formations have iron, manganese, TDS, and sulfateconcentrations exceeding federal secondary drinking water standards (ZMI, 1997). Datacollected in the southwest portion of the Fort Belknap Indian Reservation going back to 1936indicate the same elevations of these parameters (Feltis 1983).

Surface water flowing north from the Landusky mine through King Creek contained elevatedlevels of specific conductivity, total dissolved solids (TDS), sulfate, nitrate, iron, lead (lead wasassumed to be above the comparison value because the analyses were conducted with a detectionlevel greater than the comparison value and, therefore, a true concentration could not bedetermined) and manganese (Table 1). Concentrations decreased as the water flowed down thedrainage toward the reservation. By the time the water reached the confluence with South BigHorn Creek, there were no metals or other water quality indicators present at levels that couldpose problems either aesthetically or from a human health perspective. ATSDR is unable to saywhether lead was elevated in the monitored drainages because the apparent detection limit of0.05 parts per million (ppm) was well above the comparison value of 0.015 ppm.

Surface water originating near the Zortman Mine in Glory Hole and Lodgepole Creekscontained iron and manganese at levels exceeding the comparison values (Table 2). Samplestaken from Lodgepole Creek on the reservation indicated levels of specific conductivity, iron,and manganese that exceeded the comparison values. Big and Little Warm Creeks, which alsoflow north from the Zortman mine, contained sulfates, specific conductivity, and TDS (Table 2)at concentrations above ATSDR comparison values. Results from samples taken along BeaverCreek indicated the presence of specific conductivity, iron, and manganese above comparisonvalues. ATSDR is unable to say whether antimony was elevated in the monitored drainagesbecause sites were either not analyzed or the apparent detection limit of 0.05 ppm was wellabove ATSDR's comparison values for this metal, which is 0.006 ppm.

All other values for surface water (Tables 1 and 2) showed wide variation, but were generallywithin health-based comparison values. There does not appear to be any pattern or trend to thisdata. However, sampling additional points between the mines and the reservation samplingpoints might provide data that would clarify these results.

Table 3 presents domestic well data collected at the Fort Belknap Reservation in 1978 (pre-ZMI) and in the current time period (1990 - 1995). It also shows groundwater results frommonitoring wells screened in bedrock and alluvial aquifers in the Ruby and Montana gulches.The maximum levels of specific conductivity, TDS, sulfate, lead, nitrate, and sodium measuredin domestic wells exceeded comparison values and, with the exception of nitrate, were 5-8 timeshigher than the corresponding values in groundwater at the Montana and Ruby gulches, which are the drainages most affected by the mines.

Maximum concentrations from the 1990 - 1995 domestic well data for specific conductivity,TDS, and sulfate were 10-35% higher than the values from 1978; however all minimumconcentrations were below comparison values. None of the increases appear to be out of theordinary, especially in view of the fact that, historically, the concentrations have always beenhigh. The maximum levels of lead and nitrate in domestic wells significantly exceeded health-based comparison values in 1978, but were near or within comparison values in 1990-1995.The other substances in the domestic well samples appear to be isolated detections and represent no apparent trend or pattern of groundwater contamination (Tables 3 and 4).

Several people were concerned about lead contamination of their wells.

The maximum level of lead found in the data review by ATSDR was 0.308 milligrams per liter(mg/L), which is about 20 times the comparison value of 0.015 mg/L. It is from a home in FortBelknap Agency, which is located some miles from the mining. This concentration was onlydetected in one well and was not duplicated in that well during a later sampling (Fort BelknapUtilities, 1994 - 1995). Only one other well contained elevated levels of lead at a concentrationof 0.0179 mg/L. (This sample was also sent to a second lab, which reported the leadconcentration as <0.005 mg/L). This well was located in Hays. A treatment system wasinstalled and the well was retested within several weeks. The lead concentration had beenreduced to 0.0029 mg/L, well below the comparison value of 0.015 mg/L. All other dataprovided indicated no levels of concern related to lead contamination.

Many people described their drinking water as being red or leaving red stains. Black stains werealso described.

In most of the columns in Table 4, iron is above the 0.3 mg/L secondary maximum contaminantlevel (sMCL). The EPA has determined sMCLs for substances that, at higher levels, can causeunpleasant characteristics in drinking water. These secondary MCLs are based solely onaesthetic considerations (taste, color, staining, etc.), and generally have no implications forhuman health. Red staining such as that described by the community is one of the unpleasantcharacteristics that high levels of iron can impart to drinking water. Others include turbidity andunpleasant taste (van der Leeden, Troise, and Todd, 1990). Iron can also leave deposits on foodand stain plumbing fixtures and laundry when there is more than 0.3 ppm in the water (van derLeeden, Troise, and Todd, 1990).

