PUBLIC HEALTH ASSESSMENT
ANNIE CREEK MINE TAILINGS
(RELIANCE TAILINGS)
LEADE, LAWRENCE COUNTY, SOUTH DAKOTA
ENVIRONMENTAL CONTAMINATION AND OTHER HAZARDS
This section of the public health assessment describes previous environmental sampling conducted at the Annie Creek Mine Tailings and identifies contaminants of concern found in specific site media.
ATSDR selects contaminants of concern based upon the following:
| (1) | concentrations of contaminants on- and off-site. |
| (2) | sampling locations and frequency, field data quality, laboratory data quality; |
| (3) | comparison of on-site and off-site concentrations with background concentrations, if available and with health assessment comparison values for noncarcinogenic and carcinogenic endpoints; and |
| (4) | community health concerns. |
It is emphasized that identification of a contaminant of concern in this section does not mean that exposure to the contaminant will cause adverse health effects. Instead, the selected contaminants are further evaluated in subsequent sections of the public health assessment.
The data tables provided in Appendix II include the following abbreviations and/or acronyms:
| CREG EMEG RMEG ppm ppb mg/kg ug/l |
= = = = = = = |
Cancer Risk Evaluation Guide Environmental Media Evaluation Guide Reference dose-based Media Evaluation Guide parts per million (mg/L water or mg/kg soil) parts per billion (ug/L water or ug/kg soil) milligram per kilogram microgram per liter |
Comparison values for ATSDR public health assessments are media-specific concentrations that are used to select environmental contaminants for further evaluation. These values include Cancer Risk Evaluation Guidelines (CREGs), Environmental Media Evaluation Guides (EMEGs), Reference dose-based Media Evaluation Guides (RMEGs),and other relevant guidelines.
A CREG is a media-specific screening value derived By ATSDR from EPA cancer slope factors. A CREG represents the estimated contaminant concentration based on one excess cancer in a million persons exposed to that contaminant over a lifetime. EMEGs are media-specific screening values derived by ATSDR from ATSDR minimal risk levels (MRLs), while RMEGs are derived from EPA reference doses (RfDs). ATSDR MRLs and EPA RfDs are estimates of daily exposure to a contaminant that are unlikely to cause adverse, non-carcinogenic health effects.
A. Environmental Contamination
Site contaminants were detected in sediments/surface soils, groundwater, surface water, and biota. Environmental investigations were conducted prior to 1990 for the Hazard Ranking System Document and prior to 1993 for the Engineering Evaluation and Cost Analysis for the Reliance Tailings Site. Data from both investigations were summarized in this public health assessment.
Sediments and Surface Soil
At one time, there were 2 sources of surface deposits: 1) the old Reliance Tailings (115,000 tons) and 2) the tailings deposited in the floodplain of Annie Creek (the result of the 1909 flood and erosion---approximately 5,920 tons). Since 1989, the Reliance Tailings have been encapsulated under 60-150 feet of waste rubble. The concentration of the contaminants in the tailings prior to installation of the waste rubble facility are displayed in Table 1 (Appendix II). Only arsenic concentrations in surface deposits exceeded environmental values.
During an aerial survey conducted in 1991 (8), tailings material was located within 300 feet of the confluence of Annie and Spearfish Creek. There was no visual evidence of tailings beyond this point. It was also observed during this investigation, that most of the tailings in the floodplain were covered by vegetation.
In order to determine the lateral and vertical extent of the dispersed Reliance Tailings, samples of streambed sediments and surface soils were collected in 1992 along Annie and Spearfish Creek (Table 2 Appendix II. sampling locations) and (Table 3, Appendix II. contaminant concentrations). Arsenic was the primary contaminant detected in the sediments. Arsenic concentrations in sediments reached a maximum concentration of 1272.0 mg/kg at the headwaters of Annie Creek and decreased in sediments at the lower reaches of Annie and Spearfish Creek. Antimony, barium, strontium, and zinc were reported above background concentrations but were at concentrations less than environmental media comparison values (Table 3, Appendix II).
Arsenic and strontium were detected above background concentrations in surface soil along Annie and Spearfish Creek (Table 4, Appendix II). Arsenic concentrations exceeded environmental media comparison values. Strontium concentrations did not exceed environmental comparison values.
Groundwater
Groundwater Sampling Data 1981-1991
A groundwater sample from the Wharf Resources water supply well, which is upgradient from the tailings, did not contain a measurable quantity of arsenic (<1.60 ug/L). Low levels of barium, iron, lead, manganese, and zinc were detected in the water supply well, but the concentrations of these contaminants did not exceed environmental comparison values.
