# Relationship history for MSHA mine 3304431

Current hierarchy: **Bill D  Colwell → Colwell Gravel Company → COLWELL GRAVEL CO.**

- 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:** Colwell Gravel Company → COLWELL GRAVEL CO.; 1998-11-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Bill D  Colwell → COLWELL GRAVEL CO.; 1998-11-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Bill D  Colwell → Colwell Gravel Company; 1998-11-01 to current/open; source msha-controller-operator-history