At concentrations in excess of its sMCL of 0.05 mg/L, manganese can produce black stains.Because the range of values for manganese in domestic wells at Fort Belknap (Table 4) rangesfrom less than 0.005 to 1.36 mg/L, black staining is also likely to be a major problem in some homes.

People also described steamy or cloudy-looking water when first poured from the tap, which cleared up after sitting for a while.

Water may come out of the tap looking steamy or cloudy if it has sediment (solids) suspended init or if a lot of air is put into the water as it leaves the tap (aerator). If the water is allowed to sitfor a while, the cloudiness should go away, either because the air re-dissolves or the sediment settles. If the problem is related to solids, treatment systems are available to remove them.

People described a white scale that formed in their water containers over time.

A number of substances can combine to produce scale. These substances include calcium,carbonate, bicarbonate, magnesium, nitrate, silica, and sulfate. Sodium in the water canaccelerate scale formation (van der Leeden, Troise, and Todd, 1990). Although scale does notpose a danger to the health of someone drinking the water, it can be very destructive if allowedto accumulate in pipes, water heaters, dishwashers, etc.

To prevent the most common scale problems (calcium and magnesium salts), salts are removedfrom the water using two primary methods: ion exchange and precipitation. Ion exchange watersofteners replace the ions, which are calcium and magnesium, causing the "hardness," withsodium. This approach can cause problems for people on low-sodium diets. Precipitation watersofteners do not put sodium in the water, but they are far more complex to maintain than the simple ion exchange systems (Corbitt, 1990).

Several people mentioned that their water tasted "bad."

Bad taste, like the staining discussed previously, is another unpleasant characteristic that certainsubstances can impart to drinking water when those substances are present at levels greater thantheir sMCLs. Iron, manganese, sulfate, nitrate, and TDS are a few of the substances that cancause water to taste bad (van der Leeden, Troise, and Todd, 1990). All of these substances werepresent above their individual sMCLs, thus accounting for the bad taste that residentsexperienced. It should be noted that bad taste alone, although unpleasant, does not indicate that the water is unsafe to drink.

Another concern about the drinking water on the reservation was biologic contamination (by bacteria or other microscopic organisms).

For several years, King Spring has been posted as a biologic hazard. The contamination is mostlikely a natural result of wildlife activity in the area. Other biologic contamination issues on thereservation are related to monitoring and chlorination problems with the Jenny Grey, Lodge PoleElementary School, and Hays/White Cow water systems in late 1995 (MAP, 1996). The FortBelknap Community Council has since replaced the water plant manager. EPA water qualitystaff indicated that the routine monitoring results have recently been improving.

Biologic contamination of drinking water can lead to very serious health problems, includingdiarrhea and vomiting. To prevent waterborne disease outbreaks, maintenance of the drinking water plant is very important.

People were concerned about the tailings in the King Creek drainage and how far the tailingshad been washed downstream over time.

The tailings in King Creek were the result of historic mining at the Little Ben and August mines,beginning in the early 1980s and existing until 1993. ZMI removed the tailings stored above theCumberland Dam; however, some tailings remain in the drainage below the Cumberland Damwhere, over the years, they have been washed. Table 5 presents a summary of all rock andtailings data available for ATSDR's review. These levels are not of concern, even though a fewof the comparison levels are exceeded.

These levels are not of concern because it is unlikely that a child would regularly eat significantamounts of soil from these contaminated drainages. All of the comparison values listed in Table5 are based on the assumption of chronic (long-term) exposure to a child who eats an average of200 milligrams (mg) of contaminated soil every day. Because of the limited access to thesetailings, these assumptions significantly overestimate both how much and how often soil from this area might be eaten by local children.

Several people were concerned about the use of Ruby Gulch tailings in construction of the Bear Gulch Road.

The Bear Gulch Road was not built using tailings material from the Ruby Gulch. A relativelysmall amount of the tailings were used for some maintenance activities during construction. Thetailings were chemically tested before use to determine if they would leach metals or otherharmful chemicals as they weathered. The results of the tests indicated that there would be noproblem using the tailings (ATSDR, 1996a). In addition, the areas where the tailings were usedhave since been encapsulated with additional gravel and paving materials, greatly reducing the potential for any exposure to them.