A groundwater sample was taken from a well down gradient of the Reliance Tailings, completed in the alluvium along Annie Creek. The arsenic concentration of this groundwater was 15.1 ug/L. This groundwater sample was obtained from a well collared with tailings. It is thought that this is the source of the arsenic in the sample. This well is not used as a drinking water source.
Two off-site residential well samples had been obtained. At the residence nearest to the site, the Kannenberg well, the arsenic concentration was < 1 ug/L. At a residential well, 0.8 miles downstream of the confluence of Annie and Spearfish Creek, the arsenic concentration was 7 ug/L.
Groundwater Sampling Data 1992-1993
Between 1992-1993, 3 new alluvial groundwater monitoring wells were bored in Annie Creek in addition to the 2 existing wells. Groundwater quality was monitored between June-October 1992 and in January, March, and April 1993. Arsenic, nitrate, selenium, and zinc was detected in the groundwater samples. The range of total arsenic concentrations in 1992 was 2-80 ug/L. In 1993, the arsenic concentration range was 4-19 ug/L. The total nitrate concentrations in groundwater in 1992-93 were well below the MCL of 10,000 ug/l. Selenium (total) was not detected in the groundwater samples except for one hit of 5.8 ug/L. The total zinc concentrations ranged from 1.6-37.0 ug/L. The reported concentrations of total selenium or zinc did not exceed environmental comparison values.
Groundwater samples were analyzed for dissolved metals (Table 5, Appendix II). Dissolved arsenic concentrations in groundwater ranged from 2 ug/L to 23 ug/L in Annie and Spearfish Creek. All the dissolved arsenic concentrations were below the MCL of 50 ug/L. Only at one monitoring well (AC-4, a shallow well, 7.8 feet deep, which is collared in alluvium containing concentrations of 300-700 mg/kg arsenic) did total arsenic exceed the MCL (4 times). All total arsenic values were obtained from water samples with elevated total suspended solids. Excluding the total arsenic samples with high suspended solids, the water quality of the groundwater was below the MCL in all reaches of Annie Creek.
Dissolved antimony was detected in a range 7-7.4 ug/L which exceeds the MCL of 6 ug/L in the upper reaches of Annie Creek. Dissolved beryllium, cadmium, selenium, lead and nitrate were detected at AC1 and AC6 below the MCL. Dissolved manganese concentrations exceeded the environmental comparison values at AC1 and AC4.
Surface Water
Surface water samples have been obtained at 1) the headwaters of Annie Creek, 2) prior to the confluence of Annie Creek with Spearfish Creek, and 3) in Spearfish Creek. Additionally, surface water samples have also been obtained both pre- and post-construction of the waste rubble facility at the headwaters of Annie Creek (Table 6, Appendix II). In 1993, surface water quality from the headwaters of Annie Creek to locations in Spearfish Creek were monitored.
Surface Water Data Prior to 1992
Surface water samples were taken at five locations below the tailings (headwaters of Annie Creek), both pre- and post-construction of the waste rubble facility (Table 6, Appendix II). The arsenic concentration in surface water in Annie Creek ranged from 10.0 - 2,950.0 ug/L prior to installation of the waste rubble facility. Aluminum, manganese, vanadium, and zinc concentrations in the pre-construction surface water sample exceeded environmental comparison values. Data was not available for post-construction levels of aluminum, manganese, vanadium, and zinc in surface water. Post-construction of the waste rubble facility, the arsenic concentration in the surface water at the headwaters of Annie Creek decreased to a range of 27.0 - 460.0 ug/L (8).
Arsenic concentrations in surface water were measured in Annie Creek prior to it's confluence with Spearfish Creek. Before the construction of the waste rubble facility, the arsenic concentration in surface water ranged from 15 ug/L to 50 ug/L. Only one post-construction surface water sample was taken at this location, the value for arsenic contamination was 28 ug/L.
Surface water samples have been obtained both upstream and downstream of the confluence of Annie and Spearfish Creek by Wharf Resources and the United States Geological Survey (U.S.G.S.). In samples obtained by Wharf Resources, the arsenic concentration upstream in Spearfish Creek prior to its confluence with Annie Creek was < 1.6 ug/L. At the confluence of Annie and Spearfish Creek the arsenic concentrations ranged from 2 to 42 ug/L. Further downstream of the confluence of Annie and Spearfish Creek, arsenic concentrations ranged from <1 to 176 ug/L. DENR collected surface water samples along Spearfish Creek. From January 1987- Nov. 1990 the arsenic concentrations downstream of Annie Creek ranged from 5-26 ug/L.
