# Relationship history for MSHA mine 4503286

Current hierarchy: **Northwest Carbonates; Bleeck Management → Columbia River Carbonates → Columbia River Carbonates (Woodland Mill**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-18T09:31:49.615908+00:00

## Valid-time edges

- **controller_controls_mine:** Northwest Carbonates  et al → Columbia River Carbonates (Woodland Mill; 1986-09-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Columbia River Carbonates → Columbia River Carbonates (Woodland Mill; 1993-03-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Northwest Carbonates  et al → Columbia River Carbonates; 1993-03-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Bleeck Management  et al → Columbia River Carbonates; 1993-03-01 to current/open; source msha-controller-operator-history