Concern was also expressed about loss of flow in several of the drainages from the south ontothe reservation.

The EIS discusses the diversion of surface water as a result of mining disturbances in Sections3.2.3.1 and Impacts from the Landusky mine include a significant impact (loss of 16%of the watershed) to King Creek resulting from of activities at the Gold Bug and Queen Rosepits. These activities produced a lesser impact to Swift Gulch, a tributary to South BighornCreek, which joins with King Creek to become Little Peoples Creek. Impacts from the Zortmanmine are limited to a 0.6% loss of flow to the Lodge Pole Creek, and Beaver Creek has not beenaffected by current ZMI activities and would not be affected by any proposed expansionactivities (DOI, 1996).


People are concerned about decreasing numbers of all types of fish and wildlife.

In the past, the tailings in the King Creek drainage adversely affected beaver and fishpopulations. Major rainstorms resulted in large quantities of tailings being washed downstreamover a short period of time, causing a catastrophic loss of habitat for beaver and other wildlife(USFWS, 1974; Morrison-Maierie, 1979). The removal of the majority of the tailings from thedrainage by ZMI has greatly reduced this problem.

An aquatic study of the southern portion of Fort Belknap was included in the recent consentdecree as a supplemental environmental project. This study may provide more currentinformation about the potential for impacts on wildlife as a result of the historic and currentmining operations (EPA, 1996).

People are concerned about damage to vegetation resulting from the overspray of the cyanidesolution used on the heaps.

There is no vegetation in the immediate vicinity of the heap leach piles. Once the cyanide hasentered the air, it becomes a gas (hydrogen cyanide). Hydrogen cyanide gas is not removed fromthe air by water in the form of rain or snow, nor as a result of touching a surface, such as trees,grasses, etc. As a result, cyanide may be transported over long distances. Eventually, thehydrogen cyanide reacts with particles found in the atmosphere to form water, carbon dioxide,and nitric oxide (ATSDR 1995b).

People were concerned about reports of damage to vegetation that resulted from landapplication of cyanide solution.

Vegetation was damaged in the mid-1980s during land application of cyanide solution. Thecyanide in the solution was destroyed, or neutralized, with calcium hypochlorite before landapplication (ATSDR, 1996b). The reaction between the two substances caused a gas to formthat was damaging to the vegetation. Calcium hypochlorite is no longer used to neutralize thecyanide solution; it has been replaced with hydrogen peroxide, which does not damagevegetation.


Residents of the reservation have expressed concerns about various aspects of air quality,including emission of lead or hydrogen cyanide from the site.

There is no evidence in the air data reviewed by ATSDR that people from the reservation oranyone else, other than employees at ZMI, could be exposed to any air contamination (includingparticulates, lead, or hydrogen cyanide) at levels of health concern. Because ZMI has anemployee health monitoring program, which includes cyanide safety training, respiratory fit-testing, and maintenance components, exposure of employees to air contamination at levels of health concern would not be expected.


A. Community Health Concerns

The medical conditions reviewed in this section were identified as concerns by members of thecommunities, who participated in the public health availability sessions held in Hays, Lodge Pole,Malta and Landusky. Many of the concerns expressed by the community were also expressed by theFort Belknap Community Council and the tribal environmental department in the initial discussionsheld with the Council.

Several individuals were concerned that one or more of the chemicals identified may beassociated with their medical conditions, including reproductive cancers, lymphoma, thyroid cancer and thyroid conditions, diabetes, and arthritis.

None of the identified chemicals of concern at this site are known or suspected causes of thediseases or disorders (e.g., cancer, arthritis, diabetes, hepatitis, or respiratory and reproductiveproblems) identified as community health concerns at this site. ATSDR representatives reviewedthe environmental data and the IHS reports to identify any possible links. None were identified.

The known or suspected risk factors for these diseases follow:

Cervical cancer - Known risk factors include early (before age 16) sexual intercourse, earlyfirst pregnancy, multiple sex partners, and venereal disease. Involvement of a sexuallytransmitted virus is suspected.

Uterine cancer - Major risk factors include estrogen exposure without a proper balance ofprogestins; estrogen-secreting tumors (for example, ovarian); advanced liver disease; menstrualcycles without ovulation; and obesity. Uterine cancer is the most common malignancy (cancer)of the female genital tract in the United States. Approximately 80% of cases occur aftermenopause; less than 5% are diagnosed before age 40.

