# Relationship history for MSHA mine 5001798

Current hierarchy: **William E  Toelkes → International Bridge Corporation → Koyukuk Gravel Quarry**

- 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

- **operator_operates_mine:** International Bridge Corporation → Koyukuk Gravel Quarry; 2004-07-08 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** William E  Toelkes → Koyukuk Gravel Quarry; 2004-07-08 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** William E  Toelkes → International Bridge Corporation; 2004-07-08 to current/open; source msha-controller-operator-history