Hardin Generating Station – Emissions Trend
Hardin, MT · 2019–2023 · Parent: Rocky Mountain Power LLC
This page assembles 5 consecutive years of EPA Toxics Release Inventory Form R filings for Hardin Generating Station, spanning 2019–2023. Each annual total aggregates on-site air emissions, surface-water discharges, land disposal, and off-site transfers reported by the facility under EPCRA Section 313, which requires disclosure whenever a listed chemical is manufactured, processed, or otherwise used above threshold quantities.
Reported releases opened at 31.4K in 2019 and closed at 114.5K in 2023 – a increase of 265.0% over the window. The chart below stacks the four TRI release media (air, water, land, off-site) and overlays the yearly total. The top contributor by cumulative mass is Barium And Barium Compounds at 282.5K, followed by Manganese at 111.5K.
Because TRI figures are estimated, not metered, year-over-year deltas can reflect methodology revisions, ownership changes, or shifts in what a facility classifies as reportable, not only physical emission changes. Treat the trajectory as a disclosure record, and cross-reference with the EPA Enforcement and Compliance History Online (ECHO) system for the fuller regulatory picture on this electric utilities facility.
Total Releases by Category
Year-over-Year Comparison
| Year | Total | Chemicals | YoY Change |
|---|---|---|---|
| 2019 | 31.4K lbs | 10 | - |
| 2020 | 9.0K lbs | 6 | -71.3% |
| 2021 | 198.3K lbs | 10 | +2104.6% |
| 2022 | 176.8K lbs | 10 | -10.8% |
| 2023 | 114.5K lbs | 10 | -35.3% |
Top Chemicals by Year
| Chemical | 2019 | 2020 | 2021 | 2022 | 2023 | Total |
|---|---|---|---|---|---|---|
| Barium And Barium Compounds | - | 8.5K | 115.0K | 98.6K | 60.3K | 282.5K |
| Manganese | - | - | 46.8K | 40.1K | 24.6K | 111.5K |
| Sulfuric acid (acid aerosols including mists, vapors, gas, fog, and other airborne forms of any particle size) | 7.6K | - | 27.0K | 29.9K | 24.3K | 88.8K |
| Barium compounds (except for barium sulfate (CAS No. 7727-43-7)) | 14.3K | - | - | - | - | 14.3K |
| Zinc compounds | 675 | 235 | 3.3K | 2.8K | 1.7K | 8.7K |
| Copper | - | - | 3.5K | 3.0K | 1.8K | 8.2K |
| Manganese compounds | 7.4K | - | - | - | - | 7.4K |
| Lead And Lead Compounds | - | 159 | 2.0K | 1.8K | 1.1K | 5.1K |
| Hydrochloric acid (acid aerosols including mists, vapors, gas, fog, and other airborne forms of any particle size) | 91 | 33 | 322 | 355 | 289 | 1.1K |
| Hydrogen fluoride | 91 | - | 322 | 355 | 289 | 1.1K |
| Copper compounds | 722 | - | - | - | - | 722 |
| Lead compounds | 437 | - | - | - | - | 437 |
| Arsenic And Arsenic Compounds | - | 50 | - | - | - | 50 |
| Mercury And Mercury Compounds | - | 1 | 13 | 14 | 9 | 38 |
| Mercury compounds | 5 | - | - | - | - | 5 |
About This Data
Trend data is sourced from the EPA Toxic Release Inventory (TRI). Facilities report annually. Release quantities are self-reported estimates. Year-over-year changes may reflect changes in production, pollution control measures, reporting methodology, or chemical thresholds.
A decrease in reported releases does not necessarily indicate improved environmental performance, as it may reflect production cutbacks, facility closures, or changes in reporting requirements. Similarly, increases may reflect expanded production rather than degraded environmental practices.
Frequently Asked Questions
Is Hardin Generating Station getting cleaner or dirtier? ▼
What time period does this trend data cover? ▼
Read our methodology - how this data is sourced, computed, and verified.