Ovarian cancer - This cancer is more common in industrialized countries among childlesswomen who experience "incessant (continuous) ovulation." Less than 5% of ovarian cancers are hereditary. Unknown physical, chemical, or dietary products may be contributing factors.

Prostate cancer - The causes of this cancer are unknown. Risk for prostate cancer is lowest forsingle men; married, widowed, and divorced men (in that order) have a greater risk. High ratesare reported in loggers, chemists, farmers, textile workers, painters, rubber tire workers, andworkers exposed to cadmium. Also, there is limited evidence that suggests an associationbetween prostate cancer and herbicide spraying by agricultural and forestry workers. Risk ishighest in Sweden, intermediate in the United States and Europe, and lowest in Taiwan, Japan,and among the Jewish population.

Lymphoma (Non-Hodgkin's) - This disease is associated with viruses (such as humanimmunodeficiency virus [HIV] and Epstein-Barr virus) and immune deficiency states such asacquired immunodeficiency syndrome (AIDS), organ transplants, congenital immunodeficiencysyndromes, and autoimmune disorders that impair the body's ability to fight infections. Somestudies have shown an association with use of phenoxy herbicides, while others have not.

Thyroid cancer - This type of cancer is associated with radiation exposure after a long latencyperiod (5-50 years; average: 25 years); hereditary factors; and chronic thyroid-stimulatinghormone elevation. The risk of thyroid cancer increases with age; women are affected 50% moreoften than men.

Thyroid problems - Goiter may be caused by inadequate dietary intake of iodine, defects ofthyroid hormone production, or ingestion of goitrogens (such as turnips) that contain antithyroidsubstances. The causes of hyperthyroidism and hypothyroidism are not completely understood,but both are probably autoimmune diseases.

Arthritis - Some forms are associated with infection by nematodes (filariasis), bacteria(gonorrhea, rheumatic fever, Lyme disease, and pyrogenic and suppurative arthritis), and viruses(rubella, mumps, HIV [AIDS], and hepatitis B). The cause of many forms is unknown.Rheumatoid arthritis is probably an autoimmune disease.

Degenerative osteoarthritis - The cause is unknown. However, risk factors include congenitaljoint abnormalities; virtually any disease process that alters the normal structure and function ofthe hyaline cartilage (for example, rheumatoid arthritis and gout); and acute or chronic trauma(including fracture) to the hyaline cartilage (padding in the joint) or tissue surrounding it (forexample, by prolonged overuse of a joint, as in certain occupations such as foundry work, coalmining, and bus driving).

Diabetes - Insulin-dependent diabetes mellitus (IDDM) results from a genetically conditioned,immune-mediated, selective destruction of >90% of the insulin-secreting beta cells of thepancreas. Non-insulin-dependent diabetes mellitus (NIDDM) is commonly associated withobesity, but genetic factors appear to be major determinants of the insulin resistance that is required for the development of NIDDM.

Several questions were raised about rashes described as small pimples and "very itchy" andrashes that were burning, itchy, and caused dry skin. Concerns were expressed that the rashesmight be associated with exposure to surface waters.

Excessive swimming can lead to chronic dryness, burning, and itching of the skin. It is entirelypossible that frequent bathing in some of the area surface waters that have very high levels ofdissolved solids could produce dermal effects. However, it is not clear that these dermal effects,if they occurred, would correspond to the rashes described by the petitioners.

Itching may also accompany a primary skin disease or dry skin, and persistent scratching mayproduce redness, papules (bumps), and crusts along scratch lines. Bathing can aggravategeneralized itching, especially if the patient has dry skin. Many drugs, especially barbiturates,such as sleeping pills, seizure medicine, and salicylates, such as aspirin, can cause itching.Itching can also be caused by poison ivy and certain other plants.

Women of child-bearing age were concerned about the relationship between the chemicals at themine and the number of miscarriages and tubal pregnancies among reservation residents.

None of the chemicals at the mine are plausible causes of miscarriages or tubal pregnancies inwomen on the reservation.

Spontaneous abortions (miscarriages) are more common than they are generally perceived to be. About 20-30% of women bleed or have cramping sometime during the first 20 weeks ofpregnancy, which, in some cases, may represent occult spontaneous abortions, and 10-15% haveclinically recognizable spontaneous abortions. About 85% of spontaneous abortions occur in thefirst trimester and tend to be related to fetal causes such as chromosomal abnormalities anddevelopmental abnormalities. Those occurring in the second trimester are usually related tomaternal factors such as congenital or acquired abnormalities of the cervix or uterus;hypothyroidism; diabetes mellitus; chronic nephritis; acute infection; use of cocaine, especiallycrack; and severe emotional shock.