In 1992, the surface water quality of Annie and Spearfish Creek was again monitored (Table 7, Appendix II). Arsenic, nitrate, nitrite, and selenium were detected. Arsenic concentrations in surface water decreased from concentrations as high as 81.6 ug/L in the upper reaches of Annie Creek to very low levels (2.3-5.2 ug/L) in Spearfish Creek. Arsenic concentrations in the surface water exceeded environmental comparison values. Nitrate concentrations were elevated in the upper reaches of Annie Creek (maximum reported concentration 8850 ug/L) and decreased in the lower reaches of Annie and Spearfish Creek to a concentration of 2180 ug/L. Nitrites were detected at 2 locations in Annie Creek at 11 and 22 ug/L. In Spearfish Creek, the nitrite concentration was 12.5 ug/L. Selenium concentrations were detected between 2.2-6.3 ug/L along Annie and Spearfish Creek. Nitrite, nitrate, and selenium concentrations in Annie and Spearfish Creek were detected at values below environmental comparison values.
Spearfish Municipal Water Supply
The City of Spearfish currently obtains its water supply from a 600 foot well located in the Madison Formation. In the past, municipal water was obtained from Spearfish Creek. There were three diversions of Spearfish Creek between the confluence with Annie Creek and the City of Spearfish. There were two hydroplants for Homestake Mining Company and the City of Spearfish Municipal water intake. Between the Hydroplant #1 and the City of Spearfish Municipal water intake, Spearfish Creek is dry. The only water that reached the city water supply was from springs and drainages below Hydroplant #1. Therefore, contaminated surface water from Annie and Spearfish Creek did not reach the Spearfish municipal intake. A letter from the City of Spearfish stated that no water from Annie Creek reached the Spearfish's municipal water intake.
Air
There were no data available to review regarding air quality near the waste rubble facility. Since the tailings are covered by 60-150 feet of waste rock, they are not susceptible to wind erosion and are unlikely to be dispersed by the wind. In order to determine if wind dispersion of the tailings below the Annie Creek drainage was a significant pathway of exposure: 1) meteorological data was reviewed (e.g. wind speed, duration of snow cover) 2) the extent of the vegetative cover was assessed 3) and the extent of public access to the Annie Creek drainage was determined.
The data reviewed indicated that the tailings were covered by snow or vegetation most of the year. The tailings particle size was determined to be large, which made it less susceptible to wind erosion. Recreational land use around the headwaters of Annie Creek was very limited (occasional fisherman or hiker).
Fish
Wharf Resources conducted fish tissue analyses in Annie Creek and Spearfish Creek in 1990 (Table 8, Appendix II). Brown trout were not found in Annie Creek. Elevated concentrations of arsenic were detected in bottom-feeding fish (mountain suckers) in Annie Creek. Less than 0.2 mg/kg arsenic was detected in brown trout in Spearfish Creek.
In 1992, fish samples were obtained from Annie and Spearfish Creek (Table 9, Appendix II). Whole fish and fillets were analyzed for arsenic, lead, and selenium content. Mountain suckers were the only fish collected in the upper reaches of Annie Creek. Brook and brown trout were collected in the lower reaches of Annie and Spearfish Creek.
Arsenic was detected in a range of 3.0 - 34.0 mg/kg in mountain suckers in Annie Creek. Lead was detected in only one sample at 0.8 mg/kg. Arsenic concentrations in whole brook trout ranged from 3.0-33.0 mg/kg and in brown trout ranged from 0.5- 18.0 mg/kg. Arsenic was not detected in brook trout fillets collected from Spearfish Creek. In whole brown trout arsenic concentrations ranged from 2.0-13.0 mg/kg. Lead was not detected in any of the trout samples. Selenium was detected in brook trout (fillet) (range 1.0-4.0 mg/kg) and in brown trout (whole) (range in Spearfish Creek.
B. Quality Assurance and Quality Control
The following quality assurance and quality control (QA/QC) procedures were used by the organizations that collected and analyzed the environmental monitoring samples evaluated in this public health assessment. This information is reviewed by ATSDR to determine whether the monitoring results were obtained based on standard sample collection procedures and laboratory analysis methods.
