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Lewis and Clark County, Montana: environmental and disease records

Cancer mortality in Lewis and Clark County is 142.4 deaths per 100,000 people per year against a U.S. rate of 143.2. The strongest disease signals are Esophagus deaths at 1.9 times the U.S. rate. Federal databases place 480 regulated facilities, sites and hazards inside the county, led by NPDES wastewater discharge permit (222), Rail grade crossing (65), Auto repair or body shop (mapped facility) (51). EPA AirToxScreen estimates a lifetime cancer risk from outdoor air toxics of 20 in a million, driven mainly by formaldehyde.

Rates are age-adjusted per 100,000 people. A cancer signal is marked significant when the lower bound of its 95 percent confidence interval is above the U.S. rate. Facility counts use active federal records located inside the county boundary. Approximate county center: 47.1845, -112.5351.

How this county ranks in Montana

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Cancer deaths and new cases versus the United States

Source: NCI and CDC State Cancer Profiles, both sexes, all ages. Sorted by the ratio of the county rate to the U.S. rate.

Cancer rates for Lewis and Clark County compared with the United States
Cancer	Measure	County rate	U.S. rate	Times U.S.	95% interval	Years
Esophagus	Deaths	6.9	3.7	1.86xSignificant	4.7 to 9.8	2020-2024
Melanoma of the skin	New cases	34.8	23.8	1.46xSignificant	29.3 to 41	2019-2023
Leukemia	New cases	19.8	14.5	1.37xSignificant	15.8 to 24.5	2019-2023
Leukemia	Deaths	7.5	5.7	1.32x	5.3 to 10.5	2020-2024
Esophagus	New cases	5.9	4.6	1.28x	3.9 to 8.6	2019-2023
Bladder	New cases	23.5	18.7	1.26xSignificant	19.3 to 28.4	2019-2023
Brain & nervous system	Deaths	5.4	4.4	1.23x	3.4 to 8.1	2020-2024
Brain & nervous system	New cases	7.3	6.2	1.18x	4.9 to 10.5	2019-2023
Pancreas	Deaths	12.4	11.3	1.1x	9.5 to 15.9	2020-2024
Pancreas	New cases	14.8	13.9	1.06x	11.6 to 18.8	2019-2023
All cancer	New cases	477.5	453.4	1.05xSignificant	457.4 to 498.3	2019-2023
Bladder	Deaths	4.2	4.1	1.02x	2.5 to 6.6	2020-2024
Stomach	New cases	6.7	6.6	1.02x	4.6 to 9.6	2019-2023
Thyroid	New cases	13	13	1x	9.5 to 17.3	2019-2023
All cancer	Deaths	142.4	143.2	0.99x	131.9 to 153.7	2020-2024
Non-Hodgkin lymphoma	New cases	17.6	18.5	0.95x	14 to 22.1	2019-2023
Kidney & renal pelvis	New cases	16.9	17.9	0.94x	13.2 to 21.3	2019-2023
Non-Hodgkin lymphoma	Deaths	4.4	4.8	0.92x	2.7 to 6.8	2020-2024
Lung & bronchus	New cases	47	51.8	0.91x	41.1 to 53.5	2019-2023
Lung & bronchus	Deaths	27	30.2	0.89x	22.7 to 32	2020-2024
Liver & bile duct	Deaths	5.8	6.6	0.88x	4 to 8.4	2020-2024
Liver & bile duct	New cases	7.1	8.7	0.82x	5.1 to 9.9	2019-2023

Mortality measures versus the U.S. county median

Source: County Health Rankings, built from CDC National Vital Statistics System death records. The comparison value is the median of all U.S. counties.

Mortality measures for Lewis and Clark County
Measure	County	U.S. median	Difference	Unit
Premature death	6,948.1	9,842.6	-29%	years of life lost before age 75 per 100,000
Life expectancy	78.3	75.3	+4%	years
Child mortality	52.1	59.8	-13%	deaths under age 18 per 100,000
Infant mortality	n/a	6.2	n/a	deaths under age 1 per 1,000 live births
Injury deaths	82.7	96.9	-15%	deaths per 100,000
Drug overdose deaths	13.9	28.6	-52%	deaths per 100,000

Air toxics and air quality

EPA AirToxScreen 2020

Lifetime cancer risk from outdoor air toxics: 20 in a million. EPA treats 100 in a million as the upper end of acceptable risk and 1 in a million as the goal.