Generally, tubal pregnancies represent less than 1% of all diagnosed pregnancies, and about halfof those are caused by a previous tubal infection. The chances of a tubal pregnancy increase withprevious tubal disease, ectopic pregnancy (10-25%), exposure to diethylstilbestrol, or inducedabortion. The incidence of tubal pregnancy is higher, and is rising, in minority populations.

Residents asked if excessive tiredness or fatigue could be associated with any of the chemicalsidentified as used by the mine.

The contaminants identified are not likely to cause excessive tiredness or fatigue. However,excessive tiredness and fatigue can be caused by the chronic anxiety that may be associated, inthis case, with fear of potential exposures to chemical contaminants, the possibility of the mineclosure and continuing layoffs, long working hours, and driving long distances.

A resident asked about the risks of being infected with hepatitis B.

The incidence of hepatitis is elevated in some areas of the Indian population. However, from theagency's review of health data collected at the Fort Belknap reservation, the risk of beinginfected with hepatitis B is about the same as that for any citizen in the state of Montana. InNorth America, the prevalence of hepatitis B carriers is less than one half of one percent, but thataverage will be higher or lower for specific subpopulations. The disease is caused by a virus(hepatitis B virus) that may be transmitted by sexual contact, transfusions, and hypodermicneedles shared by drug users. It may also be passed from mother to infant. Less common causes include viruses such as infectious mononucleosis and leptospirosis.

A concern was expressed during the public health assessment process about many"unconditional statements" regarding health risks to the tribes that are based on unreliable information or incomplete analysis.

The responses provided to the questions from community members about specific diseases arebased on current toxicologic and environmental information related to the particular disease.The health analysis considered the site-related information to determine if there are plausibleenvironmental causes for specific health conditions, or plausible association with the site-relatedchemicals. Health outcome data were collected from Indian Health Service to identify diseasecategories provided by IHS. Discussions were held with the state department of health to verifythe prevalence of the diseases of concerns in Hill, Blaine, and Phillips counties. In reviewing thesettlement of the water quality lawsuit as related to health issues, ATSDR supports thecommunity health evaluation that will be provided as a supplemental environmental program (SEP) so that the incomplete data can be addressed.

B. Health Outcome Data

A review of the morbidity (diseases) and mortality (deaths) data for the reservation indicated that theoverall rates of diseases and deaths were similar to rates in the Billings, Montana, area and otherIHS areas. The rates of hepatitis, AIDS, and tuberculosis on the reservation are also similar to rateselsewhere in the state of Montana (IHS, 1995; Engman, 1996)

ATSDR staff conducted a review of the available morbidity and mortality health data for thereservation to identify any possible links related to chemical exposures. The data sources includedFort Belknap Hospital, Inpatient Report for 1992 - 1995 (hospital discharges; days; and averagelength of stay by admission diagnosis recode and age groups); Fort Belknap Hospital, ContractHealth Service Report for 1990 - 1993 (hospital discharges; days; and average length of stay byadmission diagnosis recode and age groups); Fort Belknap Service Unit, Cause of Death By Countyof Residence for calendar year 1980 (IHS, 1996); and the Public Health Nursing Health Assessmentof the Fort Belknap Reservation for calendar year 1981 (IHS, 1981). Also, the Division ofEpidemiology within the state of Montana was contacted.

C. Toxicologic Evaluation

ATSDR's comparison values are screening values used to facilitate the initial selection of site-specific chemical substances, known as "contaminants of concern" (ATSDR 1992a). After thecontaminants of concern at a site have been identified, they are individually scrutinized in moredetail to determine whether, under site-specific conditions of exposure, they represent a realisticthreat to human health. Although concentrations at or below ATSDR's comparison values mayreasonably be considered safe, it does not automatically follow that any concentration above acomparison value will necessarily produce toxic effects. Comparison values are intentionallydesigned to be lower--much lower--than the levels that produced "no effects" in laboratoryanimals.