Samples obtained by EPA contractors were collected using pre-cleaned, prepackaged tools and were placed in clean plastic or glass containers provided by the laboratory. Tools were decontaminated according to EPA guidance. Field instruments were calibrated daily. No sample collection problems were noted. Duplicates and trip blanks were obtained by the contractor. Samples obtained by the EPA contractor were preserved according to EPA guidance and no sample preservation problems were noted. Chain of custody documents were maintained on each sample during shipment to the laboratory.
Lab instruments used by EPA contractors were calibrated according to National Bureau of Standards criteria. Laboratory analytical methods were consistent with EPA recommended procedures. The analytical results were flagged with appropriate QA/QC notation.
ATSDR evaluated physical hazards that may cause injuries or other adverse health effects that
are not specifically related to toxic substances. No unusual physical hazards were noted. Wharf
Resources currently operates a mine on the site. Warning signs have been posted around the
periphery of the site to warn visitors of routine mining hazards such as blasting.
ATSDR evaluated exposure pathways that might result from human exposure to contaminants in the environment associated with the site. ATSDR considers a human exposure pathway to consist of five components: a source of contamination, an environmental medium in which exposure may occur (air, water, etc.), a point of human exposure, a route of human exposure, and a receptor population.
ATSDR classifies exposure pathways in which all five components are present in the past or present, as a completed pathway. If a component is missing or exposure is possible but not likely to occur, the pathway may be classified as a potential pathway. Contaminants that exceeded ATSDR comparison values in completed and potential exposure pathways are evaluated in further detail in the Public Health Implications section of the public health assessment.
If exposure is not likely because several pathway components are not present, then the pathway is eliminated from further analysis in subsequent portions of the public health assessment. Exposure pathways are evaluated in the following sections.
There were no completed pathways indicated at this time.
B. Potential Exposure Pathways
Surface Deposits
Tailings from the headwaters of Annie Creek have been dispersed through past flooding and erosion. Even though the headwaters of Annie Creek are remote, there is the potential that an occasional vacationer may access the area and come in contact with the tailings in the sediments in the flood plains. An individual could be exposed to contaminants in the tailings either by incidental ingestion, inhalation, or dermal contact. Dermal contact with the tailing material is not considered to be a significant pathway of exposure since absorption of the tailing material through the skin is negligible.
Sediments/Surface Soils
The sediments/surface soils of Annie and Spearfish Creek are contaminated with tailings. Residents and vacationers that access areas around Annie and Spearfish Creek could be exposed to contaminants in the sediments/surface soil by incidental ingestion, inhalation, or dermal contact. Exposure to the contaminants in the sediments/surface soils via ingestion, inhalation, or dermal contact is expected to be infrequent since 1) the sediments are underwater for most of the year and 2) there is partial vegetative cover over the tailings on the banks of the creeks. Dermal contact with the sediments during activities such as wading is not expected to be a significant exposure pathway since absorption of metals through the skin is negligible.
Groundwater
Residents and vacationers at the homes and cabins along Annie and Spearfish Creek may use groundwater from wells screened in the alluvium/colluvium adjacent to Spearfish Creek. There are 20 residences in the area of the site. Fifteen of these homes are considered vacation homes (limited annual occupancy), 3 as permanent residences, and 2 as summer residences. One permanent residence is located on Spearfish Creek upstream from its confluence with Annie Creek. The 2 other permanent residences are about 1 mile downstream of the confluence of Spearfish and Annie Creek. The only home in the Annie Creek drainage is a vacation home. Thirteen of the residences have groundwater wells. Most of the wells are shallow (10-50 feet) and are probably completed in the alluvium. Only one residence uses surface water for household purposes (toilet, washing dishes but not drinking water).
Surface Water
Vacationers could be exposed to surface water contaminants through incidental ingestion or dermal contact while wading or swimming. Swimming in Annie Creek is unlikely because the creek is very shallow. Dermal absorption of the metals in the surface water through the skin is unlikely.
Biota
Vacationers could be exposed to metal contaminants through ingestion of game fish, particularly trout. Brown trout and brook trout were found in the lower reaches of Annie Creek and Spearfish Creek. Arsenic and selenium was detected in whole fish and fillet samples from brown and brook trout. Mountain suckers, a non-game fish, had the greatest concentration of arsenic. The seasonal residents reported that they did fish in Annie Creek.