Formaldehyde10.66 per million
Carbon Tetrachloride2.63 per million
Acetaldehyde1.36 per million
Naphthalene1.28 per million

EPA Air Quality Index 2025

Monitored on 365 days: 261 good, 0 unhealthy for sensitive groups or worse. Median AQI 44, peak 93.

Regulated facilities, sites and hazards by type

480 active records inside the county from EPA ECHO, TRI, Superfund, Brownfields, NPDES, EIA, FAA, FRA and corrections data.

NPDES wastewater discharge permit222
Rail grade crossing65
Auto repair or body shop (mapped facility)51
Gas station (mapped facility)34
Brownfield property30
Public airport14
Air permit holder (minor source)12
Small hazardous waste generator10
Scrapyard (mapped facility)8
Toxic chemical release facility (TRI)5
EPA air quality monitor3
Crematorium (mapped facility)3
Dry cleaner (mapped facility)3
Heliport3
Hydroelectric plant3
Wastewater plant (mapped facility)3
Solar power plant2
Superfund (NPL) site2
TRI reporting facility2
Major air pollution source1
Commercial airport1
Large greenhouse gas emitter1
Large hazardous waste generator1
Landfill (mapped facility)1

Highest-severity records

The 25 records with the highest Envyrofax severity in the county, with the agency identifier to cite in a records request.