On the basis of the available water analyses and health outcome data, no adverse health effects areexpected to result from drinking Fort Belknap well water. Private wells at Fort Belknap yield "hard"drinking water that is high in dissolved solids and sulfate, as reflected in the high values for specificconductivity, TDS, and sulfate. The highest levels of sulfate and TDS detected in Fort Belknapdrinking water (private well #9) may be sufficient to cause a temporary cathartic effect (diarrhea) insome individuals, especially infants not accustomed to the local drinking water (National AcademyPress, 1980). However, residents are generally unaffected by the laxative properties of such waterbecause their systems have adapted to it.

The principal dissolved solids detected in drinking water, including iron, manganese, calcium,magnesium, and sodium, are all essential nutrients. Toxic effects related to dietary overload arerarely seen because blood levels of these essential elements are homeostatically controlled, that is,the rate at which they are absorbed increases when intake is low and decreases when intake is high(ATSDR 1992b). Although manganese levels exceeded comparison values in two private wells,ingestion of water from those wells is not expected to produce adverse health effects. Manganism, aneurologic disorder with symptoms similar to those of Parkinsonism, occurs in workers whochronically inhale large amounts of airborne manganese while working in mines, steel mills, andchemical industries (ATSDR, 1992b). However, manganism is not known to occur with oralexposure. No confirmed case of this disease has ever been reported to occur in humans after ingestion of manganese-contaminated drinking water.

Calcium and magnesium, which account for most of the hardness and alkalinity in drinking water,are not only relatively nontoxic, they are essential nutrients required in large amounts (severalhundred milligrams per day). Calcium even reduces the absorption of toxic metals such as lead andcadmium. The value used to separate soft from hard water was derived from practical considerationsof effects such as boiler scaling rather than from observations on human health. Soft water mayactually pose a greater threat to human health than does hard water. Some studies have shown acorrelation between soft water and higher rates of cardiovascular disease (National Academy Press,1980).

It is not possible to say whether antimony in groundwater exceeded drinking water standardsbecause the detection limit used (0.05 ppm) was higher than ATSDR's comparison value(MCL=0.006 ppm). It is possible to say only that, whatever the absolute levels, the maximumvalues were no more than eight times the MCL, if they exceeded the MCL at all. No data areavailable on the health effects, if any, of chronic oral exposure to such levels of antimony. Muchlarger, acutely toxic doses are highly irritating to the gastrointestinal tract and tend to inducevomiting, thereby limiting the occurrence of systemic effects (ATSDR 1992c). Most othertoxicologic data on antimony are from studies of occupational inhalation exposure and have little orno bearing on low-level exposure via drinking water.

Although lead was found to exceed drinking water standards in a few isolated samples, thesedetections were not reproducible. Most individual measurements during this decade were less than0.0005 ppm--well below the action level of 0.015 ppm. None of the confirmed levels of lead in wellwater represent any hazard to public health.

On the basis of monitoring data available to the agency, ATSDR has concluded that because of its"hardness" and high levels of TDS, the drinking water at Fort Belknap exceeds certain sMCLsbased solely on aesthetic considerations, but does not pose any public health hazard to adapted populations.


  1. Review of the data provided to ATSDR has shown no apparent public health hazard to theresidents of Fort Belknap. The data reviewed provides no evidence that people have been, or arebeing, exposed to environmental contamination in sediments, surface water or groundwaterlocated within the boundaries of the reservation at dangerous levels.

  2. As a result of the lack of local groundwater flow and groundwater and surface water interactioninformation, future exposure poses an indeterminate public health threat. The groundwater studyrequired by the Consent Decree, resulting from the lawsuit settlement, will supply additional information that may address this current lack of information.

  3. A few persons from the reservation have consumed water from private wells containing lead atlevels of health concern in the past; however, these levels have not been reproducible and do not pose a current threat.

  4. Private wells on the reservation also contain aesthetically unappealing levels of iron, manganese,sodium, sulfate, total dissolved solids, specific conductivity, and pH. On the basis of the datareviewed by ATSDR, it is not possible to conclusively determine whether these elevated levels are naturally occurring or are related to contamination from the mine.

  5. People involved in recreational activities in the area may be exposed to contamination in seepsand springs as well as in surface water drainages. However, these exposures are expected to be infrequent and would not result in adverse health effects in adults or children.

  6. There is no evidence that people from the reservation are exposed to any air contamination. ZMIemployees may be exposed to air contamination at levels of health concern, but because they arerequired to participate in a health and safety program designed to protect them from such exposures, it is unlikely that these exposures will lead to adverse health effects.

  7. ATSDR supports the community health evaluation that will be provided as a supplemental environmental program (SEP) to the settlement of the water quality lawsuit. The agency is available to provide assistance as needed.