C. Eliminated Exposure Pathways
Air
Potential exposures to air borne contaminants could have occurred when workers remediated the tailings pile. It is unlikely that workers were exposed to levels of health significance since they were enclosed in cabs of heavy machinery 30 feet above the tailings pile.
Inhalation exposure to surface contamination appears to be limited. There is a vegetative covering on contaminated areas along the creek beds and the contaminated sediments are underwater for most of the year which would limit the wind dispersion of the tailings.
Spearfish Municipal Water Supply
The Spearfish municipal water supply is obtained from a 600 foot well completed in the Madison
Formation. The municipal water supply is no longer obtained from drainages and springs below
the confluence of Annie and Spearfish Creek.
In this section, we will discuss the potential for health effects to occur based on the contaminant data collected prior to the non-time critical removal action. The levels of contaminants should be further reduced by the actions undertaken by the non-time critical removal.
Under current land-use, the individuals most likely to come in contact with the contaminants at the Annie Creek Mine Tailing Site are people visiting the vacation cabins or people who visit the area for fishing and hiking. Because of the rugged terrain, it was assumed that an older child would be the youngest and most sensitive receptor that would come in contact with the site contamination. It was assumed that seasonal residents, fisherman, or vacationers could have contact with the site contaminants for approximately 3-4 months per year.
Individuals are most likely to be exposed to site contamination through ingestion of surface water, groundwater, fish, or sediments/soils impacted by the tailings. Dermal contact was not considered a significant pathway of exposure since the metals would not be significantly absorbed through the skin. Inhalation of site contaminants is unlikely since most of the contaminated sediments or soil are either covered by vegetation or kept moist which prevents wind erosion.
Exposure to the heavily contaminated tailings at the headwaters of Annie Creek will not be discussed. The tailings have been encapsulated under 60-150 feet of waste rock.
Aluminum
Aluminum was detected in the pre-construction surface water samples at the headwaters of Annie Creek at a maximum concentration of 139 ug/L. It is unlikely that individuals would consume water from this source since the area is so remote. The quantity of aluminum ingested from periodic ingestion of the surface water does not pose a health threat to a child or adult consuming water from this source (9). Aluminum was not detected in the surface water samples obtained in 1992.
Antimony
Antimony concentrations in sediments exceeded environmental comparison values. The levels of antimony that an individual might incidentally ingest are below levels that would produce health effects.
Arsenic
Arsenic was detected in groundwater, surface water, sediments, and fish. The toxicological implications of exposure to these media are described below (10).
A. Surface Water
Surface water samples obtained from Annie Creek and Spearfish Creek contained arsenic. For a child consuming a liter of water from the surface water of Annie Creek for an intermediate period of exposure (approximately 90-120 days a year), the ATSDR Minimal Risk Level (MRL) is exceeded. The MRL is an estimate of daily exposure of a human to a chemical that is likely to be without an appreciable risk for noncarcinogenic health effects. Exceeding the MRL does not mean that a health effect is expected to occur. Based on the amount of arsenic ingested from this exposure, no adverse health effects are expected to occur.
B. Groundwater
The range of arsenic detected in the residential wells was <1-7 ug/L. The range of arsenic detected in well water does not exceed the EPA Maximum Contaminant Level (MCL) for drinking water of 50 ug/l. The MCL is the maximum permissible level of a contaminant in water that is delivered at the tap. MCLs have been deemed protective of public health based on the assumption that an individual could consume the water for a lifetime (70 years) at an exposure rate of 2 liters per day. Therefore, consumption of the water from residential wells at these reported concentrations does not pose a health threat.
C. Sediments
Arsenic concentrations in sediments exceeded environmental comparison values. The level of arsenic that an individual might incidentally ingest are below levels that would produce health effects in humans.
D. Fish
Many factors must be considered in evaluating the health implications of consumption of the fish from Annie and Spearfish Creek. One must consider the species of fish, the concentration and the bioavailability of the arsenic in the fish, and the amount of fish consumed. Two populations of fish, brown trout and mountain suckers, were harvested from Spearfish Creek in 1990. Brown trout were not found in Annie Creek. In 1992, mountain suckers, brown trout and brook trout were harvested.
Mountain suckers are a small 6-8 inch bottom feeder which are considered a non-edible species. Trout are an edible species.
Spearfish Creek is recreational fished 3-6 months a year. Fishing in Spearfish Creek is by a specified catch and release regulation i.e. only fish less than 11 inches in length can be kept for consumption. It was assumed that a recreational fisherman may have 2-4 fish meals from the trout during a one month period.
