# Relationship history for MSHA mine 2901153

Current hierarchy: **Westmoreland Mining Holdings LLC → San Juan Coal Company → San Juan Preparation Plant**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **operator_operates_mine:** Western Coal Company → San Juan Preparation Plant; 1973-11-01 to 1981-01-08; source msha-controller-operator-history
- **controller_controls_mine:** Public Service Co of New Mexico et al → San Juan Preparation Plant; 1973-11-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Public Service Co of New Mexico et al → Western Coal Company; 1973-11-01 to 1981-01-08; source msha-controller-operator-history
- **controller_controls_operator:** Tucson Gas & Electric Co  et al → Western Coal Company; 1973-11-01 to 1981-01-08; source msha-controller-operator-history
- **controller_controls_mine:** General Electric Company → San Juan Preparation Plant; 1974-01-01 to 1984-04-01; source msha-controller-operator-history
- **operator_operates_mine:** San Juan Coal Company → San Juan Preparation Plant; 1981-01-09 to 1984-04-01; source msha-controller-operator-history
- **controller_controls_operator:** General Electric Company → San Juan Coal Company; 1981-01-09 to 1984-04-01; source msha-controller-operator-history
- **operator_operates_mine:** San Juan Coal Company → San Juan Preparation Plant; 1984-04-02 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** BHP Billiton → San Juan Preparation Plant; 1984-04-02 to 2016-01-31; source msha-controller-operator-history
- **controller_controls_operator:** BHP Billiton → San Juan Coal Company; 1984-04-02 to 2016-01-31; source msha-controller-operator-history
- **controller_controls_mine:** Westmoreland Coal Company → San Juan Preparation Plant; 2016-02-01 to 2019-03-14; source msha-controller-operator-history
- **controller_controls_operator:** Westmoreland Coal Company → San Juan Coal Company; 2016-02-01 to 2019-03-14; source msha-controller-operator-history
- **controller_controls_mine:** Westmoreland Mining Holdings LLC → San Juan Preparation Plant; 2019-03-15 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Westmoreland Mining Holdings LLC → San Juan Coal Company; 2019-03-15 to current/open; source msha-controller-operator-history