  1. Any additional environmental data that is gathered should follow a standardized sampling planthat defines the sampling and analysis methods, locations, detection levels, and other elements tobe used for each kind of data collected. A quality assurance plan should be developed to ensurethat data are representative of the site conditions and are accurate, precise, and reproducible.

  2. If the data are to be used to determine whether the contaminated media might be of concern tohuman health, the analytical methods used should permit detection of substances at, or below, known health-based comparison values. ATSDR can provide assistance, as needed, in identifying those health-based comparison values.

  3. If requested, ATSDR will review any additional environmental or health outcome data provided to the Agency.


Agency for Toxic Substances and Disease Registry (ATSDR), 1992a. Public Health AssessmentGuidance Manual, U.S. Department of Health and Human Resources, Atlanta, GA 30333.

Agency for Toxic Substances and Disease Registry (ATSDR), 1992b. Toxicological Profile forManganese. Department of Health and Human Services, Atlanta, Georgia 30333.

Agency for Toxic Substances and Disease Registry (ATSDR), 1992c. Toxicological Profile forAntimony. Department of Health and Human Services, Atlanta, Georgia 30333.

Agency for Toxic Substances and Disease Registry (ATSDR), 1995a. ATSDR Record of Activity,documenting discussions during ATSDR site visit to the Fort Belknap/ZMI area, dated 11/05/95.

Agency for Toxic Substances and Disease Registry (ATSDR), 1995b. Draft Toxicological Profilefor Cyanide. Department of Health and Human Services, Atlanta, Georgia 30333.

Agency for Toxic Substances and Disease Registry (ATSDR), 1996a. ATSDR Record of Activity,documenting a discussion with Mr. Cordell Ringel, BIA Billings Office on October 3, 1996.

Agency for Toxic Substances and Disease Registry (ATSDR), 1996b. ATSDR Record of Activity,documenting a discussion with Scott Haight, BLM, on September 16, 1996.

Agency for Toxic Substances and Disease Registry (ATSDR), 1996c. ATSDR Record of Activity,documenting a discussion with Jay Sinnott, EPA Montana Office on September 17, 1996.

B&L Industries, 8/95. Fort Belknap domestic well data: 2 wells.

Bondar-Clegg (BC), 1989. ZMI hard rock (ore) analysis.

Casiato, D.A., and Lowitz, B.B., 1995. Manual of Clinical Oncology, Third Edition, Little, Brownand Company, New York, NY.

The Citizens' Environmental Laboratory (Red Thunder's data), 8/92. Limited surface water andsediment data.

Corbitt, Robert A., 1990. Standard Handbook of Environmental Engineering, McGraw-Hill, Inc.,New York.

DOI, 1996. U.S. Department of the Interior, Bureau of Land Management (BLM) and State ofMontana, Department of Environmental Quality, Hard Rock Bureau, 1996. Final EnvironmentalImpact Statement, Zortman and Landusky Mines, Reclamation Plan Modifications and Mine LifeExtensions, Volumes I & II. Engman., Telephone discussion with Ms. Eng, Montana StateEpidemiologist regarding health conditions in Hill, Blaine and Phillips Counties, June, 1996.

Environmental Protection Agency (EPA), 1996. In the United States District Court for the Districtof Montana, Billings Division. United States of America, and the State of Montana versus PegasusGold Corporation and Zortman Mining, Inc., Civil Action No. 95-95-BLG-JDS and Gros VentreTribe, Assiniboine Tribe, Fort Belknap Community Council, and Island Mountain ProtectorsAssociation versus Pegasus Gold Inc., Pegasus Gold Corporation, and Zortman Mining Inc., CivilAction No. 95-96-BLG-JDS.

Feltis, 1983. Ground-Water Resources of the Fort Belknap Indian Reservation, North-CentralMontana. Montana Bureau of Mines and Geology Memoir 53.

Fort Belknap Community Council (Fort Belknap), undated. Water Quality Plan 208 Project.

Fort Belknap Community Council, 1994 - 1996. Water Quality Surface Water Analysis Results.

Fort Belknap Utilities, 1994 - 1995. Includes data for the Jenny Gray Well (3090042), the MissionSubdivision (3090043), Lodge Pole Housing (3090047), White Cow Canyon (3090044), MissionSchool (3090043), Lodge Pole Elementary (3090046), and Agency (3090041).