Arsenic exists in many chemical forms; inorganic arsenic is considered most toxic. Arsenic accumulates in fish in both an inorganic and organic form. The organic form of arsenic in the fish "arsenobetaine" is essentially nontoxic to the fish and the consumer. In seafood, inorganic arsenic was reported to comprise only 1% of the total arsenic in the fish (8). Based on this assumption, the amount of inorganic arsenic ingested from recreational consumption of the brown or brook trout during a 3 to 6 month period is not of health concern.
Manganese
Manganese was detected in the pre-construction surface water at the headwaters of Annie Creek. Although humans are often exposed to significant quantities of manganese compounds in food or water, reports of adverse effects in humans from ingestion of manganese are rare (12). It is unlikely that a child or adult would consume this water because of the remoteness and inaccessibility of the creek. However, if water from the creek were ingested, no adverse health effects are expected to occur.
Selenium
Selenium was detected in brook and brown trout in Spearfish Creek. Selenium is an essential nutrient. The levels that one might consume from ingestion of the fish are safe since the level ingested are less than the Recommended Dietary Allowance for selenium in the diet.
Vanadium
Vanadium was detected in the pre-construction surface water samples of Annie Creek. For children or adults consuming 1 or 2 liters of water from the surface water at the headwaters of Annie Creek, the vanadium ingested exceeds the ATSDR MRL (13). Exceeding the MRL does not necessarily mean that a health effect would be produced. Ingestion from this water source is highly unlikely due to the remoteness and the inaccessibility of the creek. If water from the creek were ingested, no adverse health effects are expected to occur.
Zinc
Zinc was detected in the pre-construction surface water samples of Annie Creek. Ingestion of the surface water from the headwaters of Annie Creek by a camper is unlikely since the area is remote. If a camper ingested 2 liters of the water at the maximum zinc concentration reported (45,500 ppb) they might experience gastrointestinal distress (vomiting and diarrhea) (14). It is most likely that the surface water zinc concentrations at the headwaters of Annie Creek have decreased since the installation of the waste rubble facility.
B. Health Outcome Data Evaluation
Chronic disease or birth defect registries are not maintained by county or state health agencies. There were no symptoms, prevalence of disease, or birth defects reported by citizens or area physicians associated with the arsenic contamination at Annie Creek.
Area physicians did report the findings of two separate medical studies which indicated an increased incidence of pneumoconiosis and respiratory tuberculosis (6) and malignant respiratory cancers (7) in gold miners in Lead, South Dakota. Miners at the Annie Creek Mines were not included in these studies since mining operations had been terminated since 1917.
C. Community Health Concerns Evaluation
Citizens expressed three primary concerns regarding the Annie Creek mine tailings to ATSDR representatives during the site visit: 1) concern about the impact of the mine tailings on the Spearfish municipal water system 2) concern about migration of contaminants from Annie Creek and Spearfish Creek into private drinking water wells located adjacent to the streams and 3) concern about bioaccumulation of heavy metals from the site in game fish in Spearfish Creek. These specific concerns will be addressed as follows:
The city no longer obtains it water supply from Spearfish Creek. The municipal water supply is obtained from a 600 foot well located in the Madison Formation. In the past, municipal water was obtained from Spearfish Creek. There were three diversions of Spearfish Creek between the confluence with Annie Creek and the City of Spearfish. There were two hydroplants for Homestake Mining Company and the City of Spearfish Municipal water intake. Between the Hydroplant #1 and the City of Spearfish Municipal water intake, Spearfish Creek is dry. The only water that reached the city water supply was from springs and drainages below Hydroplant #1. Therefore, contaminated surface water from Annie and Spearfish Creek did not reach the Spearfish municipal intake.
No, the levels of arsenic detected in the well water have not exceeded safe water quality standards. The available data (water sample from Kannonberg well, arsenic concentration (<1 ug/L) and a well sample at a residence 3/4 mile from the site along Spearfish Creek, the arsenic concentrations in the water are well below the maximum contaminant level of 50 ug/L (MCL). The MCL is a water quality standard for public water supplies. The MCL is based on the assumption that an individual consumes 2 liters of water over a lifetime.
Current fish tissue analysis does not indicate that arsenic is bioaccumulating in edible game fish at levels of health concern. Concentrations of arsenic in the trout did not exceed levels considered to be protective of human health and were comparable to levels commonly found in many food sources.
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