East Helena Site, East Helena
Superfund (NPL) site. Hazard Ranking System score 61.7. NPL Site.
EPA site ID MTD006230346 (U.S. EPA Superfund (SEMS/NPL)) Agency record
Severity 10
Upper Tenmile Creek Mining Area, Helena, Rimini
Superfund (NPL) site. Hazard Ranking System score 50. NPL Site.
EPA site ID MTSFN7578012 (U.S. EPA Superfund (SEMS/NPL)) Agency record
Severity 10
American Chemet Corp, East Helena
Toxic chemical release facility (TRI). Chemicals: Ammonia, Copper And Copper Compounds, Lead. Reports carcinogens. 96,155 lbs released over 5 years.
TRI facility ID 59635MRCNCSMELT (U.S. EPA Toxics Release Inventory)
Severity 8.3
Us Army National Guard Fort Harrison Ranges, Fort Harrison
Toxic chemical release facility (TRI). Chemicals: Lead. Reports carcinogens. 31,037 lbs released over 5 years.
TRI facility ID 5963WFTHRRNGMTE (U.S. EPA Toxics Release Inventory)
Severity 7.9
American Chemet, East Helena
TRI reporting facility.
EPA FRS registry ID 110058937977 (U.S. EPA ECHO) Agency record
Severity 5.9
U.S. Army National Guard Fort Harrison Ranges, Fort Harrison
TRI reporting facility.
EPA FRS registry ID 110039204535 (U.S. EPA ECHO) Agency record
Severity 5.7
Ups - Helena, Helena
NPDES wastewater discharge permit. Penalties $5,300,000.
EPA FRS registry ID 110004009028 (U.S. EPA ECHO) Agency record
Severity 5.5
City Of Helena Wwtp, Helena
NPDES wastewater discharge permit. Penalties $20,000.
EPA FRS registry ID 110013403094 (U.S. EPA ECHO) Agency record
Severity 5
Helena Rgnl, Helena
Commercial airport. O.
Record ID HLN (FAA / U.S. DOT)
Severity 5
ROSSITER PUMP HOUSE, Helena Valley West Central
EPA air quality monitor.
Record ID 300490026 (U.S. EPA AirData)
Severity 4.8
Forterra Concrete Products - Helena, Helena
Toxic chemical release facility (TRI). Chemicals: Lead. Reports carcinogens.
TRI facility ID 5960WFRTRR21NBE (U.S. EPA Toxics Release Inventory)
Severity 4.5
Gates Of The Mountains Inc, Helena
NPDES wastewater discharge permit.
EPA FRS registry ID 110011048339 (U.S. EPA ECHO) Agency record
Severity 4.5
Helena Regional Airport, Helena
NPDES wastewater discharge permit.
EPA FRS registry ID 110011048678 (U.S. EPA ECHO) Agency record
Severity 4.5
Grand Valley Estates, Helena
NPDES wastewater discharge permit.
EPA FRS registry ID 110023137336 (U.S. EPA ECHO) Agency record
Severity 4.5
Bridge Creek Estates, Helena
NPDES wastewater discharge permit.
EPA FRS registry ID 110024408568 (U.S. EPA ECHO) Agency record
Severity 4.5
Glacier Point Subdivision, Helena
NPDES wastewater discharge permit.
EPA FRS registry ID 110028114948 (U.S. EPA ECHO) Agency record
Severity 4.5
Applegate Meadows Subdivision, Helena
NPDES wastewater discharge permit.
EPA FRS registry ID 110044904994 (U.S. EPA ECHO) Agency record
Severity 4.5
Bryant No 3 Subdivision Community Wastewater Facility, Helena
NPDES wastewater discharge permit.
EPA FRS registry ID 110045343080 (U.S. EPA ECHO) Agency record
Severity 4.5
Cretext Concrete Products West, Helena
NPDES wastewater discharge permit.
EPA FRS registry ID 110058943425 (U.S. EPA ECHO) Agency record
Severity 4.5
Hayfield Estates Ii Lot 25 Jamor Subdivision Wastewater Treatment System, Helena
NPDES wastewater discharge permit.
EPA FRS registry ID 110064605903 (U.S. EPA ECHO) Agency record
Severity 4.5
Wastewater Treatment Facility, Helena
NPDES wastewater discharge permit.
EPA FRS registry ID 110070505652 (U.S. EPA ECHO) Agency record
Severity 4.5
Smith Subdivisions Public Wastewater Treatment System, East Helena
NPDES wastewater discharge permit.
EPA FRS registry ID 110070941155 (U.S. EPA ECHO) Agency record
Severity 4.5
Boeing Helena Inc, Helena
Toxic chemical release facility (TRI). Chemicals: Nickel, Chromium. Reports carcinogens.
TRI facility ID 5960WBNGHL32SKY (U.S. EPA Toxics Release Inventory)
Severity 4.5
Bmc West Truss Plant, Helena
NPDES wastewater discharge permit.
EPA FRS registry ID 110010121215 (U.S. EPA ECHO) Agency record
Severity 4.3
Helena Rail Yard, Helena
NPDES wastewater discharge permit.
EPA FRS registry ID 110010826053 (U.S. EPA ECHO) Agency record
Severity 4.3

Correctional facilities

Prisons, jails and corrections operations with an EPA facility record, and the drinking water and wastewater compliance attached to them.

No correctional facility with an EPA record is located in this county.

Discovery / public records

Records to request for Lewis and Clark County

Montana state cancer registry
Cancer incidence counts by census tract or ZIP code, by cancer type and year (de-identified). Any cancer cluster inquiries or investigations in Lewis and Clark County, and their findings.
Montana vital statistics office
Death certificate counts by cause of death and residence tract or ZIP code, and the years behind the mortality measures above.
Montana health department, environmental epidemiology
Health consultations or assessments by ATSDR or the state health department covering the county, and any exposure investigations.
Montana environmental agency and the U.S. EPA regional office
Compliance history, inspection reports, notices of violation, penalties and enforcement actions for each facility above, cited by EPA FRS registry ID.
Montana drinking water program
Violation notices, sampling results and sanitary surveys for the public water systems serving the county, including any system serving a correctional facility.
Department of corrections or county sheriff
Water testing, grievances and environmental health inspections for the correctional facilities listed above.

Each Envyrofax address report includes a printable records request worksheet with the custodian and the exact request wording per finding.

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