Grinell Agreement, 1896. Congressional Record, 54th Congress, 1st Session, Document No. 117. In the Senate of the United States, February 12, 1896, the Vice-President presented the followingletter from the secretary of the Interior, transmitting an agreement made and concluded October 9,1895, with the Indians of the Fort Belknap Reservation, in Montana, by William C. Pollock, GeorgeBird Grinnell, and Walter M. Clements, commissioners appointed under the provisions of the Act ofMarch 2, 1895.

Hydrometrics Inc., 4/95. Analyses Summary for wells TP-1 to TP-4 and the Zortman CommunityWell Z-8A).

Indian Claims Commission, Undated. THE BLACKFEET AND GROS VENTRE TRIBES OFINDIANS vs THE UNITED STATES OF AMERICA, Docket No. 279-C and The FORTBELKNAP INDIAN COMMUNITY vs THE UNITED STATES OF AMERICA, Docket No.250-A, Plaintiffs' Requested Findings of Fact and Brief, Volume III of V, Land, Mineral, Pollutionand Timber Findings.

Indian Health Service, 1990 - 1996. Domestic well data.

Indian Health Service, 1993. Surface water data: 4 samples.

Indian Health Service, 1995. Fort Belknap Hospital - Inpatient Report, Hospital Discharges, Days,and Average Length of Stay By Admission Diagnosis Recode and Age Groups (1992 - 1995), FortBelknap Hospital - Contract Health Service Report, Hospital Discharges, Days, and Average Lengthof Stay By Admission Diagnosis Recode and Age Groups (1990 - 1993), Fort Belknap ServiceUnit -Cause of Death By County of Residence (Calendar Year 1980).

Indian Health Service, 1981. Public Health Nursing Health Assessment of the Fort BelknapReservation

The Merck Manual of Diagnosis and Therapy, 1992. Sixteenth Edition (Robert Berkow, MD,Editor-in-Chief), Vol. I: General Medicine and Vol. II: Specialties, Merck & Co. Inc., Rahway, N.J.

Midwest Assistance Program (MAP), 1996. Fort Belknap Agency Water Treatment Plant Tripreport dated March 17, 1996, and attachments.

Morrison-Maierie, Inc., 1979. Mill Tailings Investigations, Little Peoples Creek Drainage, FortBelknap Indian Reservation, Montana. Prepared for U.S. Department of Interior, Bureau of IndianAffairs, Billings Area Office.

Morrison Knudsen, 1993a. Preliminary Assessment, King Creek.

Morrison Knudsen, 1993b. Site Inspection Analytical Results Report, King Creek.

National Academy Press, 1980. Drinking Water and Health, Vol. 3, Washington, D.C.

Pegasus Gold, 1993. Letter to Mr. Duncan Adams from John Fitzpatrick dated October 26, 1993.

Storet data base report 95/06/06 for wells TP-1 to TP-4 and Z-8A.

TEAM Data 9/95. Results of analysis of 6 samples: 2 streams, 2 domestic wells, 2 springs.

U.S. Bureau of Census, 1992 Tiger Files

U.S. Department of the Interior, Fish and Wildlife Service (USFWS), 1974. Memorandum fromLarry C. Peterson, Fishery Management Biologist, to James Canan, Area Director, Billings Bureauof Indian Affairs Area Office, November 18.

United States Geological Survey (USGS) Data 1/95. Analytical results from 9 surface watersamples (only used samples 1- 4 and 9, the others are too far north); 3 spring samples and 2 well(monitoring).

van der Leeden F., Troise, F.L., and Todd, D.K., 1990. The Water Encyclopedia, 2nd ed., LewisPublishers: Chelsea, MI.

ZMI, 1997. Summary of Natural Water Quality Conditions. Prepared for Zortman Mining, Inc. Based on U.S. Geological Survey and Montana Bureau of Mines and Geology ResearchDocuments. Found as Appendix A in Zortman Mining letter to Susan Muza, July 17, 1997.

Zortman-Landusky Water Resources Data Analysis Report, Draft Final, August 1995.

1. Antimony analyses were conducted using a detection level above the ATSDR comparison level; therefore, because the true value is not known, it is assumed to exceed the screening value.
2. Beryllium analyses were conducted using a detection level above the ATSDR comparison level; therefore, because the true value is not known, it is assumed to exceed the screening value.
3. Lead analyses were conducted using a detection level above the ATSDR comparison level; therefore, because the true value is not known, it is assumed to exceed the screening value.

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