Markwest Hidalgo Plant – Emissions Trend
Orla, TX · 2022–2023 · Parent: Marathon Petroleum Corp
This page assembles 2 consecutive years of EPA Toxics Release Inventory Form R filings for Markwest Hidalgo Plant, spanning 2022–2023. 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 147.1K in 2022 and closed at 72.6K in 2023 – a decrease of 50.6% 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 Ethylene glycol at 67.1K, followed by Naphthalene at 63.9K.
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 natural gas processing facility.
Total Releases by Category
Year-over-Year Comparison
| Year | Total | Chemicals | YoY Change |
|---|---|---|---|
| 2022 | 147.1K lbs | 10 | - |
| 2023 | 72.6K lbs | 4 | -50.6% |
Top Chemicals by Year
| Chemical | 2022 | 2023 | Total |
|---|---|---|---|
| Ethylene glycol | - | 67.1K | 67.1K |
| Naphthalene | 63.9K | - | 63.9K |
| Xylene (mixed isomers) | 32.0K | - | 32.0K |
| Toluene | 16.0K | - | 16.0K |
| 1,2,4-Trimethylbenzene | 16.0K | - | 16.0K |
| n-Hexane | 8.0K | 5.6K | 13.6K |
| Benzene | 8.0K | - | 8.0K |
| Ethylbenzene | 1.6K | - | 1.6K |
| Cumene | 1.6K | - | 1.6K |
| Cyclohexane | - | - | 0 |
| Methanol | - | - | 0 |
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 Markwest Hidalgo Plant getting cleaner or dirtier? ▼
What time period does this trend data cover? ▼
Read our methodology - how this data is sourced, computed, and verified.